6.1. Main switchboard and distribution boards
The main switchboard is the main hub distributing power to other parts of the system.
The power is transferred from the generators to the main switchboard through the bus bars which are large pieces of conductor, usually copper. The main bus bar usually has three thick, heavy bars of conductor, running horizontally throughout the length of the main switchboard. The bus bars can withstand high voltages and currents and are located at the bottom of the main switchboard to be supported and insulated easily. The insulation prevents their interaction and is applied wherever the bus bar is clamped or connected to the main switchboard. The bus bars may be divided and connected to each other by either a clamping (sliding device) or circuit breaker.
The rating of the main bus bar is decided by the type of the ship, the necessary machinery on board required for cargo operations, and the machinery required for normal sea service.
The distribution boards are intended to distribute the power to the groups of local users. They usually serve several motors or other electrical devices. Instead of having many cables connecting each motor or other load to the main switchboard, the distribution board allows a single cable to transfer power to the remote area on board. In addition, this layout adds to the stability of the system, as in case of failure the single distribution board is out of order but not a blackout of the whole power distribution system.