Electric Drives (3160919) MCQs

MCQs of DC motor characteristics

Showing 31 to 40 out of 71 Questions
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31.

Which DC motor is preferred for constant speed?

(a)

Compound motor
(b)

Series motor
(c)

Shunt motor
(d)

Differential motor
Answer:

Option (c)

32.

The direction of rotation of D.C series motor can be changed by

(a)

Interchanging field terminal
(b)

Interchanging supply terminal
(c)

Both a & b
(d)

None of the above
Answer:

Option (a)

33.

When the speed of D.C motor is increased

(a)

Back E.M.F increases and current drawn decreases
(b)

Back E.M.F decreases and current drawn increases
(c)

Back E.M.F and current drawn both increases
(d)

Back E.M.F and current drawn both decreases
Answer:

Option (a)

34.

The starting resistance of D.C motor is generally

(a)

High
(b)

Infinite
(c)

Low
(d)

None of the above
Answer:

Option (c)

35.

Which of the following will decrease when the supply voltage of a D.C motor is increased?

(a)

Operating speed
(b)

Starting Torque
(c)

Full-Load Current
(d)

No load current
Answer:

Option (c)

36.

If  Ta be the armature torque and Ia be the armature current then which of the following relation is valid for DC series motor before saturation?

(a)

Ta ∝ Ia
(b)

Ta ∝ Ia2
(c)

Ta ∝ 1/Ia
(d)

Ta ∝ 1/Ia2
Answer:

Option (b)

37.

When the ratio of back E.MF to applied voltage is ___ than the mechanical power develop by the shunt generator is maximum?

(a)

1
(b)

0.5
(c)

2
(d)

3
Answer:

Option (b)

38.

 The condition for maximum power in D.C motor is

(a)

Back emf (Eb) = Supply voltage (Vs)
(b)

Eb = 1/2 Vs
(c)

1/2 Eb = Vs
(d)

Eb = 2 × Vs
Answer:

Option (b)

39.

 In a DC shunt motor if field current is decreased then the speed of the motor is

(a)

Decrease
(b)

Increase
(c)

Remain same
(d)

None of the above
Answer:

Option (b)

40.

 In D.C motors Diverters are used in

(a)

Cumulative compound motors
(b)

Differentially compound motors
(c)

Shunt motors
(d)

Series motors
Answer:

Option (d)

Showing 31 to 40 out of 71 Questions
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