transformers

1. “DIFFERENT TYPES OF
TRANSFORMERS USED FOR
210MW UNIT THERMAL POWER
PLANT”
PRESENTED BY - NEN BAKRANIYA.

2. •Overview
• Introduction
• Single line diagram
• Classification of transformer
• Parts of transformer
• Cooling system
• Protection of Transformer

3. • TRANSFORMER
• “Transformer is a static device which transform electric power of
one circuit to
• another circuit without changing its frequency.”
• Working Principle of transformer :
• The working principle of transformer depends upon Faraday’s law of
• electromagnetic induction. Actually mutual induction between two or
more
• winding is responsible for transformation action in an electrical
transformer.
• Faraday’s laws of Electromagnetic Induction:
• According to Faraday’s law,
• “Rate of change of flux linkage with respect to
• time is directly proportional to the induced EMF

4. •Types of Transformers used in
• 210MW unit
• 1) Generator Transformer 2) Station Transformer
• 3) Distribution Transformer 4) Unit auxiliary Transformer
• 5) Instrument Transformer 6) Rectifier Transformer
• 7) Neutral ground Transformer
• 8)Transformer used for general purposes and for different processes.
• i ) Welding Transformer
• ii ) Specially designed Transformer used for X ray, Radio,
• Telecommunication, T.V., High frequency heating, and Industrial
• heating for different processes.

5. GENERATOR TRANSFORMER

6. •Generator Transformer Rating
• MVA = 240 MVA
• Primary Side = 15.75 KV (d)
• Secondary Side = 400 KV (Y)
• Oil Qty = 43 KL
• Cooling = OFWF
• Vector Group = Yd11
• %Z = 11.90

7. •Functions
• This is step up transformer of high voltage capacity.
• This is connected after the generator to step up voltage
• from 15.75kv to 400kv.
• The main function of this transformer is to step up
• voltage so as to reduce transmission losses, line drop
• and increases Transmission efficiency .

9. •Station Transformer Rating
• MVA = 40 MVA
• Primary Side = 220 KV (Y)
• Secondary Side = 6.6 KV (Y)
• Oil Qty = 30 KL
• Cooling = ONAF
• Vector Group = Yy0
• %Z = 11

10. •Functions
• Transformer at the generating station is required for
• starting of the generating units when they are either
• newly constructed or taken of the bar for overhaul.
• These Power transformers are called station
• transformer, which receives power from the grid and
• feed power-to-power station distribution system.

12. •Unit Auxiliary Transformer Rating
• MVA = 20 MVA
• Primary Side = 15.75KV (d)
• Secondary Side = 6.6 KV (Y)
• Oil Qty = 6.4 KL
• Cooling = ONAF
• Vector Group = Dy1
• %Z = 9.0

13. •Functions
• • The Purpose of Unit auxiliary Transformer is to feed power to generator
• auxiliaries of that unit
• • These transformers are connected to generators and are used as stepping
• down transformers. The HV side transformer voltage corresponds to the
• voltage of the generating unit and the LV side voltage is stepped down to
• 6.6KV
• • Rated KVA of Unit Auxiliary Transformers is approximately 15% of the
• generating rating
• • Usually these transformers are outdoor transformers
• • One Unit auxiliary transformer is present for every generating unit.

14. RECTIFORMER
• A Rectiformer is a rectifier and
transformer designed and built as a
single entity for converting alternating
current into direct current.
• It is piece of power systems
equipment rather than an electronics
component.
• Rectiformers are used for supplying
power to different field of ESP
(electrostatic precipitator).

15. INSTRUMENT TRANSFORMER
FOR METERING AND PROTECTION TO MAINTAIN INSTRUMENT ACCURACY.
FOR SENSING H.T. SIDE CURRENT AT THE SECONDARY SIDE
USED IN PROTECTION RELAY, TRIP COILS AND PILOT WIRES.
USED IN CURRENT POWER MEASUREMENT, TEMPERATURE SENSING ETC.
Current Transformer (CT) Potential Transformer • Potential Transformer (PT)

16. CURRENT TRANSFORMER

17. POTENSIAL TRANSFORMER

18. DISTRIBUTION TRANSFORMER
THIS IS STEP DOWN TRANSFORMER
CONNECTED ACCORDING TO
APPLICATIONS SUCH AS BOILER ,TURBINE ,
STATION SERVICE
BOARD.
THE MAIN FUNCTION OF THIS
TRANSFORMER IS TO PROVIDE
CONVENIENT AMOUNT OF POWER IN THE
VARIOUS BOARDS.

19. NEUTRAL GROUNDIG TRANSFORMER

20. •NGT
• The subject of grounding covers the problems relating
• to the conduction of electric current to the earth and
• through the ground. The earth rarely serves as a part of
• the return circuit, being used mainly for fixing the
• potential of circuit neutrals.
• The ground connection improves service continuity
• and protects lives and equipment.

21. •Advantages of Neutral Grounding
• Transformer
• (a) Arcing rounds are reduced or eliminated.
• (b) The neutral grounding stabilises the neutral point.
• (c) By employing resistance or reactance in earth connection, the earth fault current can
• be controlled.
• (d) The over voltage surge due to lightening are discharged to earth hence less damages
• to the equipment. Useful amount of earth fault current is required to operate earth fault
• relay.
• (e) Improved service reliability due to limitation of arcing ground and prevention of
• unnecessary tripping of circuit breakers.
• (f ) Life of eqipment, machines and installation is improved due to limitation of
• voltages.
• (g) Greater safety to personnel and equipment due to operation of fuses or relay on
• earth fault and limitation of voltages. Hence it is economical to ground neutral point.

22. •Constructional Features
• Main Tank
• Laminated core
• Core winding
• Bushing
• Tap changer
• Conservator
• Breather
• Explosion vent / Pressure relief valve

24. •MAINTENANCE IN TRANSFORMER
• Breather condition monitoring
• Oil testing
• Transformer Oil Level Checking
• D. G. A.
• Oil Filtration
• Bushing Cleaning
• Drying Out (after 7 Yrs)

25. •THANK YOU