Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 1, 2, 3 and 4 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 1, 2 and 3 1, 3 3 only ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A separately-excited DC generator, running at rated speed, has 6 volts across its armature terminals with no field current. When field winding is excited with one ampere, the voltage builds up to 250 V at no load. In case field current is reduced to zero, with the speed remaining unaltered, the armature terminal voltage would be less than 6 V more than 6 V zero 6 V less than 6 V more than 6 V zero 6 V ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines On which of the following factor/factors the speed of a DC motor depends upon? Armature current. All of these. Field flux. Applied voltage. Armature current. All of these. Field flux. Applied voltage. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A large series motor is never started without some mechanical load on it because otherwise it will produce sparking at brushes. develop excessive speed and damage itself. open fuse or circuit breaker. draw too much current. produce sparking at brushes. develop excessive speed and damage itself. open fuse or circuit breaker. draw too much current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Minimum allowable resistivity of power transformer insulating oil is generally taken as 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a DC Shunt Motor if the load current increases then field flux increases. remains constant. decreases. decreases increases. remains constant. decreases. decreases ANSWER DOWNLOAD EXAMIANS APP
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