INDUSTRIAL TRAINING

2013

NTPC LIMITED

BADARPUR THERMAL POWER STATION

MADE BY :

Jatan Singh Soni

11BEE0061

Training at BTPS

I was appointed to do 4 week training at this esteemed

organization from 3rd June to 4th July, 2013. I was

assigned to visit various divisions of the plant, which

were:

Electrical Maintenance Department I (EMD-I)

Electrical Maintenance Department II (EMD-II)

Control and Instrumentation Department (C&I)

It was really amazing to see the power plant and learn

how electricity, which is one of our daily requirements of

life, is produced.

INDEX

• OPERATION OF POWER PLANT

• PARTS OF A POWER PLANT

• VARIOUS CYCLES AT POWER STATION

• ELECTRICAL MAINTENANCE DEPARTMENT-I

• ELECTRICAL MAINETNANCE DEPARTMENT-II

• CONTROL AND INSTRUMENTATION

The basic steps in the generation

of electricity from coal involves

following steps:

• Coal to steam – Steam Generator

or Boiler

• Steam to mechanical power -

Steam Turbine

• Mechanical power to electrical

power – Electric Generator

BASIC POWER PLANT CYCLE

PARTS OF A POWER

PLANT1. Cooling tower

2. Cooling water pump

3. Transmission line (3-phase)

4. Unit transformer (3-phase)

5. Electric generator (3-phase)

6. Low pressure turbine

7. Condensate extraction pump

8. Condenser

9. Intermediate pressure turbine

10. Steam governor valve

11. High pressure turbine

12. Deaerator

13. Feed heater

14. Coal conveyor

15. Coal hopper

16. Pulverized fuel mill

17. Boiler drum

18. Ash hopper

19. Super heater

20. Forced draught fan

21. Reheater

22. Air intake

23. Economizer

24. Air preheater

25. Precipitator

26. Induced draught fan

27. Flue Gas

THE EQUIPMENTS THAT NORMALLY FALL IN

THIS CATEGORY ARE:-ISOLATOR

• Isolator cannot operate unless breaker is open

• Bus 1 and bus 2 isolators cannot be closed simultaneously

• The interlock can be bypass in the event of closing of bus coupler breaker.

• No isolator can operate when the corresponding earth switch is on

SWITCHING ISOLATOR

• Switching isolator is capable of:

• Interrupting charging current

• Interrupting transformer magnetizing current

• Load transformer switching. Its main application is in connection with the transformer feeder as the unit

makes it possible to switch gear one transformer while the other is still on load.

CIRCUIT BREAKER

• One which can make or break the circuit on load and even on faults is referred to as circuit breakers. This

equipment is the most important and is heavy duty equipment mainly utilized for protection of various

circuits and operations on load. Normally circuit breakers installed are accompanied by isolators.

LOAD BREAK SWITCHES

• These are those interrupting devices which can make or break circuits. These are normally on same

circuit, which are backed by circuit breakers

EARTH SWITCHES

• Devices which are used normally to earth a particular system, to avoid any accident happening due to

induction on account of live adjoining circuits. These equipments do not handle any appreciable current

at all. Apart from this equipment there are a number of relays etc. which are used in switchgear.

OIL CIRCUIT

BREAKERS

AIR CIRCUIT

BREAKERS

SF6

CIRCUIT

BREAKERS

RATINGS OF THE GENERATORS USED

• Turbo generator 100MW

• TURBO GENERATOR 210 MW

•• The 100 MW generator generates 10.75 KV and

210 MW generates 15.75 KV. The voltage is

stepped up to 220 KV with the help of generator

transformer and is connected to the grid.

• The voltage is stepped down to 6.6 KV with the

help of UNIT AUXILLARY TRANSFORMER (UAT)

and this voltage is used to drive the HT motors.

The voltage is further stepped down to 415 V and

then to 220 V and this voltage is used to drive Lt

Motors.

COOLING OF TRANSFORMERS

OF LARGE MVAAs size of transformer becomes large, the rate of the oil circulating becomes insufficient to dissipate

all the heat produced & artificial means of increasing the circulation by electric pumps. In very large

transformers, special coolers with water circulation may have to be employed.

TYPES OF COOLING:

Air cooling

Air Natural (AN)

Air Forced (AF)

Oil immersed cooling

Oil Natural Air Natural (ONAN)

Oil Natural Air Forced (ONAF)

Oil Forced Air Natural (OFAN)

Oil Forced Air Forced (OFAF)

Oil immersed Water cooling

Oil Natural Water Forced (ONWF)

Oil Forced Water Forced (OFWF)

UNIT AUXILIARY TRANSFORMER (UAT)

Unit I & V- 12.5 MVA

The UAT draws its input from the main bus-ducts. The total KVA capacity

of UAT required can be determined by assuming 0.85 power factor & 90%

efficiency for total auxiliary motor load. It is safe & desirable to provide

about 20% excess capacity then circulated to provide for miscellaneous

auxiliaries & possible increase in auxiliary.

STATION TRANSFORMER

It is required to feed power to the auxiliaries during startups. This

transformer is normally rated for initial auxiliary load requirements of the

unit in typical cases; this load is of the order of 60% of the load at full

generating capacity. It is provided with on load tap change to cater to the

fluctuating voltage of the grid.

NEUTRAL GROUNDED TRANSFORMER

This transformer is connected with supply coming out of UAT in stage-2.

This is used to ground the excess voltage if occurs in the secondary of

UAT in spite of rated voltage.

BUS BAR

Bus bars generally are of high conductive aluminum conforming to IS-5082 or copper

of adequate cross section. Bus bar located in air insulated enclosures & segregated from all

other components .Bus bar is preferably cover with polyurethane.

BY PASS BUS

This bus is a backup bus which comes handy when any of the buses become faulty. When any

operation bus has fault, this bus is brought into circuit and then faulty line is removed there

by restoring healthy power line.

LIGHTENING ARRESTOR

It saves the transformer and reactor from over voltage and over currents. It grounds the

overload if there is fault on the line and it prevents the generator transformer.

WAVE TRAP

WAVETRAP is connected in series with the power (transmission) line. It blocks the high

frequency carrier waves (24 KHz to 500 KHz) and let power waves (50 Hz - 60 Hz) to pass-

through.

BREAKER

Circuit breaker is an arrangement by which we can break the circuit or flow of current. A

circuit breaker in station serves the same purpose as switch but it has many added and

complex features. The basic construction of any circuit breaker requires the separation of

contact in an insulating fluid that servers two functions:

• extinguishes the arc drawn between the contacts when circuit breaker opens.

• It provides adequate insulation between the contacts and from each contact to earth.

EARTHING ROD

Normally un-galvanized mild steel flats are used for earthling. Separate earthing electrodes are

provided to earth the lightening arrestor whereas the other equipments are earthed by connecting

their earth leads to the rid/ser of the ground mar.

CURRENT TRANSFORMER

It is essentially a step up transformer which step down the current to a known ratio. It is a type of

instrument transformer designed to provide a current in its secondary winding proportional to the

alternating current flowing in its primary.

POTENTIAL TRANSFORMER

It is essentially a step down transformer and it step downs the voltage to a known ratio.

RELAYS

Relay is a sensing device that makes your circuit ON or OFF. They detect the abnormal conditions in

the electrical circuits by continuously measuring the electrical quantities, which are different under

normal and faulty conditions, like current, voltage frequency. Having detected the fault the relay

operates to complete the trip circuit, which results in the opening of the circuit breakers

and disconnect the faulty circuit.

There are different types of relays:

Current relay

Potential relay

Electromagnetic relay

Numerical relay etc.

AIR BREAK EARTHING SWITCH

The work of this equipment comes into picture when we want to shut down the supply for

maintenance purpose. This help to neutralize the system from induced voltage from extra high

voltage. This induced power is up to 2KV in case of 400 KV lines.

INTRODUCTION

This division basically calibrates various instruments and

takes care of any faults occur in any of the auxiliaries in

the plant.

“Instrumentation can be well defined as a technology of

using instruments to measure and control the physical and

chemical properties of a material.”

C&I LABS

Control and Instrumentation Department has following

labs:

• Manometry Lab.

• Protection and Interlocks Lab.

• Automation Lab.

• Electronics Lab.

• Water Treatment Plant.

• Furnaces Safety Supervisory System Lab

THANK YOU