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EEE 314. Lecture 1.
Prepared by: Md. Itrat Bin Shams
Mr. Yeasir Arafat Contents
1. Drafting 2
2. Ratings of Electrical appliances 2
3. Description of Protecting Devices: 3
3.1 Relays . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . 3 3.2 Fuse . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . 3 3.3 Circuit Breakers . . . . . . . . . .
. . . . . . . . . . . . . . . . . 4
4. Grounding and Hazards 5
5. Illumination and lightning 6
5.1 Some definitions . . . . . . . . . . . . . . . . . . . . . .
. . . . . 6 5.2 Law of illumination . . . . . . . . . . . . . . . .
. . . . . . . . . . 7 5.3 Lamberts cosine law . . . . . . . . . . .
. . . . . . . . . . . . . . 7 5.4 Design of lighting scheme . . . .
. . . . . . . . . . . . . . . . . . 8 5.5 Lighting Schemes . . . .
. . . . . . . . . . . . . . . . . . . . . . . 8 5.6 Outdoor
lighting for general illumination . . . . . . . . . . . . . . 8 5.7
Method of lighting calculation . . . . . . . . . . . . . . . . . .
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1. Drafting
A reasonable amount of mathematical ability. Patience. An
orderly mind. Imagination and ability to visualize. Ability to
concentrate. Neatness.
2. Ratings of Electrical appliances
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3. Description of Protecting Devices
Main features of protecting devices: Sensitivity Selectivity
Reliability Quickness: Non-interference with future expansion
3.1 Relays
Types of relays: (i) According to construction and principle of
operation: Attracted Armature Type Solenoid Type Electro dynamic
Type Induction type Thermal Type Moving coil type (ii) According to
application: Over Voltage/ Over Current /Over Power Relay Under
voltage/ Under Current /Under Power Relay Directional or Reverse
Power Relay Directional or Reverse Current Relay Differential Relay
Distance Relay (iii) According to Timing Characteristics:
Instantaneous Relay Definite Time Lag Relay Inverse Time Lag
Relay
3.2 Fuse
A fuse must fulfill following criteria: During normal operating
conditions fuses must not have any effect over circuits. A fuse
must sense a short circuit or overload. A fuse must open the
circuit before any harm is caused to the system.
Figure 1
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Fuses can be classified as,
Edison Base Fuses Type S Fuses Cartridge-Type Fuses Ferrule-Type
Fuses Knife Blade-Type Fuses
Figure 2
Figure 3
3.3 Circuit Breakers
Classification of Circuit Breakers: Electromagnetic-Type Circuit
Breaker Thermal-Type circuit breaker
Figure 4
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Figure 5
4. Grounding and Hazards
a. Grounding by the electric utility b. Grounding by the
electrician
1. Fire Hazard 2. Shock Hazard Two basic rules must be followed
when working near an electrical circuit.
They are, 1. Always turn off power before working on a circuit.
2. Confirm that the circuit is de-energized by checking that it is
off using a voltage tester. There are several ways to make sure
that a circuit is in de-energized state.
A good practice to see whether a circuit is in off state or not
is to connect a lamp across it and see if it lits up or not. If the
circuit is equipped with fuses then removing a particular fuse will
make sure that specific portion of a circuit is removed from the
system. If circuit breaker is used, switching it off will do the
same job. Another way to make sure that circuit is absolutely dead
is as follows.
A portion of the circuit is connected to ground. So a huge
current flow through the conductor making nearby fuse to be melt
down. As a result circuit is isolated.
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5. Illumination and lightning
Radiant efficiency =body by the radiatedenergy Total
light of form in the radiatedEnergy
Figure 6 5.1 Some definitions
Light: It may be defined as that radiant energy which produces a
sensation of vision upon the human eye. Luminous flux: It is
defined as the light energy radiated per second from a luminous
body.
Figure 7
Luminous intensity: If dF is the luminous flux crossing any
section of narrow cone of solid angle d steradian then, luminous
intensity is,
ddFI
Lumen: It is the unit of flux and is defined as the luminous
flux per unit solid angle from a source of 1 candle power.
Illuminance or illumination or degree of illumination:
Illumination can be defined as the luminous flux received per unit
area.
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Illumination = dAdF
Brightness: In the figure let the luminous intensity in the
direction OP be 1 lumen per steradian on an area A, the projected
area will then be Acos .
Brightness B=cos
1A
Figure 8
5.2 Law of illumination
The illumination of a surface is inversely proportional to the
square of the distance of the surface from the source of light. It
is true only if the source is a point source.
5.3 Lamberts cosine law
According to this law the illumination of surface at any point
is dependent upon the cosine of the angle between the line of flux
and the normal at that point.
In the figure,
Intensity of illumination =ABCD AreaF
= cosabcd Area
F
Figure 9
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5.4 Design of lighting scheme Space-height ratio: It can be
defined as, The horizontal distance between lamps/Mounting height
of lamps This ration stays within the range of 1 to 2. Utilization
factor: It is, Total lumens utilized on working planes/Total lumens
radiated by lamp. The value of this co-efficient depends on the
following factors: The area to be illuminated. Height of the lamps.
The color of the surrounding walls. Type of lighting- direct or
indirect. Depreciation factor: It is, Illumination under normal
working conditions/Illumination when everything is clean. Its value
is normally 0.8. Its reverse definition is also true.
5.5 Lighting Schemes Direct lighting Indirect lighting
Semi-direct lighting Semi-indirect lighting Type R and PAR type
bulbs
5.6 Outdoor lighting for general illumination Outdoor lighting
is necessary for security purposes. Two types will be discussed
here. Motion detector control Automatic timer control
Figure 10
Motion Detector Control: Motion sensors automatically turn
outdoor lights on when motion is detected and turn off a short
while after. They are very useful for outdoor security and utility
lighting. These lights are needed only when it is dark and people
are present, the best way to control might be a combination of
motion sensor and photosensor. Incandescent flood lights with a
photosensor and motion sensor may actually use less energy than
pole-mounted high intensity discharge or low pressure sodium
security lights
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controlled by a photosensor. Automatic Timer Control: Timers can
be used to turn on and off outdoor lights at specific times. Simple
timers are not often used alone for outdoor lighting because the
timer may have to be reset often with seasonal variation in the
length of night. However, they can be used effectively in
combinations with other controls.
Figure 11 5.7 Method of lighting calculation
Watts per square meter method
Lumens or light flux method
ofeachlampefficiencyampswattageofloflampsnoonfactordepreciati
tiontofutilizacoefficien .
or Confinement of utilizationmaintenance factorno. of
lampswattage of lamps
efficiency of each lamp
Point to point or inverse square law method
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Figure 12
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Revised by Shama Naz Islam, Lecturer, EEE, BUET
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EEE 314 Lecture 2 Prepared by: Md. Itrat Bin Shams (Sanin)
Contents 1 Basic electrical appliances 2 1.1 Incandescent light
bulb . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2
Fluorescent lamp . . . . . . . . . . . . . . . . . . . . . . . . .
2 1.3 Refrigerator . . . . . . . . . . . . . . . . . . . . . . . .
. . . . 3 1.4 Iron . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . 3 1.5 Oven . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . 3 1.6 Microwave Oven . . . . . . . . . . .
. . . . . . . . . . . . . . . 3 2 Fittings and Fixtures 3 2.1
Consumer unit . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Distribution Board . . . . . . . . . . . . . . . . . . . . . .
. . 3 2.3 Service Entrance Panel Design . . . . . . . . . . . . . .
. . . . 4 2.4 Types of Branch Circuits . . . . . . . . . . . . . .
. . . . . . . 4 2.5 Conduits and Boxes . . . . . . . . . . . . . .
. . . . . . . . . . 5 2.6 Electrical Boxes . . . . . . . . . . . .
. . . . . . . . . . . . . . 5 2.6.1 General purpose metal boxes . .
. . . . . . . . . . . . . 6 2.7 Installing boxes and cables . . . .
. . . . . . . . . . . . . . . . 7 2.7.1 Consideration before
wiring, Design factors . . . . . . . 7 2.7.2 Requirement for
installing boxes and cables . . . . . . 7 2.7.3 Installing type NM
cable in metal boxes . . . . . . . . 8 2.7.4 Making wire connection
. . . . . . . . . . . . . . . . . 9 2.7.5 Splicing wire . . . . . .
. . . . . . . . . . . . . . . . . . 9 2.7.6 Rain tight boxes and
covers . . . . . . . . . . . . . . . 9 2.7.7 Watertight boxes and
box extensions . . . . . . . . . . 10 2.8 Switches . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . 11 2.8.1 Special types
of switches . . . . . . . . . . . . . . . . . 11 2.8.2 The pull
chain switches . . . . . . . . . . . . . . . . . . 11 2.8.3 Single
pole switch loop . . . . . . . . . . . . . . . . . . 12 2.8.4 three
way switch . . . . . . . . . . . . . . . . . . . . . 12 2.8.5 Four
way switch . . . . . . . . . . . . . . . . . . . . . . 13 2.9
Lighting fixtures . . . . . . . . . . . . . . . . . . . . . . . . .
13 3 Earthing 14 3.1 Some definitions . . . . . . . . . . . . . . .
. . . . . . . . . . . 14 3.1.1 Earth electrode . . . . . . . . . .
. . . . . . . . . . . . 14 3.1.2 Earthing lead or main earthing
conductor . . . . . . . 15 3.1.3 Sub-main earthing conductor . . .
. . . . . . . . . . . 15 3.1.4 Earthing continuity conductor . . .
. . . . . . . . . . . 15 3.2 Factors on which earth resistance
depends . . . . . . . . . . . 15 3.3 Methods of earthing . . . . .
. . . . . . . . . . . . . . . . . . 15 3.3.1 Earthging through a
water main . . . . . . . . . . . . . 15 3.3.2 Pipe earthing . . . .
. . . . . . . . . . . . . . . . . . . 15 3.3.3 Plate earthing . . .
. . . . . . . . . . . . . . . . . . . . 15
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1 Basic electrical appliances
1.1 Incandescent light bulb The incandescent light bulb or
incandescent lamp is a source of artificial light that works by
incandescence. An electrical current passes through a thin
filament, heating it and causing it to become excited, releasing
thermally equilibrated photons in the process. The enclosing glass
bulb prevents the oxygen in air from reaching the hot filament,
which would be otherwise rapidly destroyed by oxidation. A benefit
of the incandescent bulb is that they can be produced for a wide
range of voltages, from a few volts to several hundred volts.
Because of their relatively poor luminous efficacy, incandescent
light bulbs are gradually being replaced in many applications by
fluorescent lights, high-intensity discharge lamps, LEDs, and other
devices. 1.2 Fluorescent lamp A fluorescent lamp is a gas-discharge
lamp that uses electricity to excite mercury vapor in argon or neon
gas, resulting in a plasma that produces short-wave ultraviolet
light. This light then causes a phosphor to fluoresce, producing
visible light. Unlike incandescent lamps, fluorescent lamps always
require a ballast to regulate the flow of power through the
lamp.
Figure 1
Figure 2
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1.3 Refrigerator A refrigerator (often called a fridge for
short) is a cooling appliance for the storage and preservation of
perishable food; food kept in a refrigerator lasts longer than that
left at room temperature as the cold inhibits bacterial growth. 1.4
Iron Ironing works by loosening the bonds between the long-chain
polymer molecules in the fibres of the material. While the
molecules are hot, the fibres are straightened by the weight of the
iron, and they hold their new shape as they cool. 1.5 Oven An oven
is an enclosed compartment for heating, baking or drying. It is
most commonly used in cooking and pottery. Two common kinds of
modern ovens are gas ovens and electric ovens. Ovens used in
pottery are also known as kilns. An oven used for heating or for
industrial processes is called furnace.
1.6 Microwave Oven A microwave oven, or microwave, is a kitchen
appliance employing microwave radiation primarily to cook or heat
food.
2 Fittings and Fixtures To accommodate a house with electrical
appliances, it is necessary to provide adequate fittings and
fixture installations. 2.1 Consumer unit A consumer unit is a
combination of single row fuses and breakers. If only fuses exist ,
then it is called fuse box. 2.2 Distribution Board Distribution
board is a collection of fuses and breakers. They are placed in a
double array. Distribution board is responsible for all the power
supply at home.
Figure 4
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2.3 Service Entrance Panel Design Most service entrance panels
are provided with main disconnect circuit breaker. It prevents the
home from accidents and ensures overcurrent protection. Normally
main circuit breaker is connected to two parallel bus bars. Branch
circuit breakers are then connected to each of them to feed each of
the branch circuits. Branch circuits can also be connected remotely
from the service entrance. Branch circuits are responsible to loads
to energy sources. They provide wiring between final protecting
device and the outlet of a circuit. Each branch circuit has three
wires. One is main energy carrier, second one is neutral wire and
final one is ground wire. If we need more than rated voltage two
branch circuits are to be considered simultaneously. 2.4 Types of
Branch Circuits There are mainly two types of branch circuits
available. 1. Single outlet branch circuit: Following outlets are
connected to a single outlet branch circuit. a. Dishwasher b. Range
c. Clothes dryer d. Garbage disposal e. Water heater f. Each
appliances rated more than 1000W g. Each permanently connected
motor rated half horse power or more. 2. Two or more outlet branch
circuits: Different wires are used for different branch circuits,
such as,
Circuit Rating in AMPs
Copper Wire Size
15 14 20 12 30 10 40 8 50 6
15 amps branch circuit is normally used for ordinary lighting
instruments. 20 amps circuits are used for refrigeration purpose,
pantry, breakfast room, dining room etc. When 20 amps circuits are
provided both 15 and 20 amps receptacles are to be provided. A 15
amps circuit can be fed into a 20 amps receptacle but reverse
cannot be done. 30 or 40 amps branch circuits are used for clothes
dryer and other high current equipments in dwelling places.
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2.5 Conduits and Boxes
Types of conduits used: Rigid steel: This type of metal conduit
is supplied in 10 foot lengths of steel or aluminium. It can be of
6 inches of diameter. Its inner surface is smooth. If this conduit
has any chance to come in contact with the earth then a protective
coating is necessary. For cinder filled environment plastic coating
can be given. Inter mediate metallic (IMC): Diameter of IMC can be
up to 4 inches and it has thinner wall than rigid type. Electrical
metallic tubing (EMT): Electrical metallic tubing is similar to
Rigid type but it is thinner and its diameter can be up to 4
inches. It is not threaded and has its own type of connectors.
Flexible steel conduit: It is flexible in nature and can be given
any shape. When used a separate grounding wire must be provided as
it has much higher resistance.
Rigid non-metallic conduit and Electrical non-metallic tubing
(ENT): Non metallic conduits are made of Polyvinyl Chloride (PVC),
fiberglass, polyethylene, transite and others. There are two basic
types: rigid metal type and electrical non-metallic tubing. It can
be bent and given any shape via hot air, hot liquid or hot box. No
flames should be used. When two parts are needed to be joined a
solvent-type cement.
2.6 Electrical Boxes
Electrical boxes can best described as the termination
enclosures that accommodate the entrance of the various types of
conduits, armored cables or non-metallic sheathed cables for the
purposes of splicing the wires and providing circuit outlets for
switches, receptacles, fixtures and other electrical accessories.
Selection of boxes are dependent on the following things: The
number of wires entering The kind and number of devices attached to
it The wiring method used
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2.6.1 General purpose metal boxes General purpose boxes are of
three types: Switch boxes: Switch boxes are gangable. This means
two or three boxes can be connected together. Octagon Boxes: These
types of boxes are used for special purposes. Square boxes: Steel
square boxes are versatile in nature as they can be used for both
concealed wiring work or exposed wiring installations. Ceiling pan
boxes: These are used in roof tops.
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2.7 Installing boxes and cables
2.7.1 Consideration before wiring, Design factors An electric
service with adequate capacity Wires of sufficient capacity
throughout A sufficient number of circuits A sufficient number of
plug in receptacles An adequate number of lights Wall switches in
sufficient number Provision for security for both inside and
outside 2.7.2 Requirement for installing boxes and cables In walls:
Base receptacle boxes are normally placed 12 or 16 inches high
above the ground. Wall switch boxes are normally located 44-48
inches above the floor on the latch side of each door. In ceiling:
Proper placement must be made so that no harm is done on the
roof.
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Under floors: Similar remedies are taken.
2.7.3 Installing type NM cable in metal boxes Wires must be
placed so that proper connection is possible.
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2.7.4 Making wire connection Striping NM cable sheaths: For this
a stripper is used. NM cable is penetrated to the stripper, and it
is squeezed and moved to cut adequate amount of insulation. A knife
is used to remove the sheath. Stripping armored cable sheaths: A
fine tool hacksaw is the best for this job. Stripping wire
insulation: To strip wire insulation one must not cut the sheath at
right angles, he should use 60 degree angle. This prevents
unnecessary wire cutting.
2.7.5 Splicing wire Proper splicing is necessary to avoid
accidents in case of heavy loads. Wirenut Connectors: This is the
most basic type of connection between two wires. Electrical tape
can be wrapped around the base of the wirenut and the wires. Crimp
Connectors: Crimp connectors are used when cables entering metal
boxes require the splicing individual bare grounding wires
together. Here wires are twisted together first and then a ring is
used to make the contact. Ring is squeezed to make connection.
Connectors for Larger wire sizes: For this clamp or split bolt type
connectors are used. 2.7.6 Rain tight boxes and covers They are
usually made of painted sheet metal and have a guard to protect
against the entry of rain falling on top of the box. Some feature
like self-closing is also available.
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2.7.7 Watertight boxes and box extensions These are built to
protect switches from temporary immersion or sprinkling. Box
extensions are available for this sort of fittings. They eliminate
costly and time consuming breaking and repairing of walls.
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2.8 Switches 2.8.1 Special types of switches Mercury switches:
Uses mercury for a contact so the switch must be installed right
side up and vertical for smooth operation. Dimmer switches: They
are used to control the intensity of light and conserve energy.
Time delay switch: To make a light automatically turned off after
someone left that place. Pilot light witch: Useful for controlling
outdoor or remote lights. Lighted handle switch: Helps to find a
switch in the dark. Manual timer switch: Has a spring wound timer
that can be used up to 12 hours. Clock switch: Has a digital read
out of the time built into switch. Locking switch: Can be wired
into circuits supplying outlets. 2.8.2 The pull chain switches This
is one of the least expensive ways to build a switch.
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2.8.3 Single pole switch loop When this type of switches are
used two wires are necessary. Black wire connects with the power
line and white wire with the shell of the lighting fixture. A
switch must be installed in a hot wire and not in a neutral wire.
It makes the device connected to the switch to be in ground
potential. This prevents any shock from the device. 2.8.4 Three way
switch This type of switch is used for a hall light that can be
controlled from the bottom and top of a staircase or an outside
light be controlled from inside and outside of a house. A three way
switch is a single pole double throw switch. Three way switch means
it has three terminals and not three switches.
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2.8.5 Four way switch It is used to control a light from three
different points. Here a three way switch is installed near the
load and another distant from the load. The four way switches can
be installed between the three way switches.
2.9 Lighting fixtures There various types of lighting fixtures.
Some are, Emergency light Flood light Safelight Safety lamp
Searchlight
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Security lighting Street light Spotlight Torch lamp or torchiere
Landscape or outdoor lighting Night light
Figure 22: Four way switch
3. Earthing
3.1 Some definitions 3.1.1 Earth electrode The conductor
embedded in the ground for the purpose of making connection with
the general mass of earth is known as earth electrode and the wire
which connects overhead. There are three types of artificial
electrodes: Driven electrodes: The electrode is made of metal rod
or pipe having a clean surface line. Rod electrodes of steel or
iron should have diameter of 16mm and those of copper at least
12.5mm. Strip electrodes: These are made of copper strips of area
25mmX1.6mm in cross section. They are buried under the ground not
less than 2.5m. Plate electrodes: A plate of copper or galvanized
iron of 0.6X0.6X0.006m for iron and 0.6X0.6X0.003m for copper is
buried with the face vertical in an alternate layer of coke and
salt.
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3.1.2 Earthing lead or main earthing conductor The main wire
that connects the earth electrode with main circuit board or the
earth wire running through distribution, transmission lines is
known as earthing lead. 3.1.3 Sub-main earthing conductor The earth
wire that runs between the main switch board to the distribution
board. 3.1.4 Earthing continuity conductor The wire running between
the distribution board to the various plugs and appliances. 3.2
Factors on which earth resistance depends a. Materials of
electrodes and earth wire. b. Size of electrode and earth wire. c.
Temperature of the soil. d. Moister of the soil. e. Depth to which
it is embedded. f. Quantity of coal and charcoal in the earth
electrode pit. Maximum value at the earthing side should be 5 ohms.
But for substations it should be of 0.5 to 1.00 ohms. 3.3 Methods
of earthing 3.3.1 Earthging through a water main Here a water main
is used as earth electrode.
3.3.2 Pipe earthing If water main is not available then a
galvanized pipe can be used. Its length should be 2.75m for wet
soil and 2.75m for dry soil. Alternate layers of coke and salt is
used around the earth electrode for best result. In summer season
it may be necessary to pour buckets of water to decrease the
resistance value. 3.3.3 Plate earthing Here, earthing connection is
provided via copper plate of size 60cmX60cmX6.35mm or G.I. pipe of
size 60cmX60cmX3.18mm. Use of copper plate is limited nowadays.
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EEE 314 Lecture 3 Prepared by: Md. Itrat Bin Shams (Sanin)
Contents 1 Safety Rules 2 1.1 Laboratory safety . . . . . . . .
. . . . . . . . . . . . . . . . . 2 1.1.1 Safety of person . . . .
. . . . . . . . . . . . . . . . . . 2 1.1.2 Safety of equipments .
. . . . . . . . . . . . . . . . . . 2 1.2 Additional items related
to personal and equipment safety 3 2 Sub-Stations 4 2.1
Classification of sub-stations . . . . . . . . . . . . . . . . . .
. 4 2.1.1 In accordance with the service . . . . . . . . . . . . .
. 4 2.1.2 In accordance with the service voltage . . . . . . . . .
4 2.1.3 In accordance with mounting . . . . . . . . . . . . . . 4
2.2 Essential parts of a sub-station . . . . . . . . . . . . . . .
. . 5 2.2.1 Transformer . . . . . . . . . . . . . . . . . . . . . .
. . 5 2.2.2 Insulators . . . . . . . . . . . . . . . . . . . . . .
. . . 6 2.2.3 Conductors . . . . . . . . . . . . . . . . . . . . .
. . . 7 2.2.4 Isolators . . . . . . . . . . . . . . . . . . . . . .
. . . . 7 2.2.5 circuit breakers . . . . . . . . . . . . . . . . .
. . . . . 7 2.2.6 Load interrupt switches . . . . . . . . . . . . .
. . . . 7 2.2.7 Power transformers . . . . . . . . . . . . . . . .
. . . . 8 2.2.8 Current transformers . . . . . . . . . . . . . . .
. . . . 8 2.2.9 Potential transformer . . . . . . . . . . . . . . .
. . . . 8 2.2.10 Carrier current equipment . . . . . . . . . . . .
. . . . 8 2.2.11 Control cables . . . . . . . . . . . . . . . . . .
. . . . . 8 2.2.12 Air break and disconnect switch . . . . . . . .
. . . . . 8 2.2.13 Switch board . . . . . . . . . . . . . . . . . .
. . . . . 8 2.2.14 Control room . . . . . . . . . . . . . . . . . .
. . . . . 9 2.3 Advantage and disadvantage of outdoor substation as
compared to indoor substation . . . . . . . . . . . . . . . . . . .
. 9 2.4 Design of a substation . . . . . . . . . . . . . . . . . .
. . . . 9 2.5 Layout of substations . . . . . . . . . . . . . . . .
. . . . . . . 10 2.5.1 Single Busbar . . . . . . . . . . . . . . .
. . . . . . . . 10 2.5.2 Mesh Substation . . . . . . . . . . . . .
. . . . . . . . 11 2.5.3 One and a half Circuit Breaker layout . .
. . . . . . . 11 2.6 BBT (Bus Bar Trunking) . . . . . . . . . . . .
. . . . . . . . . 12 2.6.1 Protection of BBT . . . . . . . . . . .
. . . . . . . . . 12
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1 Safety Rules
1.1 Laboratory safety While working in a laboratory, safety of a
person and equipment is necessary. These are discussed separately.
1.1.1 Safety of person The flow of electricity can adversely effect
anyones body in at least three ways. It causes muscle spasms and
paralysis. It can electrolyte blood in body and make bubbles. It
also can burn skin. Only 50mA current is enough for paralysis of
heart. What can be done if anyone is shocked: 1. The cause of shock
must be removed first. it is necessary to use nonconducting
materials such as woods or plastic to remove live wires or
substances from ones touch. 2. If the person shocked is not
breathing, artificial respiration should be given to him. 3. If the
victim is conscious, he should be in comfortable situation and
taken to a doctor. Precautions to prevent shocking: 1. One should
avoid become a victim. Voltages should not be allowed to come in
contact with the body. 2. No bare conductors should be touched
without knowing what it really stands for. How can a person get
shocked: 1. Any person needs only one conductor and a ground to get
shocked. This means if anyone touches a live wire a circuit is
formed through his body. Current can easily pass through him. 2.
There are a lot of capacitors in a house. These instruments can
hold charges for a long time. If anyone touches them he can get a
surprise shock. Skin posses a small resistance value. When a dry
skin comes across a contact, shock may be mild. But a sweaty skin
can produce a larger shock. A fat persons probability to get shock
is more than a light person as thin body has high resistance. There
are some non-electrical hazards around electrical and electronic
equipments. Like some batteries can discharge chemical materials
that is harmful for health. These batteries can produce explosive
hydrogen gases. Cathode-ray tubes are used in some electrical
appliances. These tubes have high pressure inside them. Pressure is
around 15 pounds per square inch. If it explodes due to some
mis-operation, then it is possible that broken glasses from tube
will move with high velocity and injure people. 1.1.2 Safety of
equipments About all general electrical instruments work with
constant voltage. So amount of current passing through them depends
on load resistive value. If it is small current is large and if it
is large current is small. Power consumed by any equipment thus
depends on current. Things are damaged if too much current passes
through them. Fuses and circuit breakers are provided to protect a
system. But they are usually provided to
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3
protect transmission lines. Fuses and circuit breakers operate
within fraction of a second. A lot of damages can be done within
this time to electrical equipments. Some ways to avoid common types
of troubles are: 1. Rated wires should be used so that it can carry
right amount of current of necessary. Resistor values should be
maintained to that value where safe operation os possible. 2.
Indicating and metering instruments should be handled according to
usual procedure. Such as a voltmeter has a high resistance and a
small current will flow through it. So voltmeters should be
connected in parallel to others. 3. Ammeters must be connected in
series in any circuit. As they have low resistance. To distinguish
the connection between voltmeter and ammeter, we can use the word
voltage across and current through. Ammeters can be kept in safe by
using ammeter shunt switches. If a huge current tend to flow
through the ammeter shunt switch will be off and ammeter will be
safe. 1.2 Additional items related to personal and equipment safety
Meters should be kept in their highest position before energizing a
circuit. It is important that meters be hooked up with correct
polarity. Resistors should have power ratings at least two times
greater than expected power dissipation. If it is necessary to
change a certain portion of a circuit, it is recommended that all
the parts be energized. In all cases voltage sources should not be
applies to desired point suddenly. It should be brought up from
zero value to highest value slowly. There should be a first aid kid
box for every lab in case of minor cuts and burns. If fuses are
blown out, correct rated fuses must be replaced in place of older
one. All labs should have decade resistance boxes and resistor
substitution boxes. Decade resistor boxes are provided to make
estimation of unknown resistor values. Resistor substitution boxes
are used in hooks up where resistances are altered. Ohmmeters
should be turned off after use. This will make sure of linger
battery life. Any malfunctioing instrument should not be repaired
by untrained personnel. Fire hazards or burns can result from poor
soldering equipments. Poor insulation can make high current to flow
as well as starting fire. Resistors and other equipments should not
be altered if circuit is energized. Burnt out florescent bulbs
should be replaced carefully as there is a chemical coating inside
the bulb. Prevent dangerously high voltage, reverse winding
connection of transformers must not made. Commercial transformers
should be properly ventilated. Neutralization of any acid or
battery electrolyte that may get on clothing must be made. When
acid and water is mixed, acid must be poured in water.
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2 Sub-Stations
A sub-station can be defined as combination of apparatus that
transforms the characteristics of electrical energy from one form
to other form. For example, from alternating to DC or from one
level of voltage to other. 2.1 Classification of sub-stations
Sub-stations can be classified on the basis of some features. They
are: 2.1.1 In accordance with the service Static: The instruments
used to change electrical energy characteristics are static. So it
changes voltage of an a.c signal. Converting: In this type A.C.
energy is changed to D.C. energy. 2.1.2 In accordance with the
service voltage Extra high voltage: Here voltage level is changed
in the range of 66kV in order to transmit energy. It is also called
transmission sub-station. Distribution Sub-station: In this
sub-station voltage is stepped down to 400 volts. Industrial
sub-station: Different industries need different voltage levels to
make their machines work. Industries take power from 11kV or 66kV
feeder line and then convert the voltage level according to their
need via industrial substation. Substation for power factor
correction: Due to the presence of inductance power factor falls at
the end of the transmission line. In order to improve power factor,
synchronous condensers are used. Such installations are known as
power factor correction sub-station. Frequency changing
sub-stations: These sub-stations are used to change frequency of
one signal to another value. 2.1.3 In accordance with mounting
Indoor type substation: These sub-stations are used with open and
enclosed chambers or compartments. The chamber space in which one
main bus bar connection is mounted is called cell, cubicle or
compartment. These sub-stations are built to handle voltage up to
11000 volts but can also be used to operate in 33000 or 66000
volts. Surrounding air in this type of installation is filled with
dust, gases and fumes. According to construction indoor type
substations can be further divided into: Sub-stations with
integrally built type: Here apparatus are installed in site. Cell
structure is constructed with concrete or brick. Sub-stations with
composite built type: A switchgear room is provided for control.
Compartments of these sub-stations are taken from metal cabinets or
enclosures, each of which contains the equipment of one main
connection cell. Unit type factory fabricated sub-stations: It is
fully preassembled. After installation only incoming and outgoing
connections are to be provided.
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Outdoor type sub-stations: These are of two types. Pole mounted
substation: These are installed on certain poles. They are of
H-pole and 4-pole. They carry transformers of capacity up to
200kVA. These types of sub-stations are cheap, simple and smaller.
Foundation mounted sub-station: These sub-stations are used to
handle primary and secondary transmission. As they carry huge
machineries so it is necessary to place them in such a site where
there is sufficient access of heavy transport.
2.2 Essential parts of a sub-station 2.2.1 Transformer
Transformers are mainly used in voltage conversion purposes. A
transformer has primary and secondary coils and they are insulated
from each other by insulation. There is a steel core which is made
of laminations. Transformers are placed in a container and
transformer oil is placed between the container and transformer to
make sure of insulation. Transformers are divided according to two
categories. In accordance with the type of core: It is again
divided into two parts. Core type transformer: Here low voltage
winding is provided near the core. It is because low insulation is
needed for low voltage side.
Shell type transformer: Here shell type core is provided.
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In accordance with the type of cooling: Here transformers are
again subdivided in following categories. Oil filled self cooled:
Here a type of insulating oil is provided for cooling purposes. Oil
provided must be of high quality and it should be replaced after
specific periods of time. Oil-filled water cooled: Here oil that is
used for cooling purpose is cooled by water coils circulating
inside the container. Here convection method of heat transfer is
used. Air blast type: It is used for transformers of capacity 33kV
or above. Strong air is directed towards the transformer coil
through ducts. 2.2.2 Insulators The porcelain insulators used in
sub-station are of post and bushing type. They serve as both
support and insulation purpose. Post type: A post insulator
consists of porcelain body, cast iron cap and flanged cast iron
body. Bus bars are bolted to the cap either directly or fixed by
means of a bus bar clamp.
Figure 3: Post type insulator
Bushing type: It consists of porcelain shell body, upper and
lower locating washers and mounting flange. They are designed to
handle currents above 2000A.
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2.2.3 Conductors The substation buses can be of the following
types: a. Rigid buses of solid conductor or tubing. b. Strain bus
of cables. An ideal conductor should fulfill the following
requirements:
a) Should be capable of carrying the specified load currents and
short time currents b) Should be able to withstand forces on it due
to its situation. These forces
comprise self weight and weight of other conductors and
equipment, short circuit forces and atmospheric forces.
c) Should be corona free at rated voltage. d) Should have the
minimum number of joints. e) Should need the minimum number of
supporting insulators. f) Should be economical
Nowadays aluminium is used over copper wires. It is because
aluminium has higher conductivity, lower cost for equal current
carrying capacity, excellent corrosion resistance and ease of
formability. 2.2.4 Isolators Isolators are used to isolate a
certain portion of a system after switching of circuit breakers.
Sometimes isolators are used to operate as a circuit breakers but
their operation as this is strictly limited due to certain
conditions. Isolators are of two types, Single pole isolators.
Three pole isolators. Isolator design is considered in the
following aspects:
1) Space Factor 2) Insulation Security 3) Standardization 4)
Ease of Maintenance 5) Cost
2.2.5 circuit breakers Circuit breakers are intended to perform
the following tasks: 1. To carry the full load current
continuously. 2. To open and close the circuit on no load. 3. To
make and break the normal operating current. 4. To make and break
the short circuit current of magnitude up to which it is designed
for. 2.2.6 Load interrupt switches They are used to open and close
high voltage circuits. They should be handled carefully.
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2.2.7 Power transformers Power transformers are used to step up
voltage at generation end for transmission purpose and step down
voltage for farther distribution of power. Different types of
transformers such as, naturally cooled, oil immersed, two winding
three phase transformers, air blast cooled transformers are used.
Power transformers are usually the largest single item in a
substation. Because of the large quantity of oil, it is essential
to take protection against the spread of fire. Hence, the
transformer is usually located around a sump used to collect the
excess oil. 2.2.8 Current transformers Current transformers are
used in indicating and metering instruments. They are used in
ammeters, wattmeter, watt-hour meter etc. Primary coils of these
transformers are placed in the circuit where current is ti be
measured. Secondary coil takes current reading in a suitable value
so that indicating instrument can show the reading. 2.2.9 Potential
transformer Potential transformers are also used in metering and
indicating instruments such as voltmeter, wattmeter, watt-hour
meter. Primary coil is directly connected to busbars where voltage
is to be measured. Secondary coil converts the voltage reading to a
suitable value so that indicating instrument can show this in full
scale. 2.2.10 Carrier current equipment These are used for
communication, relaying, telemetering and supervisory control.
2.2.11 Control cables To carry different voltage levels, different
cables (say 10 or 37 or 61 conductor grouped cables) are used. It
is necessary to control these cables inside a conduit. For this,
control cables are provided. Ducts are used to run from switch gear
rooms to the beginning and end of a conduit. 2.2.12 Air break and
disconnect switch For lines with 46kV or lower voltages, disconnect
switches are provided with single pole construction and hook stick
operated mechanism. For 110kV or upper voltage systems group
operated mechanism is provided where all the six poles are operated
with one handle. 2.2.13 Switch board Switch boards are consisted
with meters, relays and control equipments. The essential meters
are placed at the bottom. Control equipment half way through, so as
to facilitate operation. It is shown in following figure.
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2.2.14 Control room A control room is provided to monitor all
the readings and to have an excess to all connection points.
Normally an operator is given for each control room.
2.3 Advantage and disadvantage of outdoor substation as
compared to indoor substation The outdoor substation has
following advantages: The construction work needed is much smaller
than the indoor substation. Installation cost of switchgear is low.
Adequate space between two adjoining equipment can be provided.
Erection is made in less time. Whole structure is properly viewed,
so that fault can be easily located. The scheme extension is
easier. Disadvantages of outdoor substations are, Dust and dirt use
to formulate on contact switches. This makes maintenance cost
higher. In rainy or snow falling seasons switching becomes
complicated. The installation suffers from security as unauthorized
persons can easily penetrate the structure.
2.4 Design of a substation Following steps should be followed in
designing a substation: 1. Make a single line diagram of the total
system showing all the connection between bus bars, circuit
breakers and reactors. 2. Design the layout of the switchgear
depending on the size, capacity of the substation. 3. Circuits
should be designed in such a way that minimum amount of risk will
occur in case of its failure. 4. The layout should be such that any
faulty section can be isolated without effecting the other
portions. 5. There should be provision for easy and safe excess for
maintenance and repairing purpose.
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6. Partitions should be provided in order to differentiate one
part from other. 7. Reactors must be of rating that can limit the
short circuit current. This makes capacity of the circuit breaker
adequate. 8. To avoid using huge circuit breakers the current per
circuit breaker should be limited to 2000A. 9. Fire extinguishing
system must be provided. 10. The earth conductor should have
sufficient capability to carry any amount of fault current. 11.
Automatic electric gear should be given. 12. Power cables should be
separated from control cables. 13. In order to avoid fire hazard,
fire proof control room and switch room have to be provided. 14.
Arrangement for oil handling must be safe.
2.5 Layout of substations There can be different layouts of a
substation. Three are given below: 2.5.1 Single Busbar Layout is
given in figure 6. Operation is very simple in this layout design.
But its reliability is very low as if bus goes out of service all
the loads will be disconnected from power supply. There is a
provision to support cheap future connection of feeders. Some
features of this scheme are, Each circuit is protected by its own
circuit breaker and hence plant outage does not necessarily result
in loss of supply. A fault on the feeder or transformer circuit
breaker causes loss of the transformer and feeder circuit, one of
which may be restored after isolating the faulty circuit breaker. A
fault on the bus section circuit breaker causes complete shutdown
of the substation. All circuits may be restored after isolating the
faulty circuit breaker. Maintenance of a feeder or transformer
circuit breaker involves loss of the circuit. Introduction of
bypass isolators between busbar and circuit isolator allows circuit
breaker maintenance facilities without loss of that circuit.
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2.5.2 Mesh Substation Layout of this scheme is given in figure
7. Some characteristics are, Operation of two circuit breakers is
required to open or close a circuit. Circuit breakers may be
maintained without loss of supply or protection, and no additional
bypass facilities are required. Breaker faults will involve the
loss of a maximum of two circuits.
2.5.3 One and a half Circuit Breaker layout The reason that such
a layout is known as a 1 and 1/2 circuit breaker is due to the fact
that in the design, there are 9 circuit breakers to protect the 6
feeders. Thus, 1 and circuit breakers protect 1 feeder. Some
characteristics of this design are: Here arrangement is complex and
it is also expensive. There is provision to operate one circuit or
group of circuits. reliability is very high in case of loss of
power.
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2.6 BBT (Bus Bar Trunking)
Bus bar trunking is used to increase the current carrying
capability of a system. Here multiple buses are used in
parallel.
This Unified Recommendation is for the test and installation of
busbar trunking systems arranged outside of switchboards for
supplying section or distribution boards or consumers, instead of
cables. They are not recommended to be installed in hazardous areas
or on the exposed weather deck. 2.6.1 Protection of BBT General
Systems should comply with the specific requirements of local
electrical codes. Temperatures should be in the range from 0 to
45oC. Nearby foreign bodies or water pipes must be placed away from
bus bars to protect them. The system should be designed to
withstand a vibration level of 1mm amplitude in the frequency range
of 2 Hz to 13.2 Hz and of 0.7g acceleration in the frequency range
of 13.2 Hz to 100 Hz. It should be suitable for automatic draining
where condensation is possible. Fire test arrangements should be
compatible with the local codes.
Revised by Shama Naz Islam, Lecturer, EEE, BUET
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CONTENTS
EEE 314 Lecture 4
Prepared by: Md. Itrat Bin Shams (Sanin)
Contents
1 Home security and fire alarm system 21.1 Types of sensors . .
. . . . . . . . . . . . . . . . . . . . . . . . 21.2 The alarm
system . . . . . . . . . . . . . . . . . . . . . . . . . 31.3
Digital security pad . . . . . . . . . . . . . . . . . . . . . . .
. 31.4 Fire alarms for the home . . . . . . . . . . . . . . . . . .
. . . 4
1.4.1 Heat detectors . . . . . . . . . . . . . . . . . . . . . .
. 51.4.2 Smoke detectors . . . . . . . . . . . . . . . . . . . . .
. 6
2 Television connection 62.1 Typical problems with antenna . . .
. . . . . . . . . . . . . . 6
2.1.1 Congested area problem . . . . . . . . . . . . . . . . .
62.1.2 Fringe area problems . . . . . . . . . . . . . . . . . . .
6
2.2 Cable television wire . . . . . . . . . . . . . . . . . . .
. . . . 6
3 Telephone wiring 63.1 Telephone regulation . . . . . . . . . .
. . . . . . . . . . . . . 73.2 Number of telephones that can be
connected . . . . . . . . . . 83.3 Safety consideration . . . . . .
. . . . . . . . . . . . . . . . . . 8
4 Burglar alarm 94.1 Access Control . . . . . . . . . . . . . .
. . . . . . . . . . . . 94.2 A simple sound activated burglar alarm
system . . . . . . . . 10
5 CCTV 105.1 INTRODUCTION . . . . . . . . . . . . . . . . . . .
. . . . . 105.2 THE CAMERA . . . . . . . . . . . . . . . . . . . .
. . . . . . 115.3 THE MONITOR . . . . . . . . . . . . . . . . . . .
. . . . . . 115.4 SIMPLE CCTV SYSTEMS . . . . . . . . . . . . . . .
. . . . 11
6 Sprinkler 126.1 Fire sprinkler . . . . . . . . . . . . . . . .
. . . . . . . . . . . 12
7 Elevators 15
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1. Home security and fire alarm system
8 Intercom 168.1 Types of intercoms . . . . . . . . . . . . . .
. . . . . . . . . . 16
8.1.1 Two wire . . . . . . . . . . . . . . . . . . . . . . . . .
168.1.2 Four wire . . . . . . . . . . . . . . . . . . . . . . . . .
16
9 Air conditioning 179.1 Introduction . . . . . . . . . . . . .
. . . . . . . . . . . . . . . 179.2 Air conditioning application .
. . . . . . . . . . . . . . . . . . 18
9.2.1 Comfort application . . . . . . . . . . . . . . . . . . .
189.2.2 Process application . . . . . . . . . . . . . . . . . . . .
18
9.3 Basic principle of air conditioning . . . . . . . . . . . .
. . . . 19
10 Local area network (LAN) 20
11 Home heating system 2111.1 Types of home heating systems . .
. . . . . . . . . . . . . . . 21
11.1.1 Traditional Furnaces . . . . . . . . . . . . . . . . . .
. 2111.1.2 Electric Heat Pump . . . . . . . . . . . . . . . . . . .
. 2111.1.3 Radiant Baseboard Heat . . . . . . . . . . . . . . . . .
2111.1.4 Radiant Ceiling or Floor Heat . . . . . . . . . . . . . .
22
1 Home security and fire alarm system
For home security system following sensors are used.
1.1 Types of sensors
Foil type sensors on windows that works if someone penetrates
throughit.
Magnetic or push button switch on a door or window frame. Panic
buttons placed at strategic locations that are pushed to
activatethe alarm system.
Heat detectors and smoke detectors to protect a house. High
temperature heat detector. Various types of detectors for vibration
detection, infrared or ultrasonicmotion detector, low temperature
detector to indicate a home is losingheat, pressure sensing
detector under a carpet or floor.
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1.2 The alarm system
1.2 The alarm system
There is a central alarm center that is used to monitor all the
alarms in ahome. Sometimes there is a automatic telephone dialer in
a home, that isused to call the police in case of unknown intruder.
the around-the-clockservice can be used which indicates what type
of alarm is being initiated.All these are controlled by central
alarm system.
There are two basic circuits used for sensing purposes. They are
normallyclosed and normally open.
1. Normally Closed (NC): Normally closed circuits are closed
when inactive mode. If somehow it is opened then alarm is
initiated. A goodexample of it is sensors used in windows and
doors. Here if the widowor door is closed the two contact path in
the circuit are intact. But ifsomeone opens it contact is broken,
as a result alarm is triggered.
2. Normally Open (NO): Normally open circuits are opened while
in activemode. If it is closed then alarm is initiated. It is used
in pressuresensing for example. When someone sits on a sofa two
contact pathesin the sensing circuit are closed. As a result alarm
is On.
Another type of sensing available is delayed sensing. It is used
to initiatealarm after a certain time of sensing circuit operation.
It is used in fire alarmsystem where there is a time delay before
the doors are closed in a space.
1.3 Digital security pad
In fig. 1 a typical digital security pad is shown. It allows
some time to makean alarm system armed so that the user can safely
leave the place coveredby the system without initiating the
alarm.
There are three lights. Red light blinking means activity is
reported andit will continue to do so until someone clears the
system. Green light blinkswhen a sensor goes to an abnormal
position, such as a windows opening.Yellow light is lit if one or
more sensors are shunted out.
To remove the shunt, the sensors should first be removed to
normal posi-tion and the secret code be entered. The green light
will be out and red andyellow light will be in steady position. If
the secret code is entered again,
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1.4 Fire alarms for the home
Figure 1: Digital security pad
red and yellow light will be out and green light will glow to
indicate normalposition of sensors. In case of shunted sensors,
full system may not returnedto its normal position. For this red
light will go out when secret code isentered, but green light will
blink to show shunted out sensors. A blinkinggreen light always
indicates an abnormal condition and the number of blinksindicate
what type of condition it is.
1.4 Fire alarms for the home
This alarm system can be of stand alone type or conjuncted with
centralalarm system. The stand alone type can be a smoke detector
but not aheat detector. There are two types of detector: one that
detects amountof radioactive material called ionization type, and
another is optical sensingtype.
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1.4 Fire alarms for the home
1.4.1 Heat detectors
Heat detector has a vital limitation. In most of the cases heat
detectors areactivated after smoke, fire hazard reaches above
tolerance limit.
Figure 2: Flush mounting
Figure 3: Wiring in a heat detector
A typical flush mounting heat detector is shown in fig. 2.
Wiring con-nection of a heat detector is shown in 3. There is a
plasticizing material. Ifsomehow it penetrates beyond the terminal
screws into the interior of theunit or beyond the plastic discs
into the raised vent opening, the calibrationof the rate of rise
feature will be altered, usually resulting in a false alarm.
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2. Television connection
1.4.2 Smoke detectors
Smoke detectors detect any presence of smoke in a room. There
are basicallytwo types of smoke detectors.
1. Ionization detector: When the detector is connected to power
source aradioactive material can ionize the air between two
electrodes.
2. Photoelectric detector: There is a light source and a
photocell. Innormal condition no light falls on the photocell. When
smoke particlesenter the chamber, it causes light to reflect on the
photocell.
2 Television connection
2.1 Typical problems with antenna
2.1.1 Congested area problem
If high congestion of signals exist in a area, it is possible to
achieve betterresult by having co-axial lead in cables.
2.1.2 Fringe area problems
Fringe area problem exist if strength of the signal arriving
from the trans-mitter is weak. It can have noises, interferences,
flutter and ghosts. It canbe reduced by using reflectors and
director elements or antenna boosters.Also higher the receiving
antenna is better is the chance to receive the signalcorrectly.
2.2 Cable television wire
For new building construction, the electrical contractor who
installs housewiring usually installs the co-axial cable and TV
outlets. It is essential thatelectricians be familiar with type
RG59/U TV co-axial cable requirement.The co-axial cable must have a
type F59 coaxial connector installed on itsend to permit it to be
connected for use. In figure one type of connector isshown.
3 Telephone wiring
Making modification to any home telephone system is simple, safe
and inex-pensive. So telephone wiring is not that complex.
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3.1 Telephone regulation
Figure 4: Cable prepared for connector
3.1 Telephone regulation
Telephone company will maintain all the responsibility for the
wire from theircentral office to the point indicated in the figure.
It may also be requiredthat their should be some sort of
disconnecting option from the main line tohome. For this purpose
existing outlets or modular jack are used. In mostof the cases
network interface is used.
Figure 5: Point of demarcation
Telephone company can give a network interface if it is required
by thecustomer. It is very convenient way to be connected to the
telephone com-panys services. If repair to the line is needed
interface can be disjointed and
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3.2 Number of telephones that can be connected
Figure 6: Network interface
all the phones in the home will be disconnected from main
line.
3.2 Number of telephones that can be connected
Each phone needs a ringing power known as ringer equivalency
number(REN). If number of phones connected in a home has REN
summation lessthat 5, there will be no problem. But if it is more
than 5 then not all thephones can be connected simultaneously. In
this case phones with lower RENvalues have to be used.
3.3 Safety consideration
Though telephone lines usually carry a low current, it is
necessary to performsome precautions while working with them.
A telephone must be disconnected before working with it.
Thoughtelephones carry a little current, to ring the phone a
slightly morecurrent is needed. So anyone may get a surprised shock
while thephone rings.
Wires and screws should not be touched.
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4. Burglar alarm
When a thunderstorm or lighting is nearby, no one should work
withtelephone lines.
Persons with pacemakers shold not work with telephone lines.
Telephones with lighted dials usually draw powers from telephone
lines.But some use to do it by a little transformer. It should be
disconnectedbefore working.
Telephones are not to be used near water. If walls are to be
drilled or cut, cautions must be taken so that nointernal pipes are
cut.
There should be no loose wires. They can introduce severe
hazards.
4 Burglar alarm
Burglar (or intrusion), fire and safety alarms are found in
electronic form to-day. Sensors are connected to a control unit via
either a low-voltage hardwireor narrowband RF signal, which in turn
connects to a means for announcingthe alarm, hopefully to elicit
some response. The most common security sen-sors indicate the
opening of a door or window or detect motion via passiveinfrared
(PIR). In new contsruction systems are predominately hardwiredfor
economy while in retrofits wireless systems may be more economical
andcertainly quicker to install. Some systems are dedicated to one
mission, oth-ers handle fire, intrusion, and safety alarms
simultaneously. Sophisticationranges from small, self-contained
noisemakers, to complicated, multi-zoneddigital systems with
color-coded computer monitor outputs. Many of theseconcepts also
apply to portable alarms for protecting cars, trucks or
othervehicles and their contents.
4.1 Access Control
Access Control and Bypass Codes To be useful, an intrusion alarm
system isdeactivated or reconfigured when authorized personnel are
present. Autho-rization may be indicated in any number of ways,
often with keys or codesused at the control panel or a remote panel
near an entry. High-securityalarms may require multiple codes, or a
fingerprint, badge, hand-geometry,retinal scan, encrypted response
generator, or other means that are deemedsufficiently secure for
the purpose. Failed authorizations should result in analarm or at
least a timed lockout to prevent experimenting with possible
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4.2 A simple sound activated burglar alarm system
codes. Some systems can be configured to permit deactivation of
individualsensors or groups. Others can also be programmed to
bypass or ignore indi-vidual sensors (once or multiple times) and
leave the remainder of the systemarmed. This feature is useful for
permitting a single door to be opened andclosed before the alarm is
armed, or to permit a person to leave, but notreturn. High-end
systems allow multiple access codes, and may even permitthem to be
used only once, or on particular days, or only in combination
withother users codes (i.e., escorted). In any case, a remote
monitoring centershould arrange an oral code to be provided by an
authorized person in caseof false alarms, so the monitoring center
can be assured that a further alarmresponse is unnecessary. As with
access codes, there can also be a hierarchyof oral codes, say, for
furnace repair person to enter the kitchen and base-ment sensor
areas but not the silver vault in the butlers pantry. There arealso
systems that permit a duress code to be entered and silence the
localalarm, but still trigger the remote alarm to summon the police
to a robbery.
4.2 A simple sound activated burglar alarm system
Figure 7: Simple burglar alarm
5 CCTV
5.1 INTRODUCTION
As the name implies, it is a system in which the circuit is
closed and all theelements are directly connected. This is unlike
broadcast television whereany receiver that is correctly tuned can
pick up the signal from the airwaves.Directly connected in this
context includes systems linked by microwave,infrared beams,
etc.
10
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5.2 THE CAMERA
5.2 THE CAMERA
The starting point for any CCTV system must be the camera. The
cameracreates the picture that will be transmitted to the control
position. Apartfrom special designs CCTV cameras are not fitted
with a lens. The lens mustbe provided separately and screwed onto
the front of the camera. There is astandard screw thread for CCTV
cameras, although there are different typesof lens mounts.
Figure 8:
5.3 THE MONITOR
The picture created by the camera needs to be reproduced at the
controlposition. A CCTV monitor is virtually the same as a
television receiverexcept that it does not have the tuning
circuits.
5.4 SIMPLE CCTV SYSTEMS
The simplest system is a camera connected directly to a monitor
by a coaxialcable with the power for the camera being provided from
the monitor. Thisis known as a line powered camera.
The next development was to incorporate the outputs from four
camerasinto the monitor. These could be set to sequence
automatically through thecameras or any camera could be held
selectively.
The basic CCTV installation is shown where the camera is mains
poweredas is the monitor. A coaxial cable carries the video signal
from the camera tothe monitor. Although simple to install it should
be born in mind that the
11
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6. Sprinkler
Figure 9:
Figure 10:
installation must comply with the relevant regulations such as
the Instituteof Electrical Engineers latest edition.
6 Sprinkler
6.1 Fire sprinkler
Fire sprinklers are an active fire protection measure subject to
stringentbounding. They are connected to a fire suppression system
that consists ofoverhead pipes fitted with sprinkler heads
throughout the coverage area. Fire
12
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6.1 Fire sprinkler
Figure 11:
Figure 12:
sprinkler systems for high-rises are usually also equipped with
a fire pump,and a jockey pump and are tied into the fire alarm
system.
Each sprinkler head is held closed independently by
heat-sensitive seals.
13
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6.1 Fire sprinkler
Figure 13:
Figure 14:
These seals prevent water flow until a design temperature is
exceeded atthe individual sprinkler heads. Each sprinkler activates
independently whenthe predetermined heat level is reached. The
design intention is to limitthe total number of sprinklers that
operate, thereby providing the maximumwater supply available from
the water source to the point of fire origin.
14
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7. Elevators
7 Elevators
An elevator is a transport device used to move goods or people
vertically. InCommonwealth English, elevators are more commonly
called lifts. Becauseof wheelchair access laws, elevators are often
a requirement in new buildingswith multiple floors.
Elevators are of two types, hydraulic and traction. The
hydraulic elevatorconsists of a cab attached to the top of a
hydraulic jack similar to a jackused for a car lift in a service
station. The hydraulic jack assembly normallyextends below the
lowest floor and is operated by a hydraulic pump andreservoir, both
of which are usually located in a separate room adjacent tothe
elevator shaft, as shown in Figure. Hydraulic elevators are the
typegenerally used in single-family residences. The second type is
the tractionelevator. This is the system that is most commonly
associated with elevators.The traction system consists of a cable
that is connected to the top of thecab and is operated by an
electric motor located in a penthouse above theelevator shaft, as
shown in Figure.
Figure 15:
15
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8. Intercom
8 Intercom
An intercom is an electronic communications system within a
building orgroup of buildings. Intercoms are generally composed of
fixed microphone/speakerunits which connect to a central control
panel. A small home intercom mightconnect a few rooms in a house.
Larger systems might connect all of therooms in a school or
hospital to a central office. Intercoms in larger buildingsoften
function as public address systems, capable of broadcasting
announce-ments. In many schools, tones signaling the change of
classes are soundedover the intercom, taking the place of the
electromechanical bells used inolder schools. Intercom systems can
also be found on passenger and rapidtransit trains.
8.1 Types of intercoms
8.1.1 Two wire
Two-wire Intercom systems are widely used in TV stations and
outside broad-cast vehicles such as those used at sporting events
or entertainment venues.There are essentially two different types
of intercoms used in the televisionworld, Two-Wire party lines or
Four-Wire matrix systems. In the beginningof TV broadcasting
stations would simply build their own communicationsystems using
old phone equipment, however, today there are several
man-ufacturers of off the shelf systems. From the late 70s until
the mid 90sthe two-wire party line type systems were the most
popular primarily dueto the technology that was available at the
time. They used a central powersupply to drive external stations or
belt packs. These systems were veryrobust and simple to design,
maintain and operate but had limited capacityand flexibility as
they were usually hardwired. This meant that a user onthe system
could not choose who to talk to, rather, they were always talkingto
the same person or group of people until the system was
reconfigured toallow communication with a different group of
people.
8.1.2 Four wire
Four-wire In the mid-90s Four-Wire technology started gaining
more promi-nence due to the technology getting cheaper and smaller.
Four-wire technol-ogy had been around for quite some time but was
very expensive to imple-ment and usually required a large footprint
in the physical TV Plant thuswas only used at very large stations
or TV networks. Also, the large phys-ical size made it virtually
impossible to use on a mobile platform such asan outside broadcast
vehicle. The term four-wire comes from the fact that
16
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9. Air conditioning
the system uses a transmit pair and a receive pair for the audio
to and fromthe intercom; four wires. That said, in a modern
four-wire system there areactually six wires; two for data or a
data pair that make 5 and 6, neverthelessthe phrase has stuck and
this is the accepted term for these systems today.One major
advantage of these systems vs. the two-wire systems is the
abilityto do point to point communication at will.
Figure 16:
9 Air conditioning
9.1 Introduction
In the broadest sense air conditioning can refer to any form of
cooling, heat-ing, ventilation or disinfection that modifies the
condition of air, typicallyfor thermal comfort. The more common use
of air conditioning is to meancooling and often dehumidification of
indoor air, typically via refrigeration.
An air conditioner is an appliance, system, or mechanism
designed toextract heat from an area using a refrigeration cycle.
The most commonuses of modern air conditioners are for comfort
cooling in buildings andtransportation vehicles.
17
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9.2 Air conditioning application
9.2 Air conditioning application
9.2.1 Comfort application
Comfort applications aim to provide an indoor environment that
remainsrelatively constant in a range preferred by humans despite
changes in externalweather conditions or in internal heat
loads.
Low-Rise Residential buildings including single family houses,
duplexes,and small apartment buildings
Hi-Rise Residential buildings such as tall dormitories and
apartmentblocks
Commercial buildings which are built for commerce, including
offices,malls, shopping centers, restaurants, etc.
Institutional buildings includes hospitals, governmental,
academic, andso on.
Industrial spaces where thermal comfort of workers is
desired.
In addition to buildings, air conditioning can be used for
comfort in awide variety of transportation including land vehicles,
trains, ships, aircraft,and spacecraft.
9.2.2 Process application
Process applications aim to provide a suitable environment for a
process beingcarried out, regardless of internal heat loads and
external weather conditions.Although often in the comfort range, it
is the needs of the process thatdetermine conditions, not human
preference. Process applications include:
Hospital operating theatres in which air is filtered to high
levels toreduce infection risk and the humidity controlled to limit
patient dehy-dration. Although temperatures are often in the
comfort range, somespecialist procedures such as open heart surgery
require low tempera-tures (about 18 C, 64 F) and others such as
neonatal relatively hightemperatures (about 28 C, 82 F).
Cleanrooms for the production of integrated circuits,
pharmaceuticalsand the like in which very high levels of air
cleanliness and control oftemperature and humidity are required for
the success of the process.
18
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9.3 Basic principle of air conditioning
Facilities for breeding laboratory animals. Since many animals
nor-mally only reproduce in spring, holding them in rooms at which
condi-tions mirror spring all year can cause them to reproduce year
round.
Aircraft air conditioning. Although nominally aimed at providing
com-fort for passengers and cooling of equipment, aircraft air
conditioningpresents a special process because of the low air
pressure outside theaircraft.
Data processing centers Textile factories Physical testing
facilities Plants and farm growing areas Nuclear facilities Mines
Industrial environments Food cooking and processing areas
In both comfort and process applications the objective to not
only controltemperature, but also humidity, air movement, and air
quality.
9.3 Basic principle of air conditioning
In the vapor-compression refrigeration cycle, heat is
transferred from a lowertemperature source to a higher temperature
heat sink. Heat naturally flowsin the opposite direction, and due
to the second law of thermodynamics workis required to move heat
from cold to hot. A food refrigerator or freezer worksin much the
same way; it moves heat out of the interior into the room inwhich
it stands.
A diagram of the refrigeration cycle: 1) condensing coil, 2)
expansionvalve, 3) evaporator coil, 4) compressor.
19
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10. Local area network (LAN)
1
2
3
Figure 17:
10 Local area network (LAN)
A local area network (LAN) is a computer network covering a
local area, likea home, office, or group of buildings. Each node or
computer in the LAN hasits own computing power but it can also
access other devices on the LANsubject to the permissions it has
been allowed. These could include data, themore expensive devices /
less used resources that it would be impractical tohave multiple
copies of, and the ability to communicate or chat with otherusers
in the network.
Although switched Ethernet is now the most common data link
layerprotocol (OSI 7-Layer Model), and IP as a network layer
protocol, many dif-ferent options have been used (see below), and
some continue to be popularin niche areas. Smaller LANs consist of
a few switches typically connectedto each other and with one
connected to a router, cable modem, or DSLmodem. A traditional
model of access, distribution, and core switches waspopularized by
Cisco Systems and has been in use for many years.
Larger LANs are characterized by distributing Ethernet traffic
roles withinthe network. Each layer aggregates traffic of the layer
below it and will typi-cally maintain redundant links with switches
capable of quality of service andspanning tree protocol to prevent
loops and the recovery of failed uplinks.
20
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11. Home heating system
11 Home heating system
11.1 Types of home heating systems
11.1.1 Traditional Furnaces
A furnace draws air from the house into a ductwork system,
taking it to anarea where it is warmed before being delivered back
to living spaces. Newerfurnaces use blowers to recirculate the
warmed air. A furnace may be fueledwith gas, electricity, oil, or
even coal or wood.
Circulating air is drawn through a filter that helps rid the
house of dustand other particles.
Gas and oil furnaces have a pilot light that warms a heat
exchangeunit, which in turn warms the air before it is circulated
back throughthe house. These furnaces have a flue where exhaust
gases vent to theoutside.
An electric furnace uses heating strips, or elements, to warm
the air. A wood or coal furnace has a sealed firebox where the fuel
is burned,and a heat exchanger where air is warmed before
delivery.
Metal vents that allow warmed air to escape from the system and
intothe house are usually found in the floors or on walls in living
areas.
11.1.2 Electric Heat Pump
Heat pumps work by shuffling heat from one place to another.
They alsoserve as air conditioners during warm weather. Heat pumps
extract warmthfrom outdoor air, from ground or surface water, or
from the earth. The air iswarmed more by the system if necessary,
then circulated through the house.
11.1.3 Radiant Baseboard Heat
Baseboard heaters are often visible as long, metal units with
electrical ele-ments inside. Each unit has its own control, which
may be marked in incre-ments from low-to-high, but will not show
the rooms current temperature.
21
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11.1 Types of home heating systems
11.1.4 Radiant Ceiling or Floor Heat
Radiant systems warm objects in much the same way as the sun
does. Noblowers are used. Electric radiant elements are installed
in floors or ceilings.In the examples Ive seen, each area has a
dial control similar to the onesthat operate baseboard heating
units. Heating elements can also be installedin walls, but that
location is less common.
Hydrolic Heating is another type of radiant heat, where hot
water flowsthrough tubes under the floor or through units that
resemble baseboardheaters.
22
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CONTENTS
EEE 314 Lecture 5
Prepared by: Md. Itrat Bin Shams (Sanin)
Contents
1 LAN (Local Area Network) 11.1 Definition of LAN . . . . . . .
. . . . . . . . . . . . . . . . . . 11.2 LAN access method . . . .
. . . . . . . . . . . . . . . . . . . . 2
1.2.1 Carrier sense multiple access collision detect (CSMA/CD)
21.2.2 Token passing . . . . . . . . . . . . . . . . . . . . . . .
2
1.3 Some other informations . . . . . . . . . . . . . . . . . .
. . . 21.4 LAN Transmission Methods . . . . . . . . . . . . . . . .
. . . 2
1.4.1 Unicast transmission . . . . . . . . . . . . . . . . . . .
31.4.2 Multicast transmission . . . . . . . . . . . . . . . . . .
31.4.3 Broadcast transmission . . . . . . . . . . . . . . . . . .
3
1.5 LAN Topologies . . . . . . . . . . . . . . . . . . . . . . .
. . . 31.6 LAN Devices . . . . . . . . . . . . . . . . . . . . . .
. . . . . 4
2 Intercom 52.1 General Information . . . . . . . . . . . . . .
. . . . . . . . . 52.2 Some terms related to intercoms . . . . . .
. . . . . . . . . . . 62.3 Classification of Intercoms . . . . . .
. . . . . . . . . . . . . . 7
2.3.1 Full duplex intercom . . . . . . . . . . . . . . . . . . .
72.3.2 ClearCom type intercom systems . . . . . . . . . . . .
72.3.3 RTS TW Intercom . . . . . . . . . . . . . . . . . . . .
72.3.4 Matrix intercoms . . . . . . . . . . . . . . . . . . . . .
72.3.5 Wireless Intercom System . . . . . . . . . . . . . . . .
7
1 LAN (Local Area Network)
1.1 Definition of LAN
LAN can be defined as high speed data network. It covers a small
geographicnetwork. LAN can be used to connect several computers,
printers, computeraccessories, other devices etc. It helps many
users to access one device (sayone printer is used by many
computers). It also serves users to exchangefiles,emails etc.
1
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1.2 LAN access method
1.2 LAN access method
In a LAN there are many users. It is possible that two users may
want toaccess same device at a time. It will certainly create a
problem as the devicecan be accessed by one user at a time. Two
methods are used to preventthis.
1.2.1 Carrier sense multiple access collision detect
(CSMA/CD)
Here collision detect sensing is applied. It works as this:
suppose two usersare sending data at the same time. If a collision
occurs, it is sensed by oneuser. That user then waits for a random
while. Then he sends the dataagain. In most of the cases collision
will not occur again. It is because ofthe network connection. It is
customary that more the number of the users,more will be the number
of collisions. So if a LAN has many users, then itllcertainly
become slow.
1.2.2 Token passing
Here a token is passed from device to device. If a device wants
to send data,it has to wait for token to be received. The main
advantage of this methodis this that it is deterministic. It means
it is possible to calculate maximumtime it will take for a device
to send data.
1.3 Some other informations
In CSMA/CD we can have half duplex mode of communication. Here
oneuser can send a data but cannot listen to the network at the
same time. Ifhe wants to listen the network he must stop sending
the data. It is morelike a walkie-talkie. Only one person can talk
and other can only listen in aparticular time.
When switches are introduced, we can have full duplex mode of
operation.Here a user can send and receive data from the network
simultaneously. Itis like regular phones, where we can talk and
listen at the same time.
1.4 LAN Transmission Methods
There are three ways for this. They are,
2
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1.5 LAN Topologies
1.4.1 Unicast transmission
In this type of transmission one user communicates with another
user. It islike sending email to one person.
1.4.2 Multicast transmission
In this type, one user sends data to the network. It is then
copied and sentto many users. It is like sending emails to many
persons.
1.4.3 Broadcast transmission
In broadcast transmission, a persons data is sent to the network
and a lotof copies of it is made. After this it is sent to all the
users in that network.
1.5 LAN Topologies
LAN topologies is the manner in which network devices are
connected. Thereare four common LAN topologies. They are: bus,
ring, star, and tree.
1. BUS Topology: A bus topology is a connection scheme where all
thedevices are connected to a one common bus. All the necessary
data aresend to it firstly and then to other destinations.
Figure 1: Bus Topology
2. Ring Topology: In ring topology all the devices are connected
in se-ries to form a ring network. Here data can be sent in
unidirectionalmethod. If one computer wants to access another, it
got to go throughall other computers connected between them.
3. Star Topology: In star topology all the users are connected
to onecommon master. If any user wants to send data to other he has
to gothrough the master.
3
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1.6 LAN Devices
Figure 2: Ring Topology
4. Tree Topology: In tree topology, branches are formed. Here
hierar-chy levels are well defined.
1.6 LAN Devices
1. Repeater: A repeater is a device that is used to interconnect
twodevices. It is possible that wires used to connect two devices
may belong or of bad quality. It is expected that signals traveling
throughthem may be deteriorated. Repeaters are used to amplify,
restore thesignal to its original format.
2. Hub: A hub is a device that connects multiple user stations,
each bya dedicated cable. Electrical interconnections are made
inside the hub.Hubs are used to create a physical star network
while maintaining thelogical bus or ring topologies of the LAN.
3. LAN Extender: A LAN extender is used to connect to a more
broadnetwork. Its function is to sequence and filter data to be
sent.
4
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2. Intercom
Figure 3: Star Topology
Figure 4: Repeater
2 Intercom
2.1 General Information
Intercom is a private telecommunication system that allows
typically two ormore persons to communicate with each other like a
telephone. Two wired
5
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2.2 Some terms related to intercoms
Figure 5: LAN Extender
intercom system can be used as an intercom.
2.2 Some terms related to intercoms
Point-to-Point (P-P): Point-to-Point can be defined as one-way
com-munication between two intercom stations. Receiving station
mustpress a key to listen to sending station signal.
Party Line (PL): Party-line communication is a communication
be-tween two or more stations in full duplex mode. Each station has
toactivate the listen key to the desired party line to listen and
the talkkey to talk. Any station can be added and subtracted from a
party lineby activating talk and listen keys.
IFB: IFB means Interruptible Foldback. Here user is interrupted
byone audio source while listening another source.
IRF: IRF stands for Interrupted Return Feed. It is same as
IFB.
6
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2.3 Classification of Intercoms
Tally: Tally is a signal to indicate a particular purpose. The
ringingsound of a telephone is a tally.
2.3 Classification of Intercoms
There several types of intercoms. Some are,
2.3.1 Full duplex intercom
In a full duplex intercom system the users can communicate with
each otheron both directions without any specific control (like
pushing buttons as inwalkie-talkie.).
2.3.2 ClearCom type intercom systems
This type of intercom allows users to communicate in two
directions betweenanyone on the line on the basis that everyone
hears everything.
2.3.3 RTS TW Intercom
The TW (two wire) Intercom System is a two-wire conference- line
communi-cations system that allows up to 50 user stations to
connect across a commonline (also called a channel).
2.3.4 Matrix intercoms
A matrix intercom makes the user to have great power and
flexibility. Thisis largely because a matrix intercom consists of
cross-points that allow anyintercom input to be routed to any
intercom output.
2.3.5 Wireless Intercom System
It is a general intercom system that has wireless privilege.
7
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EEE 314
Electrical Services Design
Conduit Layout Lecture 1
Prepared by: Md. Itrat Bin Shams (Sanin)
-
Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 2
Symbols used in fittings and fixtures and in conduit layout:
Symbol Description Fittings and Fixture Conduit Layout
Wall Bracket Light at Lintel Level
2-Pin 5A Socket at SB Level
3-Pin 5A/15A Socket at Skirting Level
2-Pin 5A Socket at Table Height
3-Pin 5A Socket at Lintel Level
2-Pin 5A Socket at Skirting Level for TV
S
S
T
S
S
SL
TS
ST
15
L
SS
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 3
2-pin TV Antenna Socket
Same
Push Button
Same
Calling Bell or Buzzer
Same
Switch Board Concealed
Same
20A SP MCB At Skirting Level
Same
Fluorescent Wall Light Fitting
L
M
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 4
4-point Chandelier Light Fitting
Ceiling Light Fitting Type k
Same
Meter Board
Same
Distribution Board
Same
Exhaust Fan
Same
Ceiling Fan
F
K
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 5
Telephone Grommet
Same
Some Access Symbols: Symbol Conduit Layout Symbol
Concealed Conduit
Concealed Conduit Going Down
PVC Pipe Running through Floor
Miniature Circuit Breaker
Conduit Going up
-
Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 6
Example 1: Fittings and Fixtures layout:
A1
1
Switch Board Concealed
Wall Bracket Light at Lintel Level
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 7
Conduit Layout:
L
1
LWall Outlet at Lintel Level
C1
C1 = 2 X 1.5 mm2
SB 1
A 1
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 8
Example 2: Fittings and Fixture Layout:
A1 1
Switch Board Concealed
Wall Bracket Light at Lintel Level
A2
F1
Ceiling Fan
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 9
Conduit Layout:
L
1
L F
FCeiling Fan Outlet
Concealed Conduit
Conduit Going Down
SB 1
R
A 2
F 1
C1 C1
C3
A 1
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 10
Example 3: Fittings and Fixture Layout:
A1 1
Switch Board Concealed
Wall Bracket Light at Lintel Level
A2 F1
Ceiling Fan
ST1 C1
TV1
TS1
Two Pin TV Antenna Socket
Two Pin 5A Socket at Table Height
Two Pin 5A Socket at Skirting Level for TV
ST
TS
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 11
Conduit Layout:
L
1
L F
SB 1
R
L 3
F 1
C2 C1
C6
LT
S
S
T
Socket Outlet at Skirting Height
Socket Outlet at Table Height
ST TS 1 1
C1
C2 C1
A A C 1 2 1
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 12
Example 4: Fittings and Fixture Layout:
A11
A2 F1
C1 TV1
SS1
2A3
SS3
F2
Two Pin 5A Socket at SB Level
SS2
TS1
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 13
Conduit Layout:
L
1
L
S
S
S
S
L
2
F
L
F
C1
C3 C7
C2
C1
C2
C1 C1
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 14
Switch-Board Connection Diagram:
SB 1 SB 2
A A C F SS SS TS 1 2 1 1 1 2 1
A F SS 3 2 3
2 X 1.5 mm2
R R
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 15
Assignment:
A1
1
A2 F1
C1
TVSS1
2
SS3
F2
TS1
SS2
L2 L1
C2A3
C2
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 16
Practice Section: Draw Conduit Diagram for Example 1:
Draw Conduit Diagram for Example 2:
L
1
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 17
Draw Conduit Diagram for Example 3:
Draw Conduit Diagram for Example 4:
L
1
L F
L
1
L F
LT
S
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Prepared by: Md. Itrat Bin Shams (Sanin) Lecturer, EEE,
BUET.
EEE 314: Drawing Lecture 1 18
L
1
L
S
S
S
S