Monday, April 28, 2014

Important Diploma Electrical Questions 3

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          Important Diploma Electrical Questions 3


Q:1 What is effect of capitance in transmission line? 2. After raising the voltage at receiving end what will be happen? 3.how we nullify or control the raised voltage at receiving end?             
Answer: it is ferranti effect. the voltage at the receiving end is higher than the sending end. in order to control ferranti effect SHUNT REACTOR is place in the transmission line.

Q: 2 what is the importance of reactive power in power generation. if it is zero means wat will happen to system.                                                                                                                                                         Answer: Electrical machines work on the principle of conversion of  electromagnetic energy. A part of input energy is consumed  for creating and maintaining the magneticfield.This part of  the input energy cannot be converted into active energy and  is returned to the electrical network on removal of the  magnetic field. This power is known as “reactive” power Q. The Q Power flows back and forth, causing 90º Out of phase shift between the current and voltage waveform.This 
Reactive Power has one half of the Power In the positive area and the other half in the negative area.Unlike true power, reactive power is not useful power because it is stored in the circuit itself. This power is stored by
1)Inductors, Because they expand and collapse their magnetic fields in an attempt  to  keep  current  constant, 2) Capacitors,Because  they  charge and  discharge  in  an attempt  to  keep  voltage  constant. If it is zero than electromagnetic conversion  not possible.    

Q: 3  what is CRGO Transformers?                                                                                       
Answer: CRGO Transformers:- are the transfomrer in which the core material used is "Cold Rolled Grain Oriented " Steel. CRGO steel core is having less hysteresis losses therefore the  efficiency is high as compared to normal core transformer.

Q:4 why fuse is not used in neutral?                                                                                      
 Answer: Fuse is used to protect the equipment from abnormal  condition, equipment or load is always connectected before the nuetral point,flow of current is from phase to neutral,
so there will be no use to connect the fuse on the nuetral side. nuetral side current value is zero.

Q:5 Do you know the overhauling of a motor?                                                                       
Answer: overhauling of motor means just shutting down but the purpose is to do some maintenance and repairing of motor parts and  changing the parts if required to incresing the efficiency.
                                                                                                          Ajay Gahlot
                                                                   



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