Alternators MCQs

A synchronous generator connected to an infinite bus is overexcited. Considering only the reactive powe, from the point of view of the system, the machine acts as

The neutral of 10 MVA, 11 KV alternator is earthed through a resistance of 5 ohms. The earth =fault relay is set to loperate at 0.75 A. The CT's have a ratio of 1000/5. What percentage of the alternator winding is protected?

A power station consists of two sychronous generators A and B of ratings 250 MVA and 500 MVA with inertia 1.6 p.u. and 1 p.u., respectively on their own base MVA ratings. The equivalaent p.u. inertia constant for the system on 100 MVA common base is

Test (A) No load and Blocked rotor test (B) Sumpner's test (C) Swinburn's test (P) Transformer (Q) Induction machine (R) Synchronous machine (S) DC machine

Higher synchronous reactance is preferred in the present day alternators, because one can have

A there phase alternator is wound with a 60 degree phase-spread armature windings and develops 300 kVA. If the armature is reconnected utilizing all the coils for single phase operation with a phase spread of 180 degrees, the new rating of the machine is

The phase sequence of a three-phase alternator will reverse if

A single-phase, 2000 V alternator has armature resistance and reactance of 0.8 ohms and 4.94 ohms respectively. The voltage regulation ofthe alternator at 100A load at 0.8 leading power-factor is

Xd, X'd and X"d are steady state d-axis synchronous reactance, transient d-axis reactance and sub-transient d-axis reactance of a synchronous machine respectively. Which of the following statements is true?