Switchboard
(a) State FIVE devices fitted to a main distribution switchboard in order to protect a.c. generators that can be operated in single or parallel mode.
(5)
(b) Explain why EACH device stated is needed.(5)
Question 9.
The question asks about devices for protection of generators, many include pref trip and other devices that are for protection of distribution. Most, when answering about the reason for a device, simply state what it does-i.e over-current protection protects against overcurrent. The question is asking for the reason for the device-i.e what would overcurrent do to the generator.
1.Quiz. Study Notes
(a) Describe, with the aid of a sketch, a cartridge type fuse.(7)
(b) State why a fuse used in a motor circuit differs from a fuse used in a lighting circuit.(3)
2.Quiz. Study Notes
(a) Sketch a line diagram of an emergency switchboard arrangement, labelling the MAIN components.(6)
(b) Explain how main electrical power is restored to the emergency switchboard after a blackout, stating the precautions necessary. (4)
3.Quiz. Study Notes
With reference to shore supplies:
(a) state THREE necessary parameters that must be checked before connecting to the vessel’s distribution system;(3)
(b) explain the possible consequences of connecting an incorrect shore supply.(7)
Question 9.
Several mention the parameters and then totally ignore them in part b. Many state what will occur but not the consequences eg high current but not explaining that this will cause overheating and damage.
4.Quiz. Study Notes
5.Quiz. Study Notes
With reference to the connection of shore power supply on a vessel that does not have a shore power converter:
(a) list the items that would be included on a checklist for supply of power to the vessel;(7)
(b) state the effects of running a 60Hz vessel on a 50Hz supply.(3)