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  2. 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.
  4. 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
  6. PARTS OF A POWER PLANT 1. 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
  7. 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.
  9. 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.
  10. COOLING OF TRANSFORMERS OF LARGE MVA As 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)
  11. 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.
  12. 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.
  13. 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.
  14. 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