Transcript
Kochi Refinery
PRESENTATION ON SHUT DOWN IN BPCL- KOCHI
REFINERY
RAHUL . R . NAIR Trainee-BPCL-KR
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11 kV & 3.3 kV SWITCH GEAR
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1. There are many substations present in the plant area and also the amount of
Switch Gears and other electrical distribution are in large numbers.
2. Let us consider a 11kV and 3.3kV present in DHDS substation and its
electrical distribution system.
3. The panels are HT-2007 ( 11kV SWGR ) and HT-2008 ( 3.3kV SWGR ).
4. The supply to the 11kV SWGR is fed from Captive Power Plant ( CPP ) through
transformer and supply to 3.3kV SWGR is fed from 11kV SWGR through a step down
transformer rated 11kV / 3.3kV.
5. The step-down transformers are present in the substation yard.
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9. The 11kV and 3.3kV SWGR consists of two incomers ( 1 & 2 ) and a Bus Coupler .
10. The 11kV SWGR consists of transformer feeders and 3.3kV SWGR consists of HT
motor feeders.
11. These switch gears consists of mainly SF6 Circuit Breakers ( Sulphur Hexa-Fluride )
of 1250 A .
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The panel consists of the following components :-
1. POWER SWITCHING DEVICES
a) SF6 Circuit Breakers
b) SFU ( Switch Fuse Unit ) with contactor module
c) High Rupturing Capacity Fuse ( HRC )
d) Contactors
2. CONTROL DEVICES
a) Trip Selection
b) TNC Switch
c) Ammeter Switch
d) Test Terminal Block
e) Synchronizing Selector Switch
PANEL DETAILS
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3. INDICATIONS
a) Breaker On / Off
b) Auto Trip
c) Spring Charged
d) Ready to Close
e) Test / Service
f) Gas PR Low
4. METERING
a) Voltmeter
b) Ammeter
c) Watt Hour Meter
d) Power Factor Meter
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5. PROTECTION ( RELAYS )
a) Motor Protection
b) Sensitive Earth Fault
c) Over Current
d) Under Voltage
e) Check Synchronous
f) Master Trip
g) Inverse Definite Minimum Time O/C & E/F Protection
h) Line Potential Transformer
i) Bus Potential Transformer
6. AUXILIARY RELAYS
7. COMBIFLEX RELAYS
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8. INTERLOCKS
a) Door Interlocks
b) Mechanical Interlocks
9. BUS DUCT / BUS CHAMBER
10. BREAKER SLIDING CONTACTS
a) Control Cables
b) Inter-panel Wiring
11. CABLES
a) Motor Cables ( 3-core )
b) Feeders ( 3.5-core )
c) XLPE
d) PVC
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12. AUTO CHANGE-OVER SCHEME
13. CONTROL SUPPLY
14. SINGLE LINE DIAGRAM
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POWER SWITCHING DEVICES
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SF6 CIRCUIT BREAKERS
SF6 circuit breakers may use compressed air (puff) or the magnetic force of the arc itself to
elongate the arc. As the length of the sustainable arc is dependent on the available voltage, the
elongated arc will eventually exhaust itself. Alternatively, the contacts are rapidly swung into a
small sealed chamber. The escaping of the displaced air thus blowing out the arc.
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c)
The Isolator and Switch Fuse unit of Fuse Switch Unit are manually operated devices. A
Switch Fuse Unit or a Fuse Switch Unit also functions like the Switch, but can interrupt the
power supply by blowing the fuse in case the connected load draws excess current or when
a short circuit occurs.
SWITCH FUSE UNIT WITH CONTACTOR MODULE
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CONTROL MODULE
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a) In addition to providing a means to open and close the contacts manually, a
circuit breaker must automatically open its contacts when an overcurrent is sensed.
The trip unit is the part of the circuit breaker that determines when the contacts will
open automatically. The trip unit includes a trip mechanism that is held in place
by the trip bar. As long as the trip bar holds the trip mechanism, the mechanism
remains firmly locked in place. Trip flags off when a fault occurs ( over load ,short
circuit , under voltage etc).
TRIP
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b)
TNC Switch is a three position Switch. The switch are of two types : i) Having lockable Trip
position and other with ii) spring return to normal Neutral position. For manual operation this
switch is used to TRIP a breaker by moving it towards trip position and close by moving
it towards Close position.
In neutral position all the operations on AUTO mode or from remote can be done, as per the
scheme.
For keeping the breaker in OFF condition or for isolation, the switch can be kept in lockable
TRIP position, if that facility is available in the switch.
TNC SWITCH
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INDICATIONS
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a)
GREEN : Breaker Open & Mechanism charged
RED : Breaker Closed
AMBER : Trip/Trip Circuit Trouble
WHITE : Trip Circuit Healthy
ON / OFF INDICATIONS
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b) During auto trip the circuit breaker will not get ON without re-setting the fault or
any other cause for the trip. Once the trip is reset , the circuit breaker can be put on
to feed the load.
c) Spring is charged by providing a DC-voltage for the spring charging motor .The
control circuit requires DC voltage. This will charge the breakers within minutes .
Thus the charged spring stores potential energy which is used to operate quick
mechanisms( opening or closing of breaker contacts ).
AUTO TRIP & SPRING CHARGING
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d) This SPDT switch indicates that the circuit breaker is ready to close and
that the following conditions exist:
The circuit breaker is open
The stored energy mechanism is charged
The control unit is reset
The circuit breaker opening push button is neither locked nor
padlocked
The circuit breaker is in the fully connected or test position
The switch is field-installable.
READY TO CLOSE
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e) When the breaker is racked out completely for maintenance a test indication is
signalled on PMCC. At this point of time the breaker does not have any contact
with the bus bars.
When the breaker is racked in completely a service indication is signalled on
PMCC . This shows that the breaker is in service and ready to use.
TEST / SERVICE
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GAS PRESSURE LOW
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METERING
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a) A voltmeter is an instrument used for measuring electrical potential difference between two
points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to
the voltage of the circuit. Digital voltmeters give a numerical display of voltage by use of an
analog to digital converter.
VOLTMETER
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b) An ammeter is a measuring instrument used to measure the electric current in
a circuit. Electric currents are measured in amperes (A), hence the name. Instruments
used to measure smaller currents, in milli ampere or micro ampere range, are
designated as milli-ammeters or micro-ammeters.
AMMETER
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c) Watt hour meter is a device that measures and records over time the electric
power flowing through a circuit. Although there are several different types of watt- hour meters,
each consists essentially of a small electric motor and a counter. A precise fraction of the
current flowing in the circuit is diverted to operate the motor. The speed at which the motor
turns is proportional to the current in the circuit, and, therefore, each revolution of the
motor’s rotor corresponds to a given amount of current flowing through the circuit.
WATT-HOUR METER
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POWER FACTOR METER
A power factor meter is a kind of electrodynamometer, which is constructed with two
coils that are movable. These coils are set at 90 degrees to one another. One can
measure the power factor with the help of a power factor meter. The application of a
power factor meter is numerous like start up analysis of a motor or even detection of
hot spots.
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PROTECTION
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a) Motor Protection Relays are useful for protection of 3-phase AC induction
motors against various hazards. With their unique advantages they eliminate use of a
thermal / bimetal relay for motor protection. Being current sensing, they are to be selected
according to motor rating and are available for practically all ranges of motors. These relays
are ideally suitable for Air-conditioning Compressor motor protection, as also for motors in
machines, conveyors, cranes/hoists and lifts, and for pumps.
MOTOR PROTECTION RELAYS
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b) Sensitive Earth Fault Relay is a type of relay that is used to detect the presence
of an earth fault during the operation of an electrical device. Earth Fault occurs when
there is unbalancing of loads due to which the amount of current flowing through the
three phases ( R,Y,B ) will be in a different ratio.
SENSITIVE EARTH FAULT RELAY
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c) An Over Current Relay is a type of protective relay which operates when the
load current exceeds a preset value. The ANSI device number is 50 for an
instantaneous over current (IOC), 51 for a time over current (TOC). In a typical
application the overcurrent relay is connected to a current transformer and
calibrated to operate at or above a specific current level. When the relay
operates, one or more contacts will operate and energize to trip (open) a circuit
breaker
OVER CURRENT RELAY
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d) A relay that has contacts that operate when the voltage drops below a set
voltage is called Under Voltage Relays. Under voltage relays are used for protection
against voltage drops, to detect short-circuit faults, etc.
An undervoltage release triggers the breaker to open when the applied voltage falls
below a threshold. Often, an undervoltage release is operated from the system and
is intended to cause the breaker to open in the event something happens to cause
the system voltage to collapse.
UNDER VOLTAGE RELAYS
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e) Check Synchronising Relay : When closing a circuit breaker between two
energized parts of the power system, it is crucial to match voltages on both sides of the
circuit breaker before closing. If this matching or "synchronizing" process is not done
correctly, a power system disturbance will result and equipment can be damaged.
In order to synchronize properly, three different aspects of the voltage across the circuit
breaker must be closely monitored. The three aspects of the voltage are called the
synchronizing variables and are:
1. The voltage magnitudes
2. The frequency of the voltages
3. The phase angle difference between the voltages
CHECK SYNCHRONISING RELAY
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MASTER TRIP RELAY
Master Trip relays or Lockout relays are bipolar devices designed to operate when
voltage is applied. They are a link between protective relays and power circuit
controlling devices such as circuit breakers. Their purpose is to multiply the outputs of
protective relays or control relays so that one relay can trip and block closing of numerous
power circuit controlling devices.
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IDMTL O/C & E/F PROTECTION
IDMTL O/C & E/F PROTECTION is design to meet demand of low and medium
switchgear control. This type of relay is a 3 OC and 1 EF relay with Instantaneous high set
and programmable output to simplify feeder protection wiring. It continuously monitors all 3
phase and earth current, through CT connections. The high-speed micro-controller samples
this current through a 12-bit A/D converter. The micro- controller performs powerful Digital
Algorithms to find out Amplitude of current signal, and then this value is use for protection and
metering function. All measurement is tuned to fundamental frequency. Each input current is
also displayed on 16 x 2 LCD
display for metering. The Relay is having main three functions 1) Protection 2) Self-
Supervision 3) Measurement
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LINE POTENTIAL TRANSFORMER
Potential Transformer is designed for monitoring single-phase and three-phase
power line voltages in power metering applications. A Potential Transformer is a special
type of transformer that allows meters to take readings from electrical service connections
with higher voltage (potential) than the meter is normally capable of handling without at
potential transformer. Potential transformer models are available for metering AC
voltages from 120 volts AC to 36,500 Volts AC with burden ratings up to 500 VA.
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BUS POTENTIAL TRANSFORMER
It's a PT (potential transformer) that's attached to the bus. This depends
on the burden rating of the PT. If it's a 15VA PT, made for a secondary voltage of
120V, then the maximum secondary current should not exceed 0.125A.
Potential transformer is that which transforms one range of voltage (potential
difference ) to another range without changing frequency. Potential transformers are used to
(1) reduce the value of a high-voltage supply to a lower value (often 120 V) so that it may
be read by ordinary voltmeters, and (2) to electrically-isolate the voltmeter from the high-
voltage source for the purpose of safety.
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AUXILIARY RELAY
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Auxiliary Relay is relay which will repeat the operations of protective relays such
as tripping , time lag , breaking of trip circuit current , giving alarms , showing flags
etc. Protective relays contacts are light in weight and hence cannot carry large
amount of current for a long period. Therefore auxiliary relays, auxiliary switches and
repeat contacts are used to assist protective relays.
AUXILIARY RELAY
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BUS DUCT / BUS CHAMBER
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A bus duct is metal raceway that supports and contains a group of electrical
bus bars. The duct comes in standard 10 foot lengths.
One of the greatest advantages of bus ducts is that they are capable of
adding or removing a branch circuit without removing voltage from the whole duct.
BUS DUCT / BUS CHAMBER
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INTERLOCKING
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a) This lock prevents the compartment door from being opened when the circuit
breaker is in the connected position. If the circuit breaker is put into the "connected"
position with the door open, the door can be closed without disconnecting the circuit
breaker. The figure typically shows a door interlock pattern.
DOOR INTERLOCK
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b) mechanical interlocks
■ disconnecting when circuit breaker is closed
During any disconnecting attempt when the circuit breaker is closed, an interlocking
device ensures the tripping of the circuit breaker before the actual separation of the
main disconnects. The circuit breaker remains, however, operable in the other
positions: test, disconnected and withdrawn.
MECHANICAL INTERLOCKS
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■ circuit breaker closing when not completely connected
The interlocking device mentioned above prevents closing of the circuit breaker if the
connecting operation is not completely achieved.
■ connecting circuit breaker when door opened
VPEC and VPOC options prevent the compartment door from being opened when
the circuit breaker is in the connected position and from connecting the circuit
breaker when the door is open.
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BREAKER SLIDING CONTACTS
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a) Control Cables are a multistrand cable for transmission of information
on the state, location, or operating conditions of objects being controlled. It is used where
direct access to such objects is difficult or impossible. Control cables occupy an
intermediate position between power cables and communications cables. They are widely
used to connect electric instruments and apparatus, for secondary switching of remote-
control starters and regulators, for protective relaying, and in automation.
CONTROL CABLES
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b) Inter Panel Wiring is used for control equipment in control panel manufacture,
public buildings, control equipment, process control and automation, defence and
power network distribution.
INTER PANEL WIRING
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CABLES
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a) 3 Core Cables are manufactured for critical space requirement, protection
against rain-water and against ingress of small solid foreign bodies.
These Cables are produced from best quality electrolytic copper, which is
drawn, annealed on-life and bunched on automatic machines to ensure
flexibility and uniform resistance. The conductors are insulated with a
special grade of PVC on sophisticated co-extrusion lines.
MOTOR : 3 – CORE CABLES
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b) 3.5 core cables are generally used for lighting applications & in the applications
where the 0.5 core is used for neutral conductor because neutral conductor has
almost no - load to carry, thus saving the cost, by using half conductor size.
Neutral conductor is having half size in 3.5 core cable because neutral doesn't
have to carry the load current .This is either used for unbalanced current (in Y-
connection) or for earthing purpose which don't require high ampere rating.
FEEDER : 3.5 – CORE CABLES
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XLPE CABLES
Cross-linked polyethylene, commonly abbreviated PEX or XLPE, is a form
of polyethylene with cross-links. It is formed into tubing, and is used
predominantly in building services pipework systems, radiant heating and cooling
systems, domestic water piping, and insulation for high tension (high voltage)
electrical cables. XLPE-insulated cables have a rated maximum conductor
temperature of 90 °C and an emergency rating up to 140 °C, depending on the
standard used. They have a conductor short-circuit rating of 250 °C. XLPE has
excellent dielectric properties, making it useful for medium voltage—10 to 50 kV AC,
and high voltage cables—up to 380 kV AC- voltage.
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PVC CABLES
PVC is commonly used as the insulation on electrical cables; PVC used for this
purpose needs to be plasticized.
In a fire, PVC-coated wires can form hydrogen chloride fumes; the chlorine serves
to scavenge free radicals and is the source of the material's fire retardance. While
HCl fumes can also pose a health hazard in their own right, HCl dissolves in
moisture and breaks down onto surfaces, particularly in areas where the air is cool
enough to breathe, and is not available for inhalation. Frequently in applications where
smoke is a major hazard (notably in tunnels and communal areas) PVC-free cable
insulation is preferred, such as low smoke zero halogen (LSZH) insulation.
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AUTO CHANGE-OVER SCHEME
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AUTO CHANGEOVER SCHEME
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FLOW CHART
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CONTROL SUPPLY
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Control Supply to PMCC is 110 V dc and is fed from DCDB ( Direct Current
Distribution Board)
The DCDB is fed from battery charger in the substation.
The battery charger has a battery bank as back-up in case of supply failure to
the charger.
CONTROL SUPPLY
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SINGLE LINE DIAGRAM
11kV SWGR
3.3 kV SWGR
PMCC
MCC
11kV / 3.3kV 11kV / 3.3kV
Incomer-1Bus Coupler
Incomer-2
11kV / 0.433kV11kV / 0.433kV
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THANK YOU
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