A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

78.5%

67.5%

82.5%

72.5%

78.5%

67.5%

82.5%

72.5%

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Electrical Machines
In a transformer, hysteresis and eddy current losses depend upon

load current

supply frequency

both 2 and 3

maximum flux density

load current

supply frequency

both 2 and 3

maximum flux density

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Electrical Machines
For same HP rating and full load speed which of following motor has poor starting torque?

Series.

Differently compounded.

Cummulative compound.

Shunt.

Series.

Differently compounded.

Cummulative compound.

Shunt.

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Electrical Machines
The armature of DC machine is made of silicon steel lamination to

reduce both eddy current and hysteresis loss.

increase the permeability.

reduce hysteresis loss only.

reduce eddy current loss only.

reduce both eddy current and hysteresis loss.

increase the permeability.

reduce hysteresis loss only.

reduce eddy current loss only.

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Electrical Machines
The output power indicated on the name plate of any motor is always the

Power drawn in KW.

Output power at the shaft.

Gross power.

Power drawn in KVA.

Power drawn in KW.

Output power at the shaft.

Gross power.

Power drawn in KVA.

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Electrical Machines
In a DC machine

current and emf in armature are alternating.

current and emf at the terminals are alternating.

emf in armature conductors and at the terminals is alternating.

current and emf in armature are unidirectional

current and emf in armature are alternating.

current and emf at the terminals are alternating.

emf in armature conductors and at the terminals is alternating.

current and emf in armature are unidirectional

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Electrical Machines

Electrical Machines A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines In a transformer, hysteresis and eddy current losses depend upon

Electrical Machines For same HP rating and full load speed which of following motor has poor starting torque?

Electrical Machines The armature of DC machine is made of silicon steel lamination to

Electrical Machines The output power indicated on the name plate of any motor is always the

Electrical Machines In a DC machine

Electrical Machines
A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
In a transformer, hysteresis and eddy current losses depend upon

Electrical Machines
For same HP rating and full load speed which of following motor has poor starting torque?

Electrical Machines
The armature of DC machine is made of silicon steel lamination to

Electrical Machines
The output power indicated on the name plate of any motor is always the

Electrical Machines
In a DC machine