Q1. (a) Compare methods of obtaining speed regulation of three-phase induction motor generally used in tankers by means of: (16) i. Rotor resistance. ii. Cascade system. iii. Pole-changing.
Give examples where each system may be employed with advantage.
Q2. With reference to a 3 speed a.c. cage motor driven cargo winch:
a) Sketch a circuit diagram for a pole change motor. (8)
b) Describe how speed change and braking are achieved. (8)
Q3. With reference to preferential tripping in a marine electrical distribution system. a) With the aid of a sketch, describe a typical arrangement to provide three stages of tripping an instantaneous protection against short circuit. (10) b) State why this protection is required. (6)
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?
