Free Printable 3 phase motors principles

1.

What type of supply is connected to a 3 phase motor?

a)

ac

b)

dc

c)

neither, it's a generator

2.

Which part in a 3 phase motor provides the motion in the drive shaft?

a)

Armature

b)

Stator

c)

Rotor

d)

Field winding

3.

In a 3 phase motor, where is the rotating magnetic field produced?

a)

Rotor

b)

Stator

c)

Armature

4.

The speed of the RMF is symbolised by the letters

a)

n_r

b)

n_s

c)

f

d)

rms

5.

The speed of the motor is symbolised by the letter?

a)

n_r

b)

n_s

c)

f

d)

rpm

6.

In the equation to calculate the synchronous speed the letter 'p' denotes the

a)

number of poles

b)

number of pole pairs

c)

number of primary poles

d)

voltage on the primary

7.

The equation used to calculate the speed of the RMF is?

a)

$n_s=\frac{f}{p}$

b)

$n_s=\frac{p}{f}$

c)

$n_r=\frac{f}{p}$

d)

$n_r=\frac{p}{f}$

8.

The slip of a motor is the

a)

difference between the synchronous speed and he pole pairs

b)

efficiency of the motor

c)

difference between the pole pairs and the frequency

d)

difference between the rotor speed and the synchronous speed

9.

The equation used to calculate the per unit slip is

a)

$\frac{n_s-n_r}{n_s}\ x\ 100$

b)

$\frac{n_r-n_s}{n_r}$

c)

$\frac{n_r-n_s}{n_r}x\ 100$

d)

$\frac{n_s-n_r}{n_s}$

10.

If the synchronous speed of a 3 phase motor is 120rpm and the slip is 3%, what is the rotor speed?

a)

3.6rpm

b)

116.4rpm

c)

4000rps

d)

123.6rpm

11.

Which type of motor uses the difference in csa between the run and the start winding to cause rotation in the rotor?

a)

Shunt wound

b)

3 phase induction motor

c)

Resistance start

d)

Capacitor start

12.

An application of an induction motor is

a)

Drill

b)

Vacuum Cleaner

c)

EV

d)

Lift

13.

Application of a universal motor is

a)

Lift

b)

EV

c)

110V drill

d)

Washing machine

14.

What does the capacitor do in a capacitor start motor?

a)

Decrease phase shift increasing starting torque

b)

Increase phase shift decreasing starting torque

c)

Decrease phase shift decreasing starting torque

d)

Increase phase shift increasing starting torque

3 phase motors principles

Total questions: 14

Worksheet time: 7mins

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