Question

a) “CONT” on a motor nameplate indicates that the motor can put out _____________ power continuously.

b) ______________ DC motors have electronic commutators.

c) Stepper motors are used when precise, repeatable shaft _____________ is required.

d) Single-phase induction motors usually have a(n) ______________ winding for starting the motor.

e) Which one of these cannot be a synchronous speed? (3600, 2400, 1800, 1200, 600) rpm

f) There are five kinds of power losses in AC motors. Name them:

            1. _________________________

            2. _________________________

            3. _________________________

            4. _________________________

            5. _________________________

g) If the starting torque of the load is greater than the starting torque of the motor, the motor will ____________.

h) Most motors can supply several times their rated power for short periods of time. Ultimately, the motor _________________________ limits the power output.

i) Three-phase synchronous motors have ______________________ starting torque.

j) If an induction motor has no _______________________, its speed will approach the synchronous speed.

k) If the field is reduced on an unloaded shunt-connected motor, the motor will

(speed up, slow down, remain at the same speed).

l) A wheel on a vehicle has a diameter of 750 cm and rotates at 200 rpm. The speed of the vehicle is ____________ m/s.

m) Typical industrial motor efficiency is 85-95% at _______________ load.

n) A crank handle is 50 cm long. You push down on the crank handle with a force of 15 N. The torque on the crank is ______________ N-m.

o) Back EMF opposes the applied ________________.

p) A permanent magnet motor has the same torque-speed curve as a(n) ______________ motor.

q) What kind of motor is sometimes used without a load for power factor correction? _______________ motor.

r) What kind of motor runs at a constant speed regardless of the load? _________________motor.

s) The armature winding is on the (rotor, stator, either rotor or stator).

t) What do you call the part of a motor that rotates? ______________

u) The most common motor in the world is an induction motor with a ______________ rotor.

v) What do you call the part of a motor that does not rotate? ____________________

w) Motor brushes are usually made out of what material? ______________

x) What do you call a motor that can run on both AC and DC? ___________________________

y) EMF stands for _____________________________

z) Back EMF is proportional to the field strength and the ______________ of rotation.

Answer 1

Answer is given in between blank spaces.

a) “CONT” on a motor nameplate indicates that the motor can put out __constant___ power continuously.

b) ____Brushless_____ DC motors have electronic commutators.

c) Stepper motors are used when precise, repeatable shaft ___toque output_____ is required.

d) Single-phase induction motors usually have a(n) ___Auxilliary __ winding for starting the motor.

e) Which one of these cannot be a synchronous speed? (3600, 2400, 1800, 1200, 600) rpm

Synchonous speed = 120*f/P Here f= frequency 60Hz    and P= no. of poles in even numbers
Hence 2400 can't be synchonous speed

f) There are five kinds of power losses in AC motors. Name them:

            1. _Magnettic leakage loss________________________

            2. _Hysteresis loss________________________

            3. __Copper loss or I^2*R loss_______________________

            4. __Mechanical Loss_______________________

            5. ___Windage and friction loss______________________

g) If the starting torque of the load is greater than the starting torque of the motor, the motor will __not start __________.

h) Most motors can supply several times their rated power for short periods of time. Ultimately, the motor _________________________ limits the power output.

i) Three-phase synchronous motors have _____high _________________ starting torque.

j) If an induction motor has no _________load______________, its speed will approach the synchronous speed.

k) If the field is reduced on an unloaded shunt-connected motor, the motor will

(speed up, slow down, remain at the same speed).      slow down

l) A wheel on a vehicle has a diameter of 750 cm and rotates at 200 rpm. The speed of the vehicle is ____12.5________ m/s.

speed = angular speed * radius

m) Typical industrial motor efficiency is 85-95% at _____full__________ load.

n) A crank handle is 50 cm long. You push down on the crank handle with a force of 15 N. The torque on the crank is ________7.5______ N-m.

Torque = force * length

o) Back EMF opposes the applied ________field current________.

p) A permanent magnet motor has the same torque-speed curve as a(n) ____synchronous__________ motor.

q) What kind of motor is sometimes used without a load for power factor correction? _____synchonous__________ motor.

r) What kind of motor runs at a constant speed regardless of the load? _________sychronous________motor.

s) The armature winding is on the (rotor, stator, either rotor or stator).

either rotor or stator depending upon motor size and use

t) What do you call the part of a motor that rotates? ___rotor___________

u) The most common motor in the world is an induction motor with a ____squirrel cage__________ rotor.

v) What do you call the part of a motor that does not rotate? ____________stator________

w) Motor brushes are usually made out of what material? ______graphite________

x) What do you call a motor that can run on both AC and DC? ________universal motor___________________

y) EMF stands for _______________electro motive force______________

z) Back EMF is proportional to the field strength and the ______________ of rotation.