A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

Electrical Machines
A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

field resistance was higher than critical resistance

there was no residual magnetism in the field circuit

there was a break in the armature circuit

field winding was wrongly connected

field resistance was higher than critical resistance

there was no residual magnetism in the field circuit

there was a break in the armature circuit

field winding was wrongly connected

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Electrical Machines
For a 3 - ÃŽÂ¦, 4 pole, 50 Hz IM rotating at full load speed of 1440 rpm, calculate speed of rotor field with respect to rotor structure and stator structure respectively?

60, 1500.

50, 1500.

60, 1440.

1440, 1500.

60, 1500.

50, 1500.

60, 1440.

1440, 1500.

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Electrical Machines
The shaft torque of a dc motor is less than the electromagnetic torque because of

hysteresis losses.

mechanical losses.

ohmic losses.

eddy current losses.

hysteresis losses.

mechanical losses.

ohmic losses.

eddy current losses.

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Electrical Machines
The heat transfer by convection in a transformer least depends on

air velocity.

surface area.

temperature difference.

color of the paint.

air velocity.

surface area.

temperature difference.

color of the paint.

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Electrical Machines
An 8 pole DC generator has 500 armature conductors and useful flux per pole of 0.065 Wb. What will be the emf generated if it is lap connected and runs at 1000 rpm. What must be the speed at which it is driven to produce the same emf if it is wave wound?

541.67V, 250 rpm.

2166.67V, 270 rpm.

541.67V, 200 rpm.

2166.67V, 230 rpm.

541.67V, 250 rpm.

2166.67V, 270 rpm.

541.67V, 200 rpm.

2166.67V, 230 rpm.

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Electrical Machines
With the increase in speed of a DC motor

both back emf as well as line current increase.

back emf falls and line current increases.

both back emf as well as line current fall.

back emf increases but line current falls.

both back emf as well as line current increase.

back emf falls and line current increases.

both back emf as well as line current fall.

back emf increases but line current falls.

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Electrical Machines

Electrical Machines A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

Electrical Machines For a 3 - ÃŽÂ¦, 4 pole, 50 Hz IM rotating at full load speed of 1440 rpm, calculate speed of rotor field with respect to rotor structure and stator structure respectively?

Electrical Machines The shaft torque of a dc motor is less than the electromagnetic torque because of

Electrical Machines The heat transfer by convection in a transformer least depends on

Electrical Machines An 8 pole DC generator has 500 armature conductors and useful flux per pole of 0.065 Wb. What will be the emf generated if it is lap connected and runs at 1000 rpm. What must be the speed at which it is driven to produce the same emf if it is wave wound?

Electrical Machines With the increase in speed of a DC motor

Electrical Machines
A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

Electrical Machines
For a 3 - ÃŽÂ¦, 4 pole, 50 Hz IM rotating at full load speed of 1440 rpm, calculate speed of rotor field with respect to rotor structure and stator structure respectively?

Electrical Machines
The shaft torque of a dc motor is less than the electromagnetic torque because of

Electrical Machines
The heat transfer by convection in a transformer least depends on

Electrical Machines
An 8 pole DC generator has 500 armature conductors and useful flux per pole of 0.065 Wb. What will be the emf generated if it is lap connected and runs at 1000 rpm. What must be the speed at which it is driven to produce the same emf if it is wave wound?

Electrical Machines
With the increase in speed of a DC motor