# Countercurrent Braking of DC Shunt Motor MCQ [Free PDF] – Objective Question Answer for Countercurrent Braking of DC Shunt Motor Quiz

1. Plugging is suitable for __________ type loads.

A. Gravitational
B. Electrostatic
C. Weightless

Plugging is suitable for gravitational type loads. It halts the motor operation. It can reverse the direction of rotation of the motor. It can hold the motor at zero speed.

2. In DC shunt machine ∅ is directly proportional to Ia.

A. True
B. False

In a shunt DC machine, the field winding is in parallel with the armature winding. The armature current flows through the armature winding.

IF∝∅∝Vt.

3. Braking resistance should be selected in order to limit the braking current.

A. True
B. False

During braking, a high current flows in the armature circuit. To limit the braking current a proper value of braking resistance should be selected.

4. Torque developed in the motor is ___________

A. KmΦIa
B. KmΦIa3
C. 2KmΦIa
D. KmΦIa2

The torque developed in the motor is directly proportional to the flux, machine constant, and armature current. It is mathematically represented as

T= KmΦIa.

5. Full form of TVR is _________

A. Terminal voltage reversal
B. Total voltage reversal
C. Terminal voltage redirect
D. Total voltage reversal

TVR stands for terminal voltage reversal. It is one of the methods of countercurrent braking of the DC shunt motor. It halts the motor rapidly and reverses its direction of rotation.

6. Calculate the current in DC shunt field winding using the following data: Ia=15 A, IL=21, R=22, N=484.

A. 4 A
B. 2 A
C. 7 A
D. 6 A

In the DC shunt motor, field windings are connected in parallel with the armature circuit.

IF=IL-Ia=11-5=6 A.

Motor current is the sum of field and armature current.

7. Calculate the flux produced by the DC shunt field winding using the following data: Ia=5 A, IL=11, R=2, N=4.

A. 14 Wb
B. 12 Wb
C. 17 Wb
D. 18 Wb

In the DC shunt motor, field windings are connected in parallel with the armature circuit.

IF=IL-Ia=11-5=6 A.

F=NIF=R∅.

IF∝∅.

∅=F÷R=12 wb.

8. The shape of the speed-armature current characteristics in the DC shunt motor is __________

A. Hyperbolic
B. Parabola
C. Negative slope linear line
D. Ellipse

The shape of the speed-armature current characteristics in the DC shunt motor is a negative slope linear line. The motor equation is

Eb=Vt-IaRa=Km∅ωm.

N=(Vt-IRa)/Km.

N vs Ia is a negative slope line with slope = -Ra/Km.

9. The shape of the speed-torque characteristics in the DC shunt motor is __________

A. Rectangular Hyperbolic
B. Whole x-y plane
C. Circle
D. Ellipse

The shape of the speed-torque characteristics in the DC shunt motor is a rectangular hyperbola. The motor equation is

Eb=Vt-IaRa=Km∅ωm.

N=(Vt/KmIa)-Ra/Km

Ia∝√T .

N∝1÷√T.

10. DC shunt motors are used where the high _________ is required.

A. Starting torque
B. Maximum torque
C. Minimum torque
D. Breakdown torque