The most commonly used relay, for the protection of an alternator against loss of excitation, is

A negative sequence relay is commonly used to protect

Consider a stator winding of an alternator with an internal high-resistance ground fault. The current under the fault condition are as shown in the figure. The winding is protected using a differential current scheme with current transformers of ratio 400/5 A as shown. The current through the operating coil is

A lossless single machine infinite bus power system is shown below:

The synchronous generator transfers 1.0 per unit of power to the infinite bus. The critical clearing time of circuit breaker is 0.28s. If another identical synchronous generator is connected in parallel to the existing generator and each generator is scheduled to supply 0.5 per unit of power, then the critical clearing time of the circuit breaker will

A list of relays and the power system components protected by the relays are given in Group I and Group II respectively. Choose the correct match from the four choices given below:

The neutral of 10MVA, 11KV alternator is earthed through a resistance of 5 ohms. The earth fault relay is set to operate at 0.75A. The CT’s have a ratio of 1000:5.

What percentage of the alternator winding is protected?