CHAPTER 1 INTRODUCTION 1. 1 GENERAL Electrical faults seem to be the major reason for industrial disasters in the country as 56 per cent of incidents are reportedly caused by them. Overheating, ageing of the material and use of sub-standard quality of electrical gadgets have been the main factors contributing to the increasing electrical fire accidents in industries in the past four years. Electrical accidents continue to be a significant cause of on-the-job death in overall world. In our state also like this injuries happening frequently. On April 2013, we lost four workmen in Karur district due to this accident. Wiremen use for their security purpose like cheppals, wooden ladder, handglows etc,. This is not enough for their security. So we are introducing an innovative wiremen security system using fingerprint. One of the main job of wiremen security system is power automatically controlled by itself. The losses reduced by this method. It is an effective electrical safety intervention. Actual numbers of electrical injuries can indicate the overall magnitude of various electrical safety issues in the workplace. However, they are usually not [1]
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
CHAPTER 1
INTRODUCTION
1. 1 GENERAL
Electrical faults seem to be the major reason for industrial disasters in the
country as 56 per cent of incidents are reportedly caused by them. Overheating,
ageing of the material and use of sub-standard quality of electrical gadgets have
been the main factors contributing to the increasing electrical fire accidents in
industries in the past four years. Electrical accidents continue to be a significant
cause of on-the-job death in overall world. In our state also like this injuries
happening frequently. On April 2013, we lost four workmen in Karur district
due to this accident. Wiremen use for their security purpose like cheppals,
wooden ladder, handglows etc,. This is not enough for their security. So we are
introducing an innovative wiremen security system using fingerprint. One of the
main job of wiremen security system is power automatically controlled by
itself. The losses reduced by this method. It is an effective electrical safety
intervention. Actual numbers of electrical injuries can indicate the overall
magnitude of various electrical safety issues in the workplace. However, they
are usually not useful for comparing electrical injury experience among
different industries, or even from year to year in the same industry or group,
because of differences in employment. Rates of injurynormalize the data to
account for differences in exposedpopulations, and so afford a more direct
means to comparethe electrical safety history of disparate groups.
[1]
CHAPTER-2
LITERATURE SURVEY
2.1 Design of super conducting fault current controller
By the advent of the smart Grid and integration of distributed generators,
electrical networks are facing uncountable challenges. The existing protection
schemes that simply limit the fault current to the predetermined set values may
not perform optimally, and even the existing protection coordination schemes
fail and lead to catastrophic failures in the increasingly complex and
unpredictable grid operation. This paper proposes a novel and smart design of
fault current controller constituting a fullbridge thyristor rectifier embedding a
superconducting coil. When a fault occurs and the resulting current through the
superconducting coil exceeds a certain preset value based on the current
operating conditions of the grid to maintain the grid integrity, the magnitude of
the fault current is regulated to a desired value by automatic controlling of the
thyristor. This research also implements a lab-scale Smart FCC with smart
current control capability and demonstrates the desired functionality and
efficacy of design by changing the fault conditions. This proposed Smart FCC
design will make the Smart Power Grid capable of self-healing against current
faults.
2.2 Embedded Control System
The embedded control system consists of a target PC, a DAQ device, and
embedded software for the operation of the algorithm. The DAQ device is
connected to the target PC [11]. Therefore, the target PC can access the
acquired electrical signal through the DAQ device. In addition, the target PC
calculates the line impedance and phase angle according to the embedded
software algorithm.
[2]
In these short circuit tests, the amplitude of the input AC power voltage is 52 V,
and the target current is 60A. Then, the phase angle data table was calculated
to meet the target current condition using there positive circuit simulation.
2.3 Thyristor Control Circuit
To supply the gate pulse corresponding to the phase angle to the thyristor, a
control circuit is required. The circuit is composed of a phase control
IC(TCA785)[12], a BJT to amplify the pulse current, and some passive
elements. The control voltage that was calculated by the algorithm is provided
to the phase control IC. Then, the phase control IC outputs a gate pulse
corresponding to that control voltage. Fig.shows the circuit diagram of the
thyristor control circuit.
[3]
2.4 Superconducting Coil
To prevent adrastic increase in the fault current in the first halfcycle, a
large inductor is required in the FCC system. However, a large inductor
fabricated by the normal conductor leads to severe joule heating and avoltage
drop. To solve this problem, a superconducting coil that can prevent a sudden
increase in the fault current without joule heating loss is required. In this
research, a high temperature superconducting (HTS) coil has been employed of
unction’s large inductor. The superconducting coil consist of two pancake HTS
coils connected in parallel, and each pancake coil is wound with SuNAM
CCtapethatis4mmwide and that has a self field critical current of
about130A[13].The Fabricated Pancake coils are stacked together, and the
magnetic field generated by each coil is mutually linked. By doing this, the
total coil inductance can be treated as a single coil inductance even though the
two coils are connected in parallel. The inner radius of the pancake coil bobbin
is 54mm, and the number of turns is 50. The total inductance of the HTS coil
is about 0.1mH. Fig.4 shows the fabricated super conducting coil.
In this paper, Smart FCC employing a super conducting coil is proposed
which is an overland smart method for fault current control in Grid. The Smart
FCC can automatically detect a fault, calculate the line impedance, and
determine the proper phase angle. Through these processes, the Smart FCC can
control the fault current quickly and effectively. It is observed from the
experimental results that the fault current is reduced to the target value by
means of the phase angle calculated by the embedded control system.
[4]
2.5 Circuit Breaker Design and Operation to Improve Safety
Traditional “above- ground” applications of circuit breakers for over current
protection in industry are generally well understood. Defined design and test
standards, which vary some what across the globe, provide a frame work for
users of these devices to assure that the yare not misapplied. Attention to detail
in circuit breaker maintenance generally assures that these devices will operate
reliability and safety across the industry. However, when circuit breakers are
applied in underground mining applications, traditional design and test
standards give way to in-country mining safety authorities who typically dictate
requirements in these special applications. Because of this, ratings and test
requirements for low-voltage molded-case circuit breakers, low-voltage power
circuit breakers, medium-voltage vacuum and medium voltage sulphur hexa
fluoride(SF6) circuit breakers in underground mining are typically different.
In this environment, the user must be aware of issues specific to the application
to assure that these devices operate such that they assure miner safety and
operation reliability. This paper will discuss specific circuit breaker
applications in underground mining and recommend methods to maximize the
effectiveness of these protective devices in this environment.
[5]
2.6 Special circuit breaker applications for mining
Circuit breakers are used in underground mining equipment including the
machines used for mining itself, such as shears and continuous miners, and also
in power centers that typically feed electrical power to the underground mining
equipment. It is interesting that the circuit breaker components themselves are
not necessarily manufactured or tested to traditional standards that otherwise
apply for assemblies used in industry above ground. One variable is the
operating voltage of the device itself. Other issues around necessary fault
current ratings, operating conditions, circuit ground(earth)protection, and a
harsh environmental need to be considered.
. Low-voltage metal-enclosed control gear manufactured to IEC Standard 61439.
[6]
A typical power center applied in underground mining applications. The
power center assembly takes on several different forms and ratings dependent
upon where the underground mine resides across the world. The underground
power center is an engineered assembly designed to transform and distribute
electrical power brought to the underground from the surface. Typically, this
assembly includes a medium- voltage incoming circuit breaker or switch with
current-limiting fuse. This device protects a close-coupled dry- type vacuum
pressure impregnated power transformer used to convert the medium voltage to
a lower distribution voltage. The transformer then feeds low-voltage circuit
breakers that, in turn, feed and protect external underground mining loads
connected to the power center via extended trailing cables. These conductors
can often span thousands of feet(meters)in length.
The first not able difference in this assembly versus those
showninFigs.1and2 is the low-profile design. Where as the low-voltage metal-
enclosed ANSI/NEMA switch gear assemblies are typically2286mm(90in)
high and low-voltage metal- enclosed IEC control gear assemblies are typically
2000mm (78.75in) high, underground power centers are typically less than
half this height in order to satisfy clearance requirements in underground
mining applications. Because the application involves long lengths of
trailing cables, the issue of voltage drop on generally soft power systems
dictates that the application voltage is generally higher. In the U.S., it is not
unusual for secondary distribution voltages to be three-phase 1000 V ac, while
in China or Australia, for instance, operating voltages can be up to 1240 Vac.
Most importantly, the design codes and standards for this assembly are not
dictated by ANSI/NEMA or IEC standards. Instead, the in-country local
mining authority generally review sand approves these assemblies for
application in underground mines.
[7]
In the U.S., this authority is the U.S. government’s Mine Safety and
Health Administration(MSHA). MSHA dictates written regulations, and in the
event of a mining accident or fatality, they are the authority having jurisdiction
who will investigate the incident and issue other penalties by law. In Australia,
mines safety and inspection regulations are dictated by the Australian
government.
A.MCCBs in Mining
Today’s modern molded-case circuit breakers(MCCBs) are applied
throughout most, if not all, industries, offering a safe and economic means of
connecting and disconnecting loads from the electrical source and providing
both overload and short-circuit over current protection. Although there are
many types of MCCBs, all are comprised of five major components including
them olded case or frame, an operating mechanism, arc extinguishers, contacts,
and trip components. A cut away view of a typical MCCB is
showninFig.4hereinafter.
Unique issues exist in identifying when an MCCB should be considered as a
candidate to be replaced. By nature of the component itself, manufacturers of
these products assemble, calibrate, test, and, then, many times, seal the molded
cases of these devices. There are typically no internal serviceable parts, and
breaking the factory seal generally results in jeopardizing the manufacturer’s
warranty. Because of issues inherent to the product design, historically, the
maintenance of MCCBs by the end user has been limited to mechanical
mounting, electrical wiring, and manual operation of the mechanism. Although
beyond the scope of this paper, further information on the maintenance of
MCCBs can be found in[7].
[8]
CHAPTER 3
SYSTEM ANALYSIS
3.1 EXISTING SYSTEM
All linemen, especially those who deal with live electrical apparatus,
use personal protective equipment(PPE) as protection against inadvertent
contact. This includes rubber gloves, rubber sleeves, bucket liners and
protective blankets. When working with energized power lines, linemen must
use protection to eliminate any contact with the energized line.
The requirements for PPEs and associated permissible voltage depends
on applicable regulations in jurisdiction as well as company policy. Voltages
higher than those that can be worked using gloves are worked with special
sticks knows as hot-line tools or hot sticks, with which power lines can be
handled from a distance. Linemen must also wear special rubber insulating gear
when working with live wires to protect against any accidental contact with the
wire.
The buckets linemen sometimes work from are also insulated with fiber
glass. During the work these equipments if failure then accidents may happen.
These kind of resistors not provide proper security to our wiremen. If more
current generated from transformer these kind of existing system not enough to
secure them. In order to provide the security to the wireman at the workplace
we are introducing our concept to do make wellbeing.
[9]
3.2 DRAWBACKS
The flash injured an employee, damaged equipment and caused a
power outage affecting the surrounding area.
Lack of awareness and safety measures claimed the life of line
man. For example, In Nagpur, a 30-year-old woman who
was electrocuted while working with her husband at Navkanya
Nagar in Kalama on Sunday The couple was digging a well when
the incident took place.
Another example for electrocution is a lineman with the electricity
department, Krishna Madhu Velip,35,was electrocuted after
coming into contact with a live high tension wire at Costae ,Kalay,
on Tuesday morning. Velip was a resident of Barcem, Quepem.
These accidents are happened due to the usage of above mentioned
existing system.
[10]
3.3 PROPOSED SYSTEM
In order to provide the security to the wireman at the workplace we are
introducing our concept to do make wellbeing. To reduce the electrical injuries
we are introducing the Matrix keypad for providing security to wiremen. By
providing the 4-digit personal code for each wiremen we can control the power
supply. If the entered code is wrong then it will intimate to the lineman using
buzzer and also by the LCD.
We will place this control board on the transformer.After finishing their
work they must enter the personal code to the matrix keypad then power
supply is automatically ON. The control of this project is fully based on the PIC
microcontroller. This is main advantage of our project.
To Isolate controlling circuit from controlled circuit and to control high
voltage system with low voltage and then control high current system with low
current by using relay. Basically we are using EMR relay. The EMR relay act as
a switch to ON and OFF the current supply to transformer.
[11]
3.4 ADVANTAGES OF PROPOSED SYSTEM
The linemen no need to bring any safety equipments with themselves.
After providing the wireman secrete code to the keypad matrix the power
is automatically ON and OFF.
Here the loss of electrical injuries will be reduced.
It is more productive and secured method.
CHAPTER-4
[12]
SYSTEM SPECIFICATION
4.1 TOOLS USED:
• PIC Microcontroller-PIC 16F 887
• The ac input is 240V rms, 50Hz mains supply.
• LCD-2x16 LCD
• Matrix Keypad
• Relay- EMRs
4.2 BLOCK DIAGRAM:
4.3 CIRCUIT DIAGRAM
[13]
Matrix keypad
Power supply PIC Microcontroller 16F 887
LCD Display
Relay
Lamp 1 Lamp 2
[14]
4.4 PIC 16F887 MICROCONTROLLER:
High-Performance RISC CPU:
Only 35 Instructions to Learn:
All single-cycle instructions except branches
Operating Speed:
DC – 20 MHz oscillator/clock input
DC – 200 ns instruction cycle
Interrupt Capability
8-Level Deep Hardware Stack
Direct, Indirect and Relative Addressing modes
Special Microcontroller Features:
Precision Internal Oscillator:
Factory calibrated to ±1%
Software selectable frequency range of
8 MHz to 31 kHz
Software tunable
Two-Speed Start-up mode
Crystal fail detect for critical applications
Clock mode switching during operation for power savings
Power-Saving Sleep mode
Wide Operating Voltage Range (2.0V-5.5V)
Industrial and Extended Temperature Range
Power-on Reset (POR)
Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)
Brown-out Reset (BOR) with Software Control Option
[15]
Enhanced Low-Current Watchdog Timer (WDT) with On-Chip Oscillator
(software selectable nominal 268 seconds with full prescaler) with
software enable
Multiplexed Master Clear with Pull-up/Input Pin
Programmable Code Protection
High Endurance Flash/EEPROM Cell:
100,000 write Flash endurance
1,000,000 write EEPROM endurance
Flash/Data EEPROM retention: > 40 years
Program Memory Read/Write during run time
In-Circuit Debugger (on board)
Low-Power Features:
Standby Current:
50 nA @ 2.0V, typical
Operating Current:
11μA @ 32 kHz, 2.0V, typical
220μA @ 4 MHz, 2.0V, typical
Watchdog Timer Current:
1μA @ 2.0V, typical
4.5POWER SUPPLY SYSTEM
A power supply is a device that supplies electrical energy to one or more
electric loads. The term is most commonly applied to devices that convert one
form of electrical energy to another, though it may also refer to devices that
convert another form of energy (e.g., mechanical, chemical, solar) to electrical
energy. A regulated power supply is one that controls the output voltage or
current to a specific value; the controlled value is held nearly constant despite
variations in either load current or the voltage supplied by the power supply's
[16]
energy source. Every power supply must obtain the energy it supplies to its
load, as well as any energy it consumes while performing that task, from an
energy source. A power supply may be implemented as a discrete, stand-alone
device or as an integral device that is hardwired to its load. In the latter case, for
example, low voltage DC power supplies are commonly integrated with their
loads in devices such as computers and household electronics.
Mains input aspects
Usually, the ac input is 240V rms, 50Hz mains supply.
Take extra care when handling mains powered equipment, make sure of
your safety when constructing and testing.
PLUS make sure that adequate insulation and construction techniques are
employed in the unit.
Mains powered equipment must be properly protected by a fuse and
double pole power switch.
[17]
The mains powered equipment container (box) must be earthed if metallic
or double insulation techniques employed to provide input to output
isolation.
A lot of consumer electronic units (TV, DVD players and
the like) utilise double insulation techniques, so their mains
input power lead only contains Live and Neutral wires,
rather than also including an earth wire as well.
Double insulation techniques present at least two ‘high voltage’
insulation barriers between the mains input circuitry and the system being
powered. For example, the mains transformer has its primary (high
voltage) winding on one bobbin and its secondary winding an a separate
bobbin. Thus, if the primary winding burns up, the mains voltage cannot
reach the ‘secondary side’.
[18]
Transformer Rectifier Filter IC regulator Load
DESCRIPTION
The operation of power supply circuits built using filters, rectifiers, and then
voltage regulators. Starting with an ac voltage, a steady dc voltage is obtained
by rectifying the ac voltage, then filtering to a dc level, and finally, regulating to
obtain a desired fixed dc voltage. The regulation is usually obtained from an IC
voltage regulator unit, which takes a dc voltage and provides a somewhat lower
dc voltage, which remains the same even if the input dc voltage varies, or the
output load connected to the dc voltage changes.
A block diagram containing the parts of a typical power supply and the
voltage at various points in the unit is shown. The ac voltage, typically 120 V
rms, is connected to a transformer, which steps that ac voltage down to the level
for the desired dc output. A diode rectifier then provides a full-wave rectified
voltage that is initially filtered by a simple capacitor filter to produce a dc
voltage. This resulting dc voltage usually has some ripple or ac voltage
variation. A regulator circuit can use this dc input to provide a dc voltage that
not only has much less ripple voltage but also remains the same dc value even if
the input dc voltage varies somewhat, or the load connected to the output dc
voltage changes. This voltage regulation is usually obtained using one of a
number of popular voltage regulator IC units.
[19]
IN OUT 7805 GND
4.5.1 VOLTAGE REGULATORS
Voltage regulators comprise a class of widely used ICs. Regulator IC
units contain the circuitry for reference source, comparator amplifier, control
device, and overload protection all in a single IC. Although the internal
construction of the IC is somewhat different from that described for discrete
voltage regulator circuits, the external operation is much the same. IC units
provide regulation of either a fixed positive voltage, a fixed negative voltage, or
an adjustably set voltage.
A power supply can be built using a transformer connected to the ac
supply line to step the ac voltage to desired amplitude, then rectifying that ac
voltage, filtering with a capacitor and RC filter, if desired, and finally regulating
the dc voltage using an IC regulator. The regulators can be selected for
operation with load currents from hundreds of milli amperes to tens of amperes,
corresponding to power ratings from mill watts to tens of watts.
4.5.2 THREE-TERMINAL VOLTAGE REGULATORS:
FIXED VOLTAGE REGULATOR
Fig shows the basic connection of a three-terminal voltage regulator IC to
a load. The fixed voltage regulator has an unregulated dc input voltage, Vi,
applied to one input terminal, a regulated output dc voltage, Vo, from a second
terminal, with the third terminal connected to ground. For a selected regulator,
IC device specifications list a voltage range over which the input voltage can
vary to maintain a regulated output voltage over a range of load current.
[20]
The specifications also list the amount of output voltage change resulting
from a change in load current (load regulation) or in input voltage (line
regulation).
[21]
Primary Side
Usually single 240V winding or two 120V windings. Might have tappings to
allow operation from other supplies such as 200V, 220V, 240V, 100V, 110V
etc. These multi tapped transformers are usually fitted to test equipment that
could be used all over the world.
Secondary Side
Efficiency usually ~90% for small (<20VA) units, rising to 95% for larger
(~100 to 200VA) units.
MAINS transformers – ratings
Transformers are rated in VA – Volt Amps - with respect to their outputs
A 20VA transformer with a 10V secondary will provide 2A (10V x 2A =
20VA)
A 45VA transformer with a 15V secondary will provide 3A (15V x 3A =
45VA)
A 60VA transformer with two 20V secondary windings will provide 1.5A from
each secondary winding (20V x 1.5A x 2 = 60VA)
The power rating of a transformer is directly related to the cross sectional area
of its magnetic circuit – for a conventional E I transformer this is the cross
sectional area of its central limb (or twice the CSA of one side limb)
Rule of Thumb, VA rating = (CSA x 5.6)2 where CSA is measured in square
inches
So transformer with centre limb 1” wide and laminations 1.2” deep is rated to
(1” x 1.2” x 5.6)2 = 6.722 = 45VA
[22]
AC rectification
This full wave rectification arrangement only has one diode drop in the dc
path, but requires a centre tapped (or dual windings) secondary on the
transformer. More efficient on low voltage supplies because the diode drop
represents a significant loss at low voltage (despite additional transformer
losses). 2V drop (2 diodes) at 10V is 20% loss, whilst 1V drop (1 diode) at 10V
is 10% loss
The Smoothing Capacitor
The output from the transformer and rectifiers the sin waveform. The
smoothing capacitor ‘fills in’ the low voltage portions, so reducing the ripple
voltage amplitude. The larger the capacitor (for a given load), the smaller the
ripple voltage, but the higher the peak current through the rectifiers.
[23]
The Smoothing Capacitor
Close approximation calculations;
C x E = I x t where C is the capacitance in uF
E is the peak to peak ripple in Volts
I is the full load current in mA
t is the diode conduction time in ms, ~ 9ms @ 50Hz
With a 20Vrms output from the transformer the maximum voltage will be about
(20V x 1.414) less 2 diode drops, = 28.28V – 1.4V = 26.88V.
The minimum output (at full load) will be (28.28V x 0.9) – 2V = 23.4V
With a 4700uF smoothing capacitor the peak to peak ripple will be
(I x t)/C = (2000mA x 9ms)/4700uF = 3.83V this is the peak to peak ripple.
i.e. at full load the minimum voltage will be 23.4V – 3.83V = 19.5V.
[24]
4.6 LCD DISPLAY:
LCD is mainly used for display the information. Here we are using 2x16
LCD. Operation of the LCD is
The declining prices of LCDs.
The ability to display numbers, characters, and graphics. This is in
contrast to LEDs, which are limited to numbers and characters.
Incorporation of a refreshing controller into the LCD, thereby relieving
the CPU of the task of refreshing the LCD. In contrast, the LED must be
refreshed by the CPU to keep displaying the data.
Ease of programming for characters and graphics.
4.6.1 LCD pin descriptions
Vcc, Vss, and Vee:
While Vcc and Vss provide +5V and ground, respectively, Vee is used for
controlling LCD contrast.
RS, register select:
There are two very important registers inside the LCD. The RS pin is
used for their selection as follows. If RS=0 the instruction command code
register is selected, allowing the user to send a command such as clear display,
cursor at home, etc. if RS=1d the data register is selected, allowing the user to
send data to be displayed on the LCD.
[25]
R/W, read or write:
R/W input allows the user to write information to the LCD or read
information from it. R/W =1 when reading; R/W=0 when writing.
E, enable:
The enable pin is used b y the LCD to latch information presented to its
data pins. When data is supplied to data pins, high-to-low pulses must be
applied to this pin in order for the LCD to latch in the present at the data pins.
This pulse is a minimum of 450 ns wide.
D0 – D7:
The 8 bit data pins, d0 – d7, are used to send information to the LCD or
read the contents of the LCD’s internal registers.
A liquid crystal display (LCD) is a thin, flat electronic visual, 2*16
matrix display that uses the light modulating properties of liquid crystals (LCs).
LCDs do not emit light directly. Liquid crystal displays (LCDs) are a passive
display technology. This means they do not emit light; instead, they use the
ambient light in the environment. By manipulating this light, they display
images using very little power. This has made LCDs the preferred technology
whenever low power consumption and compact size are critical. They are used
in a wide range of applications, including computer monitors, television,
instrument panels, aircraft cockpit displays, signage, etc. They are common in
consumer devices such as video players, gaming devices, clocks, watches,
calculators, and telephones. LCDs have displaced cathode ray tube (CRT)
displays in most applications. They are usually more compact, lightweight,
portable, less expensive, more reliable, and easier on the eyes.
[26]
Pin Information of LCD:
4.6.2 Algorithm to send data to LCD:
1.Make R/W low
2.Make RS=0 ;if data byte is command RS=1 ;if data byte is data (ASCII value)