Observation

Expected response:
(a) (i)         Requirements for IEE regulations on electric motor control                                                     - means of excess current protection
- means of preventing automatic restarting of motor after failure of supply
- means of isolating a motor from the supply (voltage)
- means of starting and stopping motor must be close to the motor
- means of protection against overloading of the motor
- the size of cable supplying motor must be capable of carrying starting and full-
   load currents

(ii)     Factors that should be considered when choosing electric motor           
- type of supply available
- need for speed control
- type of mounting
- type of enclosure
- environment where the motor is to be installed
- type of load/power rating
- cost (implication)

(b)             Materials used for winding                                                                         
- leather fishing rod    - sleeving                                - binding rope 
- prespan                      - enamel copper conductor     - vanish
- solder                        - masking tape

(c)     (i)        Steps for effective pole test in electrical installation                                             
- switch off the supply
- remove all lamps
- put off all appliances
- all switches must be in OFF position
- neutral link must be connected
- fuse must be OFF

(ii)     Instrument required for a pole test                                                            

• ohmeter / multimeter
• bell set

       
(iii)    Expected minimum reading in pole test                                                                

• zero reading on ohmetre
• continuity on bell set         

                     
(d)     Explanation of the following terms
(i) pole pitch - this is the distance between the centre line of the adjacent poles on the electrical machines.                                                                                             
or
pole pitch is the distance measured on the circumference of the armature from the centre of one pole to the centre of the next pole

(ii)      slot pitch - this is the distance between successive slots around the periphery of an armature.                                                                                            
(iii)     skimming – this is the cleaning of dirty slip ring/armature by using emery cloth or sand paper                                                                                        
(iv)     under cutting – this is the process of reducing/removal of the mica insulation on the commutator bars        

(e)       Characteristics of a Conductor                                                      
- conductivity
- low resistance
- ductility
- high temperature coefficient
- can be soldered
- mechanical strength
- malleability