POWER PLANT MEDIUM TYPE QUESTION ANSWERS 2017:-
TODAY WE DISCUSSED ABOUT THE MEDIUM TYPE QUESTION ANSWER FOR POWER PLANT THESE QUESTION ANSWER ARE VERY IMPORTANT FOR EVERY PERSON WHO BELONGING TO POWER SECTOR ANS ALSO HELPFUL FOR WHO PREPARED FOR THE BOILER FIRST CLASS AND ENERGY MANAGER OR ENERGY AUDITOR ALSO WHO PREPARED FOR THE BOE ( BOILER OPERATION ENGINEER ) EXAMINATION . THESE QUESTIONS ANSWERED BY THE WE EXPERIENCE PERSON WHO BELONGING THE POWER SECTOR . LETS US STUDY HOPE YOU LIKED IT . IF YOU LIKED IT PLEASE SHARE AND GIVE A THANKS MSG IN COMMENT BOX.
Q. What are the effect when bed hight in cfbc will be increased?
-Bed temperature will not increase as required for proper steam flow for given load in turbine as a result more PA air to be supplied and pa fan load increases and wind box pressure also get increased.
-Proper combustions not take place when bed height is more it will effects of boiler loading, then Main steam flow automatically come down when bed height is higher sides, wind box pressure is getting increases it will leads to Boiler MFT, LOI Will increase.
Q. Explain Grounding & its types why it is Important?
ANS. Purpose of grounding is just to protect equipment and circuit in case of short circuit fault and also to protect person who get contact with energized equipment’s
What actually happens how grounding protects Grounding of land or area where equipment’s are installed is done by digging area through rods some other methods are also used usually resistance of earth for protection is .5 ohm Wires from equipment body directed to grounded area in case of fault short circuit current will flow directly towards ground and keep equipment safe
-LT Earthing,HT earthing . Bonding,Lightning earthing , Restive earthing , Captive earthing, Earth return for single phase MV , Isoloc .
-Grounding is used for the protection of the equipment / eg. Transformer neutral is grounded for the protection.
Q. What is the possible reason when safety valve not operated above set point?
ANS. Safety setting May be disturbed.
Q. What is the effect when bed height in cfbc will be increased?
ANS. Bed temperature will not increase as required for proper steam flow for given load in turbine as a result more PA air to be supplied and pa fan load increases and wind box pressure also get increased..
-Proper combustion not take place when bed height is more it will effects of boiler loading, then Main steam flow automatically come down when bed height is higher sides,wind box pressure is getting increases it will leads to Boiler MFT, LOI Will increase.
– When you increase the bed highet, PA fan load increased. Fluidization shall be good and carbon loss will be minimum.
Q. Can we increase power generation up to 9.5mw from 8mw power plant? If possible then what are the modification required in plant?
ANS. There are a lot of limitations that come into play. Not knowing which type of turbine you are using. But among these limitations are cavitation, insufficient energy input, shaft position, temperatures, cooling system, field circuit (excitation), rotor circuit, stator cable take off,TX rating and winding temperatures. All these affect generation capacity.
– Every Plant has 10% extra margin I.e allowances in control valve opening. Excess MW generation can possible that is called VWO.
-Very wide Operation, that is OEM provide in PG Test report how much extra power u can generate safely and smoothly.
-we have two variables ,i.e MECR and MECR let me explain,mcr is maximum continuous rating and MECR is maximum economic continuous rating, it possible where MECR is lower the MCR .or where over load bypass valves r provided ,the machine must have the capacity to carry the Extra load.
Q. What is the relation between steam flow and load?
ANS. directly proportional
Q. Why we need start excitation system before turbine synchronization process. What is actually happen when we started the excitation system in turbine or generator?
ANS. the generator can be loaded , an excitor is a dc generator it supplies dc power to generator stator core ,thn the alternator rota core rotates in between thus power is generated in stator then supplied via busbars to distribution points.
-If we supply dc to stator core how can we get output from stator where we already applying dc In actual dc is supplied to rotor winding upon rotation this current changes across stator induces emf there which is output of generator
-Excitation is nothing more than creating a dc current in generator rotor winding This dc current vector upon rotation of generator shaft moves across stator winding(winding on stationery part) of generator inducing an emf (voltage) there according to Faraday law of electromagnetic induction “A changing magnetic field across a conductor induces emf there”Dc current can be obtained by rectification of ac Can also be get from batteries Or from dc generator.
-so that the generator can be loaded ,an excitor is a dc generator ,which supplies dc power to the rotating armature core as it rotates power is generated in the stator core the fed to the distribution points via busbars.
-A generator is mainly composed of two parts. The rotor and the stator. Rotor of generator is connected with the common shaft of tandem compounding turbine. Both rotor and stator has copper winding on it in the specified grove. Now at the start of the unit, the turbine is put into turning gear. The rotor along with the common shaft starts rotating. DC current is then supplied to the generator rotor winding by the excitor just to magnetize it. Thus a magnetic flux is created and this magnetic flux is then cutted by the rotation of the rotor. Ultimately an electro motive force is induced on the stator winding obeying the Faraday’s law of electromagnetic induction. The voltage of the Produced current is then stepped up with a transformer just to minimize the transmission loss.
-THE EXCITATION VOLTAGE GIVES DC POWER TO THE ROTOR COILS WHICH IN CAUSES IT TO GENERATE ELECTRICITY
Q. What is the corona effect in thermal power plant?
Ans. 1.The ESP works on the principle of Corona effect.
2. There is a Transformer Rectifier set which gives a high DC output .(kV and mA)
3.The –ve terminal of the TR set is connected to the Rigitrode system and the +ve terminal to the collecting plates which are already earthed.
4.Due to the high potential difference, the –ve ions move from the Rigitrodes to the collecting plates. This is called corona effect.
-Corona effect occurred in th electrical transmission line conductor , when the transmitted voltage go to beyond the 32 kv , a faint glow I.e. ozone appears around the conductor and creates of power loss , interference to communication lines and many other problems. And effect can be overcome by increasing the diameter of conductor , increasing spacing between the conductors etc…It has both +ve and – ve effect on transmission line ..
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