Direct Connected Generator Protection: Direct connected generators are normally of smaller ratings and a typical scheme of Direct Connected Generator Protection for a 30 MW generator is shown in Fig. (6.21). It consists of the…
Prime Mover Protection: In the event of prime-mover failure the machine starts motoring meaning thereby that it draws electrical power from the system and drives the prime-mover. This condition imposes a balanced load on the…
Overload Protection Relay: Overload Protection Relay - Continuous balanced overloading of a machine causes overheating in the stator winding. An obvious solution to this is the application of overcurrent relays; but this is not usually…
Unbalanced Loading Protection of Generator: Unbalanced Loading Protection of Generator - Whatever be the cause of the unbalance it is obvious that the negative phase sequence current will result in heating of the stator. In…
Loss of Excitation Protection: Two distinct effects of Loss of Excitation Protection are that the machine starts drawing magnetizing current of large magnitude from the system, and the slip frequency emfs induced in the rotor…
Rotor Protection: Rotor Protection - As pointed earlier rotor windings may be damaged by earth faults or open circuits. Figure (6.16) shows a modern method of rotor earth-fault detection. The field is biased by a…
Stator Protection: Stator Protection - The type of stator faults likely to occur have been discussed already. The earth-fault current is usually limited by resistance in the neutral of the generator. Depending upon the amount…
Generator Faults: Generator faults can be considered under the following heads. (a) Stator Faults: These include the following: Phase-to-earth faults. Phase-to-phase faults. Inter-turn faults. Most faults occur in the stator windings and their connections and…
Transformer Feeder Protection: Transformer Feeder Protection - In order to supply bulk power from a major switching station, the transformer is sometimes connected directly to the feeder without an HV switchgear at the transformer. Although…
Gas Actuated Relays: Gas Actuated Relays - When a fault occurs inside the transformer tank gas is usually generated, slowly for an incipient fault and violently for heavy faults. Most short circuits developed either by…
