A star connected 3 phase, 15 MVA. 12kV alternator has a phase reactance of 10 % it is protected by Merz-Price circulating current scheme which is set to operate for fault current not less than 200 A. Calculate the value of earthing resistance to be provided in order to ensure that only 15 % of the alternator winding remains unprotected.
Synchronous Generator
In comparison to an asynchronous generator, it is a machine where the rotor speed is equal to the rotating magnetic field produced by the stator, i.e., mechanical speed is equal to the electrical speed, thus called synchronous, and not asynchronous.
Salient Pole Rotor
Salient pole rotor includes a large number of exposed poles mounted on a magnetic wheel. The construction of a bright pole is as shown in the image on the left. The proposed poles are made of metal laminations. The rotor winding is provided on these poles and is supported by pole shoes.
A star connected 3 phase, 15 MVA. 12kV alternator has a phase reactance of 10 % it is protected by Merz-Price circulating current scheme which is set to operate for fault current not less than 200 A. Calculate the value of earthing resistance to be provided in order to ensure that only 15 % of the alternator winding remains unprotected.
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