Q. 400-V dc shunt motor takes a current of 5.6 A on no-load and 68.3 A on full-load. Armature reaction weakens the field by 3%. What is the ratio of full-load speed to no-load speed? Given: Ra = 0.18 Ω, brush voltage drop= 2 V, Rf = 200 Ω.

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Q. In which of the following method, effect of armature reaction is more?

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Q. Which of the following DC motor has the poorest speed control?

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Q. In variable speed motor ____________

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Q. The speed of a motor falls from 1200 rpm at no-load to 1050 rpm at rated load. The speed regulation of the motor is ____________

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Q. Which of the following is not the method of speed control in DC series motor?

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Q. For speed reversal, field control method is suitable.

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Q. For large motors what is the ratio of compensating winding is required for increasing the speed of the motor?

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Q. In diverter resistor field control method of DC series motor, variable resistor is added ________

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Q. Why it is advisable to use inductively wound diverter resistor?

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Q. For higher diverter resistance, speed-torque characteristic will lie ____________

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Q. In tapped field control method ____________

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Q. Which of the following method will not give many speed values for a DC series motor?

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Q. In series-parallel speed control method ______________

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Q. Where diverters are used?

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Q. What will happen to the speed of a series motor if the temperature of armature resistance is increased?

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Q. For which speed control method we get minimum efficiency?

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Q. The speed of a DC motor can be varied by changing ______________

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Q. For constant torque drive which of the following speed control method is preferred?

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Q. When the armature of a DC motor rotates, emf induced is in machine is called as ___________

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