From the main bus bar, the electrical power is supplied to various ship board auxiliaries like pumps, blowers, compressors, etc. are connected to circuit breaker such that the faulty generator is electrically isolated from the main bus bar. Various protection for the generators like overload, reverse power, etc. A ship may contain two or more generators connected to the main bus bar via the circuit breaker. Thus the main bus bars are contained within the switchboard feeding various ship board auxiliaries. The main switchboard is the main power distribution center of the ship. At times, there may be two divisions of the bus bar which are connected to each other by either a circuit breaker or a clamping (sliding contact) device. The bus bar lies at the bottom most portion of the switchboard such that it can be easily supported and insulated. Each of the conductors is insulated between each other and wherever it is supported or clamped to the switchboard. The main bus bar has three heavy, thick bars of conductor (usually copper), running horizontally throughout the length of the main switch board. Ship Type - Power RequirementĪ 10,000 dwt general cargo ship-–1 MW.Ĭontainerships (10000 TEU) (3.3kV)-–8 MWĪ Modern LNG carrier (Q-max/Q-flex) (6.6kV)-12 MW If the propulsion is by electric motors, then the vessel might require huge diesel driven generators which usually operate at 6.6kV. If a ship is steam propelled, it might have steam turbine driven alternators and a diesel driven alternator as a back-up. The rating of the main bus bar is decided by the type of ship, the critical machinery on board required for cargo operations, and the machinery required for normal sea service. Onboard a merchant ship, the supply is usually 440 volts, 60 Hertz, however higher voltages of 6.6kV are possible on LNG tankers, special purpose ships, and passenger vessels having electrical propulsion. The main bus bar can be found inside the main switch board. In this article, the general layout of the main electrical distribution system, along with the main switchboard and emergency switchboard arrangements, will be discussed. Unlike a shore based transmission system, where the lengths of the conductors run throughout a country, a shipboard electrical distribution system is short and simple. Electricity has to be distributed with minimal losses after generation.
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