Fig. 2,647.—General Electric small plant alternating current switchboard, designed for use in small central stations and isolated plants. They are for use with one set of bus bars, to which all generators and feeders are connected by means of single throw lever switches or circuit breakers, suitable provision being made for the parallel operation of the generators.
Fig. 2,648.—Crouse-Hinds voltmeter and ground detector radial switch, arranged for mounting on the switchboard. The switch proper is placed on the rear of the board with hand wheel, dial, and indicator only on the front side. The current carrying parts are of hard brass, with contact surfaces machined after assembling. The contact parts are of the plunger spring type, and the cross bar has fuse connections. Ground detector circuits are marked G+ and G- for two wire system, and G+, G-, GN+ and GN- for three wire system. When the voltmeter switch is to be used as a ground detector, two circuits are required for a two wire system, and four circuits for a three wire system, that is, a six circuit voltmeter and ground detector switch for use on a two wire system has two circuits for ground detector and four circuits for voltmeter readings. A six circuit voltmeter and ground detector switch, for use on a three wire system, has four circuits for ground detector and two circuits for voltmeter readings.
Switchboard Panels.—The term "panel" means the slab of marble or slate upon which is mounted the switches, and the indicating and controlling devices. There are usually several panels comprising switchboards of moderate or large size, these panels being classified according to the division of the system that they control, as for instance:
1. Generator panel;
2. Feeder panel;
3. Regulator panel, etc.
In construction, the marble or slate should be free from metallic veins, and for pressures above, say, 600 volts, live connections, terminals, etc., should preferably be insulated from the panels by ebonite, mica, or removed from them altogether, as is generally the case with the alternating gear where the switches are of the oil type.