Saturday, August 10, 2013

Electrical Interview questions Part 24

Q:Why link is provided in neutral of an ac circuit and fuse in phase of ac circuit?
A: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.

Q:State the difference between generator and alternator
A:Generator and alternator are two devices, which converts mechanical energy into electrical energy. Both have the same principle of electromagnetic induction, the only difference is that their construction. Generator persists stationary magnetic field and rotating conductor which rolls on the armature with slip rings and brushes riding against each other, hence it converts the induced emf into dc current for external load whereas an alternator has a stationary armature and rotating magnetic field for high voltages but for low voltage output rotating armature and stationary magnetic field is used.

Q:What is ACSR cable and where we use it?
A:ACSR means Aluminium conductor steel reinforced, this conductor is used in transmission & distribution.

Q:What is the voltage gain or transfer function of amplifier?

Q: What does the KVAR means?
A:The KVAR indicates the electrical power. KVAR means “Kilo Volt Amperes with Reactive components”

Q:Why use the VCB at High Transmission System ? Why can't use ACB?
A:Actually the thing is vacuum has high arc queching property compare to air because in VCB ,the die electric strengths equal to 8 times of air . That y always vaccum used as inHT breaker and air used as in LT .

Q:What is the difference between MCB & MCCB, Where it can be used?
A:MCB is miniature circuit breaker which is thermal operated and use for short circuit protection in small current rating circuit. MCCB moulded case circuit breaker and is thermal operated for over load current and magnetic operation for instant trip in short circuit condition.under voltage and under frequency may be inbuilt. Normally it is used where normal current is more than 100A.