In this Post, we will Discuss the Top Electrical Engineering Interview Questions and Answers.
Electrical Engineering Interview Questions and Answers
Q1.What is electrical Generator?
Ans. A Generator is an electrical machine which converts mechanical energy into electrical energy. There are two types of generator – AC generator & DC generator.
Q2. What is the difference between a generator and alternator?
Ans. Here are the following differences are noted as.
1> Both works on the same principle of electromagnetic induction, the generator generates D.C through commutator while the alternator generates A.C through slip rings.
2> In the generator the field is fixed and the armature is rotating while in alternator armature is fixed and field is rotating.
3> Generator is used where small loads while the alternator is used for large loads or large power plants.
4> Operation and flexibility of alternator is more than the generator.
Q3. What are the types of winding used in the electrical machine?
Ans. There are two types of winding is generally used as
wave winding and lap winding.
In wave winding the no. of the parallel path is two, whereas in the lap winding the no. of the parallel path is equal to no. of poles.
Q4. What is the power factor?
Ans. It is the cosine angle between voltage and current in an ac circuit.
Q5. What is meant by H.R.C fuse?
Ans: In electrical system fuse acts as a protection device and depending on application different type of fuse is to select. Out of these different type of fuses, HRC is also one of the types and it stands for ” High Rupturing Capacity”.This type of fuses normally used where some delay is acceptable for protecting the system.
Q6. What is an induction motor? and how to control its speed?
Ans: Induction motors are AC motors and they rely on the principle of Induction thus called induction motors. Three phase supply is given to the stator and with the help of the revolving magnetic field produced by it, current is induced in the rotor. Then this itself generates a magnetic field opposite to the one generated by the stator. These two fields react with each other to produce rotor movement.
Speed may be controlled either by varying input frequency or by changing the no. of poles of the motor. Obviously changing the no. of poles of the motor is not possible unless you alter the motor design or its a specialized multi-winding motor. So we have to settle for the other option i.e. change the input frequency. This can be accomplished with the help of VFD (Variable Frequency Drives). VFD allows you to control the input frequency and thus the speed of the motor.
Q7. What will happen if DC supply is given on the primary of a transformer?
Ans: Mainly transformer has high inductance and low resistance.
in case of DC supply inductance will not act only resistance will act in the circuit.
So high current will flow through the primary side of the transformer. for this reason, coil and insulation will burn out.
mathematical reason is, that the net impedance of a system is
here X = 2*pi*f*L since f = 0 in DC, X also becomes 0. hence Z also =R
which is very small in this case. When the voltage applied will be like short circuit hence the winding will burn.
Q8. What is the difference between MCCB & MCB?
Ans: MCB- The full form of MCB is “Miniature Circuit Breaker.”
MCB’s occupies less space.
MCB’s can be used even in the houses.
MCB’s ranges from 1Amps to 63Amps.
MCB’s breaking capacity 10KA, 15KA & 25KA.
MCB’s can be used without enclosures but this is safer.
Full Form of MCCB is “Moulded Case Circuit Breaker”
MCCB’s occupies more space.
MCCB’s can’t be used for small applications because of its
MCCB’s ranges from 32Amps even up to 1200Amps and more.
MCCB’s breaking capacity starts at 15KA.
Q9. What is the effect of power factor on the transformer?
Ans: If the PF is more the efficiency will be more.
Q10. What is the classification of the transformer?
Ans. The transformer is classified as,
1. According to winding – Core type winding and shell type winding.
2. According to voltage- High voltage transformer ( H.T) and low voltage transformer(L.T).
3. According to cooling – Natural oil cooling, natural oil forced air cooling, forced air forced oil cooling.
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