Observation

This is a test of practical question. Majority of the candidates did not understand the concepts being tested.
In part (a), majority of the candidates could not name the labelled parts of the a.c. motor.
In part (b), majority of the candidates could not state the function of each of the labelled parts correctly.
In part (c), majority of the candidates could not outline three steps to be taken in dismantling the motor. In addition they could not list four tools needed to dismantle the motor.
In part (c), majority of the candidates could not outline five steps in the procedure for rewinding a motor.
In part (e), majority of the candidates could not give two differences between an a.c. and a d.c. motor. However, some of them could state the applications of a.c. motors.

The expected answers include:
I - (squirrel-cage) rotor
II- stator coil / stator winding
III- shaft
IV – feet / bed/ base plate  

(b)FUNCTIONS OF THE LABELLED PARTS I - it is used to transmit / drive / move the motor forces to the output shaft
II - it is the part of the motor that receives current / that produces magnetic field / flux
III - it is used to drive the external load / it carries the bearing / fans
IV – it serves as a support to the motor / it gives the motor balance

(c)(i) STEPS IN DISMANTLING A MOTOR
- mark out the two end shields for easy identification
- loose the bolts / nuts
- gently tap the shaft from one end (with mallet / wood}
- remove the two end plates gently
- arrange the parts neatly to avoid loss / damage

(ii)TOOLS NEEDED TO DISMANTLE A MOTOR
- centre punch
- spanner / allen key
- wooden hammer/mallet
- screw driver

(d)(i) The motor would not work/start/run

(ii)STEPS IN THE PROCEDURE FOR REWINDING A MOTOR
- take data of the winding (noting the connection, span and number of turns)
- take the cross-sectional area of the coil / winding
- remove the winding
- wash / clean the stator
- insulate the stator
- rewind the coil / wind using a former / winding machine
- insert the coil/ winding into the stator
- connect the coil / winding
- bind the coils / winding together
- apply vanish to the coil
- bake / dry the coil
- test again and assemble

(e)(i)DIFFERENCES BETWEEN AN A.C. AND A D.C. MOTOR

(ii)APPLICATIONS OF A.C. MOTORS
- saw milling machines
- electric fans
- compressors in refrigerators / a.c. compressors
- washing machines