MACHINES ONE LAB TEST QUESTIONS.
QUESTION 1.
(a) Why are the exciters poles in DC machines broad ended?
(b) Why is the armature of a DC machine always made to be therotor?
(c) Give three main advantages of transformers no load andshort-circuit tests. Include circuit diagrams
(d) Explain why the short-circuit test is said to help determinethe full-load copper losses. Use elaborate labelled diagram as wellas formulas in your explanation.
(e) Explain why Zambia electricity supply corporation limiteduses back to back no-load test. Draw the circuit diagram for thatarrangement.
(f) A 220V/12V transformer is supplied from a car battery on itssecondary side. Explain the behaviour of the machine in termsof:
1. Output voltage, transient and steady
2. Power dissipated and output
3. Usefulness compared to AC input
