Electrical Machines DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of Heavy sparking at the first stud of starting resistance steps. None of these. Heavy sparking at brushes. Both of above. Heavy sparking at the first stud of starting resistance steps. None of these. Heavy sparking at brushes. Both of above. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature mmf in a dc machine is 1. stationary with respect to field poles 2. stationary with respect to armature 3. rotating with respect to field poles 4. rotating with respect to armature From these, the correct answer is 1, 4 1, 3 2, 3 2, 4 1, 4 1, 3 2, 3 2, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In DC machines shape of net flux density is? flat tapped or trapezoidal sine wave peaky in nature saddle shape flat tapped or trapezoidal sine wave peaky in nature saddle shape ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Counter emf of a DC motor helps in energy conversion. aids applied voltage. regulates its armature voltage. exceeds supply voltage helps in energy conversion. aids applied voltage. regulates its armature voltage. exceeds supply voltage ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A single-phase transformer has its maximum efficiency at 60 percent of full load. At full load copper loss will be less than core loss. more than core loss. zero. equal to core loss. less than core loss. more than core loss. zero. equal to core loss. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For a DC Shunt Motor having armature resistance of 0.5 Ω and 2A armature current at no-load, when the armature current is changed to 20A at loaded condition the speed is 1000 r.p.m. What is the speed at no-load? 963.8 r.p.m. 1037.5 r.p.m. 4575.4 r.p.m. 1130 r.p.m. 963.8 r.p.m. 1037.5 r.p.m. 4575.4 r.p.m. 1130 r.p.m. ANSWER DOWNLOAD EXAMIANS APP
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