Trips, Alarms, Fuses
Explain EACH of the following electrical terms:
(a) preferential tripping;(2)
(b) sequential starting;(2)
(c) fuse back up protection;(2)
(d) discrimination;(2)
(e) non-essential consumer.(2)
Question 8.
Candidates struggle with sequential starting, the reason for back up fuses and discrimination. Most state circuits for propulsion are the only essential circuits.
1.Quiz. Study Notes
Explain how EACH of the following electrical safety devices may be tested for correct operation:
(a) a generator reverse power trip;(2)
(b) generator over-current alarm;(2)
(c) generator over-current trip;(2)
(d) emergency generator auto start up;(2)
(e) preferential tripping sequence(2)
2.Quiz. Study Notes
Explain, with the aid of sketches, how a new motor is aligned with an existing pump.(7)
State THREE checks which should be made before using the pump after the motor has been aligned.(3)
Question 8.
Many do not explain how the alignment is checked – simply stating use dial indicator with a sketch of it in position is not enough. Some, not many, mention shims but none actually explain which shims would be adjusted to change the alignment or that angular misalignment can be in more than one plane.
3.Quiz. Study Notes
(a) Explain how propeller thrust is transmitted to a vessel’s hull.(3)
(b) Describe the mounting arrangements of a thrust block to the hull.(4)
(c) Explain why the clearance between the thrust block pads and collar is critical.(3)
4.Quiz. Study Notes
(a) Describe the operation of a preferential trip.(5)
(b) State the type of circuits that cannot be connected to the preferential trip, listing THREE examples.(5)
5.Quiz. Study Notes