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Q9. With reference to the protective devices fitted to a main alternating current generator, explain EACH of the following:

(a) overcurrent and short circuit protection; (2)

(b) generator negative phase sequence; (2)

(c) loss of field (excitation); (2)

(d) undervoltage; (2)

(e) reverse power. (2)

Q10. (a) State the consequences of using direct online starters for comparatively large-sized a.c. induction motors. (2)

(b) Describe, with the aid of a sketch, an electronic soft starting system that may be used for large-sized a.c. induction motors.  (8)

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)

Q11. (a) Explain the principle of operation of an insulation resistance test, stating why the test is carried out on a regular basis. (6)

(b) Describe how EACH of the following electrical tests is carried out:

(i) resistance; (2)

(ii) continuity. (2)