Wednesday, July 10, 2013

Electrical Interview questions Part 23

Q:What are the operation carried out in Thermal power station?
A: The water is obtained in the boiler and the coal is burnt so that steam is obtained this steam is allowed to hit the turbine, the turbine which is coupled with the generator generates the electricity

Q: What is the diff. btwn. Electronic regulator and ordinary rheostat regulator for fans?
A: The difference between the electronic and ordinary regulator is the fact that in electronic reg. power losses tend to be less because as we minimize the speed the electronic reg. give the power necessary for that particular speed but in case of ordinary rheostat type reg. the power wastage is same for every speed and no power is saved. In electronic regulator triac is employed for speed control. by varying the firing angle speed is controlled but in rheostatic control resistance is decreased by steps to achievespeed control.

Q: What is 2 phase motor?
A: A two phase motor is often a motor with the the starting winding and the running winding have a phase split. e. g; ac servo motor. where the auxiliary winding and the control winding have a phase split of 90 degree.

Q:What does quality factor depend on in resonance?
A:Quality factor q depends on frequency and bandwidth.

Q:What are the types of power in electrical power?
A: There are normally three types of power are counted in electrical power. They are,
· Apparent power
· Active power
· Reactive power

Q:What are the advantages of VSCF wind electrical system?
A:Advantages of VSCF wind electrical system are:
• No complex pitch changing mechanism is needed.
• Aero turbine always keeps going at maximum efficiency point.
• Extra energy in the high wind speed region of the speed - duration curve can be extracted
• Significant reduction in aerodynamic stresses, which are associated with constant - speed operation.

Q:What is slip in an induction motor?
A:Slip can be defined as the distinction between the flux speed (Ns) and the rotor speed (N). Speed of the rotor of an induction motor is always less than its synchronous speed. It is usually expressed as a percentage of synchronous speed (Ns) and represented by the symbol ‘S’.