Electrical Machines The sparking at the the brushes, in a DC machines is due to reactance voltage. high resistance of carbon brushes. armature reaction. presence of commutator. reactance voltage. high resistance of carbon brushes. armature reaction. presence of commutator. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A shunt generator has a critical field resistance of 300 Ω at a speed of 800 rpm if the speed is raised to 1000 rpm the critical field resistance is 145 Ω. 225 Ω. 375 Ω. 150 Ω. 145 Ω. 225 Ω. 375 Ω. 150 Ω. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The following statements relate to compensating winding (CW) and interpole winding (IW) of a dc machine : 1. CW neutralizes the armature reaction under a pole pitch 2. IW is connected in series with armature circuit 3. IW produces mmf in the commutating zone only 4. CWmmf is directed along the brush axis 5. Mmf produced by IW is equal to armature mmf From these, the correct statements are 2, 3, 4 1, 2, 3, 4 and 5 1, 3, 4, 5 2, 3, 4, 5 2, 3, 4 1, 2, 3, 4 and 5 1, 3, 4, 5 2, 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The result of slip test on a 3-phase, 20 KVA, 400 V, 50 Hz connected salient pole alternator is given below- Phase value: Vmax = 100 V, Vmin = 96 V, Imax = 10 A and I min = 7 A. The direct and quadranature axis reactances are respectively 8.248 and 9.60 Ω. 14.28 and 5.54 Ω. 14.28 and 9.60 Ω. 8.248 and 5.54 Ω. 8.248 and 9.60 Ω. 14.28 and 5.54 Ω. 14.28 and 9.60 Ω. 8.248 and 5.54 Ω. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If in a sub – station there is one 132 / 33 kV transformer whose secondary is connected with primary of one 33 / 11 kV transformer, the total transformation ratio of the sub – station will be, 3. 12. 7. 4. 3. 12. 7. 4. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In salient pole synchronous machine, if direct axis reactance and quadrature axis reactance is equal, then power developed due to reluctance is maximum zero infinite value any of the above maximum zero infinite value any of the above ANSWER DOWNLOAD EXAMIANS APP
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