Q9. With reference to overcurrent protection for electrical circuits:
(a) Explain THREE methods of protection, stating where EACH may be used; (6)
(b) explain, with the aid of a diagram, the meaning of the term inverse current time characteristic. (4)
Q10. With reference to three-phase induction motor starters:
(a) explain why star-delta starters are employed; (2)
(b) explain what is meant by reduced voltage starting in the context of star-delta starters; (2)
(c) explain, with the aid of a power circuit, the sequence of operation of a start-delta starter. (6)
Q11. Explain the meaning of EACH of the following types of electrical equipment:
(i) intrinsically safe; (2) (ii) flameproof; (2) (iii) increased safety; (2)
(iv) pressurised enclosure. (2)
(b) State TWO types of lighting equipment that may be installed in the pump room areas of a crude petroleum carrier. (2)
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