MGVCL Exam Paper (30-07-2021 Shift 1)
An eight-pole wave-connected armature has 600 conductors and is driven at 625 rev/min. If the flux per pole is 20 mWb, determine the generated emf.
Let, E→EMF in volt φ→Flux in weber A→Parallel path (for wave winding = 2) Z→No. of armature conductors N→speed in rpm P = Number of poles E = PφNZ/(60A) E = 8*0.020*625/(60*2) E = 500 V
The magnitude of earth fault current for a given fault position within a winding demands upon the winding connections and method of neutral grounding. Earth fault protection for an electric motor is provide by instantaneous relay having a setting of approximately 30% of motor rated current in the residual circuits of two CTs and with ground wire.
In FDLF method, B' corresponds to susceptance of unknown of PQ and PV bus Order of B' matrix is = (n -1)*(n - 1) Where n is total no. of buses. Order of B'' = (n - m - 1)*(n - m - 1)