The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

Electrical Machines
The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

57.1%.

59.2%.

88.8%.

48.0%.

57.1%.

59.2%.

88.8%.

48.0%.

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Electrical Machines
If the load current and flux of a DC motor are held constant and voltage applied across it armature is increased by 5%, the speed of the motor will

Reduce by 5%.

Increase by 5%.

Depends on other factor.

Remain unchanged.

Reduce by 5%.

Increase by 5%.

Depends on other factor.

Remain unchanged.

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Electrical Machines
A load of 900 lbs is to be raised with a lift car weighting 855 lbs at a speed of 110 feet per minute, the over balance being 40 % and percentage efficiency 45 %. Find the horse power of the motor without counterweight

150.

180.

170.

160.

150.

180.

170.

160.

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Electrical Machines
If iron loss and full load copper loss of any transformer are denoted by Pi and Pc, then the load corresponding to maximum efficiency is given by

(Pi / Pc)0.5 Ãƒâ€” Full Load.

(Pi / Pc)1.6 Ãƒâ€” full Load.

(Pi / Pc)2 Ãƒâ€” full Load.

(Pi / Pc) Ãƒâ€” full Load.

(Pi / Pc)0.5 Ãƒâ€” Full Load.

(Pi / Pc)1.6 Ãƒâ€” full Load.

(Pi / Pc)2 Ãƒâ€” full Load.

(Pi / Pc) Ãƒâ€” full Load.

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Electrical Machines
For larger units high torque it is preferred to use

Partial motor.

Slip induction motor.

Universal motor.

DC shunt motor.

Partial motor.

Slip induction motor.

Universal motor.

DC shunt motor.

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Electrical Machines
When a DC cummulative compound wound motor is loaded

Torque and speed both increase.

Torque increase and speed decrease.

Torque decrease and speed increases.

Both torque and speed decrease.

Torque and speed both increase.

Torque increase and speed decrease.

Torque decrease and speed increases.

Both torque and speed decrease.

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Electrical Machines

Electrical Machines The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

Electrical Machines If the load current and flux of a DC motor are held constant and voltage applied across it armature is increased by 5%, the speed of the motor will

Electrical Machines A load of 900 lbs is to be raised with a lift car weighting 855 lbs at a speed of 110 feet per minute, the over balance being 40 % and percentage efficiency 45 %. Find the horse power of the motor without counterweight

Electrical Machines If iron loss and full load copper loss of any transformer are denoted by Pi and Pc, then the load corresponding to maximum efficiency is given by

Electrical Machines For larger units high torque it is preferred to use

Electrical Machines When a DC cummulative compound wound motor is loaded

Electrical Machines
The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

Electrical Machines
If the load current and flux of a DC motor are held constant and voltage applied across it armature is increased by 5%, the speed of the motor will

Electrical Machines
A load of 900 lbs is to be raised with a lift car weighting 855 lbs at a speed of 110 feet per minute, the over balance being 40 % and percentage efficiency 45 %. Find the horse power of the motor without counterweight

Electrical Machines
If iron loss and full load copper loss of any transformer are denoted by Pi and Pc, then the load corresponding to maximum efficiency is given by

Electrical Machines
For larger units high torque it is preferred to use

Electrical Machines
When a DC cummulative compound wound motor is loaded