Abstract: This chapter discusses the aspects of switchgear maintenance, the current rating of a circuit breaker, fault ratings, air circuit breakers, vacuum circuit breakers, sulphur hexafluoride (SF6) circuit breakers, automatic control of diesel generator sets, and the factors that affect the current rating of busbars. Switchboards on vessels are classified as: (1) main switchboards, to which the main generators are connected; (2) emergency switchboards, to which the emergency generator or battery is connected; (3) section boards, supplied either directly or via transformers from the main or emergency switchboards; (4) distribution boards. With an alternating current (AC) system, the duty of fault interruption is made easier than on direct current (DC). When an AC fault occurs, the fault current, after the first few cycles, would pass through a current zero in every half cycle. The arc that is drawn between the contacts of the opening circuit breaker would have a tendency to extinguish at each current zero. A DC breaker can interrupt the fault current by increasing the resistance of the arc until the latter can no longer maintain it. For a given type of circuit breaker, it is possible to obtain a higher interrupting capacity on alternating current than on direct current.
Publication Year: 1990
Publication Date: 1990-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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