Secondary distribution cabinet for aeroplane's electric power system, comprises multi-layer printed circuit board, with circuit-breakers controlling each outgoing circuit

摘要

The power system is based on a primary control point in the pilot's cockpit, from which feeder circuits (22) run to secondary cabinets (14) distributed through the aircraft, each controlling a gorup of 4 or more utilisation points via secondary feeder circuits all emanating from a plug connector (46) on the cabinet's printed circuit board (30). Each such outgoing circuit is protected by a circuit-breaker (36,38,40,...) rated between 1 and 15 A, fixed mechanically by tags (82) to the board, with its reset button (36C, etc.) projecting through the cabinet's front-plate (50). As well as the power connections (36A,36B, etc.) to the incoming supply track and the outgoing circuit, each circuit-breaker has on/off indicating contacts connected (36D, etc., 54) to tracks leading to a control circuit board (52) parallel with the main board and equipped with a plug connector (56) having a cabled connection to a consolidating display panel in the cockpit. The printed circuit board has, typically, 6 layers, carrying on one the incoming power tracks, over two layers allotted to the outgoing circuit connections, and two for the state monitoring connections. The lowest layer functions as a heat sink. Each upper layer is perforated where necessary to allow conductor access to those below.