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Friday, December 30, 2011

Electrical Interview questions Part 1

Electrical interview question:What is electric traction?
Answer:Traction means using the electric power for traction system i.e. for railways,trams, trolleys etc. electric traction means use of the electricity for all these . now a days, magnetic traction is also used for bullet trains. basically dc motors are used for electric traction systems.

Electrical interview question:How can you start-up the 40w tube lite with 230v AC/DC without using any choke/Coil?
Answer:It's possible by means of Electronic choke.otherwise it's not possible to ionize the particles in tube. light, with normal voltage.

Electrical interview question:What is "pu" in electrical engineering?
Answer:Pu stands for per unit and this will be used in power system single line diagram there it is like a huge electrical circuit with no of componenes (generators, transformers, loads) with different ratings (in MVA and KV). To bring all the ratings into common platform we use pu concept in which, in general largest MVA and KV ratings of the component is considered as base values, then all other component ratings will get back into this basis.Those values are called as pu values. (p.u=actual value/base value).

Electrical interview question:Operation carried out in Thermal power station?
Answer: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

Electrical interview question:Why link is provided in neutral of an ac circuit and fuse in phase of ac circuit?
Answer:Link is provided at a Neutral common point in the circuit from which various connection are taken for the individual control circuit and so it is given in a link form to withstand high Amps. But in the case of Fuse in the Phase of AC circuit it is designed such that the fuse rating is calculated for the particular circuit (i.e load) only.So if any malfunction happen the fuse connected in the particular control circuit alone will blow off.

Electrical interview question: what is the diff. btwn. electronic regulator and ordinary rheostat regulator for fans?
Answer:The difference between the electronic and ordinary regulator is that in electronic reg. power losses are less because as we decrease the speed the electronic reg. give the power needed 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 achieve speed control.

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