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
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?

2166.67V, 230 rpm.

541.67V, 250 rpm.

541.67V, 200 rpm.

2166.67V, 270 rpm.

2166.67V, 230 rpm.

541.67V, 250 rpm.

541.67V, 200 rpm.

2166.67V, 270 rpm.

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Electrical Machines
Exciting current of an induction motor is

lesser than power transformer.

equal as power transformer.

higher than power transformer.

none of these.

lesser than power transformer.

equal as power transformer.

higher than power transformer.

none of these.

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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

2, 4

1, 3

2, 3

1, 4

2, 4

1, 3

2, 3

1, 4

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Electrical Machines
In salient pole synchronous machine, if direct axis reactance and quadrature axis reactance is equal, then power developed due to reluctance is

infinite value

maximum

any of the above

zero

infinite value

maximum

any of the above

zero

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Electrical Machines
A smaller air gap in a polyphase induction motor helps to

increase the starting torque.

reduce the chance of crawling.

reduce the magnetizing current.

reduce the chance of cogging.

increase the starting torque.

reduce the chance of crawling.

reduce the magnetizing current.

reduce the chance of cogging.

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Electrical Machines
Which of the following factors improve commutation in a dc machine ? 1. High contact resistance of brushes 2. High inductance of the coils undergoing commutation 3. Shifting of brushes in the direction of rotation for a generator and in the opposite direction For a motor 4. Narrow width for the commutation bars Select the correct answer using the codes given below : Codes :

1 and 3

1, 2 and 4

2, 3 and 4

1, 2, and 3

1 and 3

1, 2 and 4

2, 3 and 4

1, 2, and 3

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Electrical Machines

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 Exciting current of an induction motor is

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

Electrical Machines In salient pole synchronous machine, if direct axis reactance and quadrature axis reactance is equal, then power developed due to reluctance is

Electrical Machines A smaller air gap in a polyphase induction motor helps to

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
Exciting current of an induction motor is

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

Electrical Machines
In salient pole synchronous machine, if direct axis reactance and quadrature axis reactance is equal, then power developed due to reluctance is

Electrical Machines
A smaller air gap in a polyphase induction motor helps to