Basic Electricity 2, May/June 2015

Question 6

(a) List four parts of a d.c. machine.

(b) State the function of any three components mentioned in 6(a)  


The expected answers were;

(a) Substation components

(i) Transformer

(ii) Isolators

(iii) Fuses

(iv) Circuit breaker

(v) Feeder

(vi) Contactor

(b) Explanation of any three listed above

(i) Transformer; it is used to step up or step down voltage.

(ii) Fuse; it is used to break circuit on short circuit and overload.

(iii) Isolator; it is used to isolate the transformer from the system in case of a fault.

(iv) Feeder; feed the input and the output voltage of the transformer.

(v) Contactor; it is used for monitoring of electrical qualities i.e V or I in the system.

The candidates were expected to list four substation components and state the function of three of the components.

It was reported that many candidates who attempted this question could not do well.