Q9. Describe, with the aid of a diagram, a shaft generator that uses a frequency converter. (10)
Q10. With reference to a.c switchboards:
(a) State with reasons, the protective devices that are fitted; (5)
(b) state why a breaker may fail to open under prolonged low voltage conditions. (2)
(c) explain the actions to be taken should a main generator circuit breaker stay connected despite repeated efforts to trip it off the board. (3)
Q10. With reference to overload protection for electric motors, describe the principle of operation of EACH of the following types of overload relay
(a) Thermal (3)
(b) Magnetic (3)
(C) Electronic (4)
Q11. (a) Explain, with the aid of a sketch, the principle of operation of an earth leakage detection system of the instrument type (6)
(b) Explain why an insulated neutral system is used extensively on-board ships (2)
(c) State, with reasons, why a single earth fault on an insulated neutral system should always be cleared as soon as possible (2)
Username or email address *Required
Password *Required
Note: Entering wrong username in the login form will ban your IP address immediately. Entering wrong password multiple times will also ban your IP address temporarily.
Log in
Lost your password? Remember me
No account yet?
