REPORT Of the electrical sub station equipments and all yards

1. TRAINING
(2018-2019)
SEMINAR REPORT
ON
220 KV GRID SUB STATION (R.V.P.N.),BUNDI (RAJ.)
SUBMITTED
IN
PRACTICAL TRAINING
FOR THE AWARD OF DIPLOMA IN
ELECTRONICS ENGINEERING
SUBMITTED BY –
Mohammed Sahil
2 YEAR Electronics

2. INDEX
1. Introduction
2. Grid Substation & Information
3. Single Line Diagram
4. Sub Station Equipment
5. Lightning Arrester (LA)
6. Potential Transformer (PT)
7. Capacitive Voltage Transformer (CVT)
8. Isolator
9. Bus Bars
10. Current Transformer (CT)
11. Circuit Breaker (CB)
12. Transformers
13. Wave Trap
14. Control Room
15. Capacitor Bank
16. Earthing System
17. Battery Bank
18. Power Line Carrier Communication (PLCC)
19. Feeders OR Yard

3. INTRODUCTION:
Rajasthan Vidyut Prasharan Nigam Ltd. is a company of Rajasthan State Electricity Board
(R.S.E.B.) stabilized by Govt. of Rajasthan.
An R.V.P.N. is to provide to reliable transmission service to customer.220 KV GSS, Bundi is a
part of R.V.P.N.
In 220 KV GSS, Bundi power comes from Kota Super Thermal Power Station (KSTPS).
220 KV GSS, Silore, Bundi is developed or construction in year of 2011 and being start in the
year of 2012.
There is one Executive Engineer (XEN.), ThreeAssistantEngineer (AEN.), Two Junior Engineer
(JEN.), Two EngineeringSupervisor (ES.) And Technical Staff.
The total staff of 220 KV GSS Bundi is members.
In GSS, there is a Yard, Control Room which is covered. The Area is about 52 Biga.their is a
Control Room, Transmission Sub Station. This is a outdoor type Sub Station .
The Whole supply of Bundi City, Talera, Silore, Namana by this GSS.
In this GSS electricity converted into 220 KV to 132 KV and 132 KV to 33 KV.
Sub Station is generally rated according to the voltage level of incoming line & the MVA
capacity of the Transformer.

4. GRID SUB STATION:
A substation is a part of an electrical generation, transmission,
and distribution system. Substations transform voltage from high to
low, or the reverse, or perform any of several other important
functions. Between the generating station and consumer, electric power
may flow through several substations at different voltage levels. A
substation may include transformers to change voltage levels between
high transmission voltages and lower distribution voltages, or at the
interconnection of two different transmission voltages.
Substations may be owned and operated by an electrical utility, or may
be owned by a large industrial or commercial customer. Generally
substations are unattended, relying on SCADA for remote supervision
and control.

5. The word substation comes from the days before the distribution
system became a grid. As central generation stations became larger,
smaller generating plants were converted to distribution stations,
receiving their energy supply from a larger plant instead of using their
own generators. The first substations were connected to only
one power station, where the generators were housed, and were
subsidiaries of that power station.
SELECTION OF A SITEOF A SUBSTATION:
1. SELECTION OF SITE:
A. Selection of site for construction of a Grid Sub Station is the
first and important activity. This needs meticulous planning,
fore-sight, skillful observation and handling so that the
selected site is technically, environment, economically and
socially optimal and is the best suited to the requirements.
B. The main points to be considered in the selection of site for
construction of a Grid Sub Station are given below.
C. The Site should be:
a. As near the load centre as possible.
b. As far as possible rectangular or square in shape for ease of
proper orientation of bus-bars and feeders.
c. Far away from obstructions, to permit easy and safe
approach/termination of high voltage overhead
transmission line.

6. d. Free from master/layouts or future development activities to
have free line corridors for the present and in future.
e. Easily accessible to the public road to facilitate transport of
material.
f. As far as possible near a town and away from municipal
dumping grounds, burial grounds, tanneries and other
obnoxious areas.
g. Preferably fairly leveled ground. This facilities reduction in
leveling expenditure.
h. Above highest Flood Level (HFL) so that there is no water
logging.
i. Sufficient, away from areas where police and military are
practice held.
D. The site should have as far as possible good drinking water
supply for the station staff.
E. The Site of the proposed Sub Station should not be in the
vicinity of aerodrome. The distance of a Sub Station from an
Aerodrome should be maintained as per regulations of the
Aerodrome authority. Approval in writing should be obtained
from the aerodrome authority in case the Sub Station is
proposed to be located near an aerodrome.
2. REQUIREMENT OF LAND/AREA:
The site should have sufficient area to properly accommodate the
Sub Station building, structures, equipments, etc. and should have

7. the sufficient area for future extension of the buildings and
switchyard.
The requirement of land for construction of Sub Station including
staff colony in as under.
S.NO. VOLTAGE CLASS
OF GSS
REQUIRED AREA
1. 400 KV 20.0 Hectare
2. 220 KV 6.0 Hectare
3. 132 KV 3.5 Hectare
While preparing proposals for acquisition of private land and
allotment of land for respective Grid Sub Stations shall be taken into
consideration as mentioned in Para 2.2 above. While selecting
Government land, the requirement may be made liberally but in other
cases, where payment is to be made for the land requirement should be
restricted the limit mention in 2.2.
TYPES OF SUBSTATION:
Depending upon the operating voltage, the Sub Station may be
classified:
1. Outdoor
2. Indoor
3. Pole Mounted
In Outdoor Sub Station all equipment lies in open air clearances that
may be required between high voltage terminals and equipment. This is

8. the reason that the for 132KV and above, Outdoor Sub Stations are
recommended.
This is the diagram of an outdoor Substation system:
1. Power lines
2. Ground Wire
3. Overhead Wire
4. Transformer for Measured volts (PT)
5. Isolator (Disconnect Switch)
6. Circuit Breaker (SF6 CB)
7. Current Transformer (CT)
8. Lightning Arrester
9. Main Transformer ( Auto)
10. Control Building
11. Power line
The High Voltage Equipment should be able to with stand worst
wheaten condition.

9. Sub Station Equipments:
Most common equipments found in a GSS:
1. Transformers
2. Circuit Breakers (CB)
3. Isolators
4. Current transformers (CT)
5. Potential transformers (PT)/ Capacitive
Voltage transformers (CVT)
6. Bus bars (BB)
7. Lightning arrestors (LA)
8. Wave trap (for PLCC communication)
9. Overhead earth wire
10. Underground Earthing system
11. Control Panel
12. Power Line Carrier Communication (PLCC)

10. LIGHTHING ARRESTER/ SURGE ARRESTER:
These are devices made for the protection of a power system arising
from dangerous surges. These surges (high voltage impulses of shorter
duration) are either from lightning or load switching.
A surge arrester is a device to protect electrical equipment from over-
voltage transients caused by external (lightning) or internal (switching)
events. Also called a surge protection device (SPD) or transient voltage
surge suppressor (TVSS), this class of device is used to protect
equipment in power transmission and distribution systems. (For
consumer equipment protection, different products called surge
protectors are used.) The energy criterion for various insulation
materials can be compared by impulse ratio. A surge arrester should
have a low impulse ratio, so that a surge incident on the surge arrester
may be bypassed to the ground instead of passing through the
apparatus.

12. Potential transformers:
Potential Transformers are instrument transformers. They have a large
number of secondary turns and a few numbers of primary turns. They
are used to increase the range of voltmeters in electrical Substation and
generating Station. These are also called as voltage transformers used
for line circuit protection.
Potential Transformers Step- Down the systems voltage to a low value.
The Rated Secondary Voltage of a PT is generally 100/110/120 Volt.
These Step down voltages are used for measurement of voltages,
active, reactive, and apparent power, power factor frequency.
The Relay which detect t abnormal conditions by monitoring system
voltages are supplied from the output of PT.

13. Capacitive Voltage Transformer (CVT):
The CVT comprises of a capacitor voltage divider with a potential
transformer connected to the relative lower output voltage of the
capacitive divider. This unit is so designed that secondary voltage of the
PT is substantially proportional to end in phase with the incoming
voltage applied to the capacitor divider unit.
For measurement of voltage at the High Tension Side of a Sun-
Transmission Sub- Station Capacitor Voltage Transformer (CVT) are
used.

14. ISOLATER:
These are mechanical devices used to open an electrical path. This is
particularly vital as a visual indication of isolating high voltage
components, which is not provided by a CB.
Isolators are designed to open a circuit under no load. Its main purpose
is to isolate portion of ckt from the other & is not intended to be opened
while current is flowing in the line.
There are two types;
1. Off Load Isolators
2. On load Isolators

15. It isolates the devices from live line when there is maintenance. It
operates when there is no load. It is also used to change bus bar line
from main to reserve or vice-verse.
Manual or Motor operated disconnect switches should be provide for
isolating all circuit breaker for maintenance and repair. Isolators are
also used for disconnecting lines and allow the equipment to be taken
out of the system for repair, maintenance and testing, Isolators help to
have a sect ionized bus system. Isolators are not supposed to be opened
under loaded conditions and for this reason, are interlocked with
circuit breaker to prevent operation on load. However, these are
capable of dealing with small charging current. Isolators on the line
side of the line circuit breaker should be equipped with ground blade.

16. BUSBARS:
These are normally made of hollow Copper/Aluminum rods. The
reason is to account for the high current flow so that normal cables
would be unable to withstand the electrical stress produced.
The term “bus” is derived from the word omnibus which means a
collector of things. Bus, therefore, refer to the main collectors of
electrical energy.
An electric bus collects electric energy at one location and the bus bar
is the conductor through which the electric current flows. The material
normally used for bus bars are copper and aluminums.
The Three Buses in a three phase system may be mounted horizontally
or vertically.

17. Bur bar may be of outdoor type when situated in open space or of
indoor type when used inside a building. Outdoor Bus Bars are
generally mounted horizontally insulated from earth by post insulators
made of Porcelain.
Outdoor Buses are Widely Spaced to prevent birds with a large wing
spread causing short circuit of the buses. Indoor Buses may be open or
enclosed.
In a Substation, there will be three bus-bars where the three incoming
lines are connected. The high-tension side terminals of the step-down
transformer are connected to these bus bars. The low voltage side
terminals are connected to the set of Bus-Bar which is connected to the
outgoing line.
When very high short-circuit currents flow through the bus bars, the
mechanical force acting between conducting buses parallel to each

18. other may increase enormous. The force is directly proportional to
square of currents and adversely proportional to spacing between
conductors. This force tends to pull the buses together or force than a
part depending upon the direction of currents in buses. The space
therefore is to be kept wide to reduce this force.
In 220 KV GSS Three buses systems are present:
1. Main Bus-1
2. Main Bus-2
3. Auxiliary Bus

19. CURRENT TRANSFORMERS:
A current transformer (CT) is a type of transformerthat is used to
measurealternatingcurrent(AC). It produces a current in its secondary
which is proportionaltothe currentin its primary. Current transformers,
along with voltageor potentialtransformersare instrumenttransformers.
Instrument transformers scalethelargevalues of voltageor currenttoo
small, standardized values that areeasy to handlefor instruments
and protectiverelays. The instrumenttransformersisolatemeasurement or
protection circuits fromthehigh voltageof the primary system. A current
transformer provides a secondary current thatis accurately proportionalto
thecurrent flowing in its primary. Thecurrenttransformer presents a
negligibleload to the primary circuit. Currenttransformers arethe
current-sensingunitsof the power system and are used at generating
stations, electricalsubstations, and in industrialand commercialelectric
power distribution.
4. A type of transformer used toreducethemagnitudeof the
flowing current in a conductor,so that currentcan behandled safely for
measurement & instrumentation. Primary sideis the currentmeasured
and secondary side will have the reduced current. Reductionin magnitude
will be determined by the turn’s ratio
5.
6.
7.
8.
9.

21. CircuitBreakers:
These are normally classifiedaccording to the arc-quenching
medium around the contacts:
1. Air circuit breakers; Air Blast circuit breakers (ACB)
2. Oil circuit breakers (OCB)
3. Vacuum circuit breakers (VCB)
4. Gas circuit breakers (e.g.: SF6 breakers)
Vacuum circuit breakers (VCB):A circuit breaker is a device
used to complete, maintain, and interrupt currents flowing in a
circuit under normal or faulted conditions. A vacuum circuit
breaker utilizes a vacuum to extinguish arcing when the
circuit breaker is opened and to act as a dielectric to insulate
the contacts after the arc is interrupted. One type of circuit
breaker is called a reclose. A vacuum reclose is designed to
interrupt and reclose an AC current circuit automatically, and
can be designed to cycle a set number of times before it must be
reset manually.

22. SF6 Circuit Breaker: operate to switch electric circuits and
equipment in and out of the system. These circuit breakers are
filled with compressed sulfur-hexafluoride gas which acts to
open and close the switch contacts. The gas also interrupts the
current flow when the contacts are open
.

23. TRANSFORMERS:
“TRANSFORMER”- one of oldest innovations in Electrical Engineering. A
Transformer is an electrical device that can be used to transfer the
power from one circuit and another circuit without physical contact
and without changing its characteristics like frequency, phase. It is an
essential device in every electrical network circuitry. It consist majorly
two circuits, namely primary circuit and one or more secondary
circuit.
The step down transformer may be three- phase or single phase unit
depending on the size and choice.
Tap changing transformer are preferred. Star-delta or delta-star
connection is used. If star-star connection is used, then a delta
connected tertiary winding may be necessary to suppress harmonic
voltage.
Generally, More than one transformer will be used for better reliability.
The total MVA capacity of this transformer is the MVA rating of the
Sub Station.
In 220 KV GSS, Silore, Bundi 3 Power Transformer is used. All
transformers are step down.
POWER TRANSFORMERS:
When classified depending on the voltage levels in both sides of a
transformer:
1. step-uptype (used in voltage increase from alternator->
transmission line.

24. 2. Step-downtype (used in voltage decrease from transmission line-
>distribution)
MAIN PART OF POWER TRANSFORMER:
A. Conservator Tank
B. Winding (H.V winding,L.V winding, Tertiary winding)
C. Tap Changer
D. Core
E. Buchholz relay
F. Air Cell
G. Dehydrating Breather
H.indicators (Temp. of H.V, L.V winding and Oil).
AUTO TRANSFORMERS:
Autotransformers are frequently used in power applications to
interconnect systems operating at different voltage classes, for
example 400 kV to 220 kV for transmission. They are also often
used for providing conversions between the two common domestic
main voltage bands in the world (400, 200, 66 kV). The links
between the UK 400 kV and 275 kV `SuperGrid` networks are
normally three-phase autotransformers with taps at the common
neutral end. Autotransformers are built with common main winding
and a separate low voltage winding. Autotransformers are often
used to step up or step down voltages in the 110-115-120 V range
and voltages in the 220-230-240 V range - for example, providing
110 V or 120 V (with taps) from 230 V input, allowing equipment

25. designed for 100 or 120 V to be used with a 230 V supply. This
allows US electrical equipment to be fed from the higher European
voltage. Autotransformers can also be used to supply European 230
V appliances from a 100 or 120 V supply in countries outside
Europe. In all cases the supply and the autotransformer must be
correctly rated to supply the required power.
POINTS-
 In Transformer Cooling System are Used. Air Natural / Oil Natural.
 Radiator is use for the Cooling Arrangement.
 The oil is filling in the conservator tank.
 Dehydrating Breather use for absorb the moisture in the
transformer. Connected with conservator tank.
Buchholz Relay:
Buchholz Relay is a gas actuated relay. It can be fitted to be
Transformer equipped with conservator tanks as it is installed in
between the conservator tank and the main tank i.e., the pipe was
connected.
PRINCIPLE: Whenever a fault occurs inside the transformers, the oil of
the tank gets overheated and gases are generated. The heat generated
by the high local current causes the transformer oil to decompose and
produce gas which can be used to detect the faults.
OPERATION: When a fault occurs, heat is produced due to current
leakage, some of the oil in the transformer tank evaporates and some
vapors collect in the top of the chamber while passing to conservator

26. tank. When a predetermined amount of vapors accumulate in the top
of the chamber, the oil level falls, and so closes the alarm circuit f the
relay and rings the bell. Thereby the operator knows that there is some
fault occurred in the transformer.

27. ]

28. ]

29. WAVE TRAP:

30. This is used for exchange of data and transfer of message between
sending ends to receiving end of substation, voice communication is
necessary for this purpose high frequency carrier currents transmitted.
Hence, this communication is called as owner line carrier
communication.
For exchange of data and transfer of data and transfer of messages
between substation, voice communication is necessary. For this purpose
high frequency carrier current is transmitted over same transmission
line on which power is transmitted. Hence, this communication is
called as power line carrier communication.
Wave trap is connected only two phases R&Y phase and B&Y.
CONTROL ROOM:
The control room of a sub-station house:

31. 1. Instrument Panels.
2. Various types of relays.
3. Battery bank & Charging Controller.
4. Supervisory control apparatus.
5. Telephone System.
Protective relay are classified according to their function, and there are
a wide variety of protective relays available.
The over current, for e.g., monitors current and operates when the
current magnitude exceeds a present value. Other types of protective
relays provide protection for other abnormal fault condition. The relay
receives input from the instrument transformer and therefore, low-
current, low-voltage devices. The relay is placed on a control panel on
which a single line diagram of the layout of the substation is shown.
Electrical & Electronics instruments like ammeter, voltmeter, wattmeter,
varmeter, energy meter, frequency meter and power factor meter are
located in the control room.
In Control Room Two Types of panels are there:
A.Simplex Panels: are those panels in which the only one side active
that means the relay and meters are at a same side. Maximum panels
are this type.
B.Duplex Panels: are those panels in which the both side active that
means the relay and Meters are at a different side.

32. In 220 KV GSS both types of panels are present there.
The control panel are control the all equipment of yard. The control
panel gives the information about the fault and tripping. the control
panel consist the separate panels for each feeders.
The Panels consist the below equipment:
1. Semaphore Switch
2. Trip control Switch
3. Reading Meters
4. Master 86 Relays
5. over Current and Earth Fault Relay
6. Directional over Current and Earth Fault Relay
7. Induction disc and fuse failure relay
8. Differtial Earth Fault Relay
9. Indication Lamp
In 220 KV GSS Silore, Bundi the total control panels are present.
CAPACITOR BANK:
Electric Power Tool: Substation Equipment - Capacitor
Bank. Capacitors are used to control the level of the
voltage supplied to the customer by reducing or

33. eliminating the voltage drop in the system caused by
inductive reactive loads.
EARTHINGSYSTEM:
It is connected between the conductor and earth. Normally, is in open
position. However, when the line is disconnected, this switch is closed
to discharge trapped charge to ground.
Earthing is the most important part in the Grid Substations..

34. In other words Earthing means connect ion of electric equipment to the
earth with the help of connecting Rods or Wires of Neugable Resistance
is known as Earthing.
Type of Earthing on 220 KV Grid Sub Station:
1. Pipe Type Earthing
2. Plate Type Earthing
POWER BANK:
In RSEB almost on all the 220 kV Sub-stations two sets of 220 V (for
protection) and one set of 48 V (for carrier communication) lead Acid
station batteries along with battery chargers are installed. The battery
charging equipments comprises of a float charger and a boost
charger. Stabilization output voltage is provided in the float charger

35. to float the battery at the correct level. The battery can be boost
charging after a prolonged mains failure by the boost charger. These
chargers have been provided protection for under voltage DC & earth
fault. DC Board is installed to feed various essential DC load from a
separate feeder.Recommended specific gravity of cells at 270
C
(electrolyte temp) should be 1.210 ± 0.005. Actual temp should be
measured in the electrolyte of the cell. If the temp is different than
270
C the correction ± 0.0007/0
C change in temp. should be made in
sp. gr. (Subtract for temp. below 270
C and add for temp. above
270
C).
Voltage of each cell (float charger in 'ON' position) should be.2.16-2.2
volts.
Volt across 55 cell (110 V) should be maintained between 118.8-121
volts.
Volt across 24 cells (48 V) should be maintained between 51.8-52.8
volts.
Top up cells to the correct level (red mark of float indicator of cell)
with pure distilled water only.
Check for corrosion of connectors and if present remove with fresh
water pure distilled water only.
Check for any lose connection, wipe out old petroleum jelly and apply
new jelly.

36. Carry out boost charging of battery when the sp gr. falls below 1.200,
charging current 10% of the AH capacity and on free gassing reduce
current to 50% of the charging current till :-
The voltage has reached maximum and steady for 3 hours and sp.gr.
of electrolyte in the pilot cells has also reached maximum and is
steady for 3 hours. All the cell should gas freely. Any cell failing to gas
freely or having sp.gr. lower than 1.140 or having gravity more than
1..230 should be attended immediately. Remove defective cells and
charge on a separate charger (Milky booster). Put it in the circuit if
sp.gr. is maintained Temp. during boost charging should not exceed
450
c, if rises, reduce the charging current.
When different sp.gr. is noticed in different cells equalising charge
should be given to the entire battery i.e. boost charge battery for 2-3
hours. If sp.gr. is not maintained repeat process after fifteen days.
Even if the sp.gr. is normal, equilising charge should be given to the
battery once in a month i.e. Boost charge battery for 2-3 hours at
current 10% of AH capacity.
After service of 5 years the entire cells of the battery should be
discharged completely and recharged to ascertain battery life.
On fully Charged battery sp.gr. adjustment can be done in
consultation with firm if found less, by putting higher specific gravity
acid (1400 so,gr,).

37. POWER LINE CARRIERCOMMUNICATION
(PLCC):

38. GENERAL INFORMATION:
PL 9500 (Ver.-01) is a few generation Power line Carrier
Communication (PLCC) equipment intended for
transmission of speech,facsimile,telegraphy,telemetry (
RTU data)
And Tele-protection signals. It employs the carrier
frequency range of 32 KHz to 508 KHz over High
Voltage overheadpower transmission lines with suitable
line coupling equipment. Because of their low
attenuation in this carrier frequency range the
transmission line are good means of communicating

39. information over medium to long distances. The overall
cost of the PLCC equipment is relatively low distance
communications.
The equipment employs Amplitude Modulation Single
Side Band Suppressed Carrier (AM-SSB-SC) transmission
to permit longer range of transmission by optimum
utilization of transmitted power and frequency
spectrum.
The equipment offers a Single Channel expandable to
two channels. Both the channels can be configured for
full bandwidth speech / fax conversation or shared
speech-cum-superimposed data channel or one high-
speed 4 Wire Exclusive data channel of1200 baud. The
equipment is also suitable for transmission of
teleportation signals.
The terminal employs DSP techniques for full field
programmability and is true flexible, Easy to use and

40. compact. Leading to simplified network design,
installation and maintenance.
The equipment compels to the relevant ITU-T/CCITT, IEC
495: 1993-2009 and IS 9482:1996-2001
Specification: Ensuring reliable Coupling of Channels at
to VF interfaces in power system Control Centre, Power
Stations, Microwave Radio and Leased Backup links.
Systems have been duly provided. Once commissioned,
the system can be verified for operation through user-
friendly LCD screens and Keypad.

41. FEATURES:
 Single or dual ChannelConfigurations.
 Terminal, Drop / Insert through coupled repeaters.
 32 KHz to 508 KHz frequency range with 1 KHz
frequency allocation.
 Power Amplifiers available for 20/40/80WPEEP
power output.
 300 Hz to 3720 Hz Audio Frequency Band.
Digital Signal processing technique for easy field
programmability.
 Channel frequencies, transmission filters, line
impedance and speech, data and protection coupler
levels.

42.  Remote extension of direct EPBAX line, Hot line,
Express Channel and 2- Wire E&M Modes Available
for interface unit.
 Same Channel Modem for speech,fax&high speed
RTU Data
 Local and Remote loopback facility.
 Fully complies with IEC 495: 1993-2009 And IS
9482: 1996-2001 Standard.
 Supervisory unit facilitates easy maintenance and
operation.
 Easy User Interface using LCD display for status and
alarm monitoring.
FEEDERS:
220 KV YARDS:

43. 132 KV YARDS:

44. 33 KV YARD: