In the case of a high pressure alternating current plant of considerable size, the bus bars oil switches, and the current and pressure transformers are generally mounted either in stoneware cells, or built on a framework in a space guarded by expanded metal walls, and no high pressure apparatus of any sort is brought on to the panels themselves.
Figs. 2,659 to 2,666.—Diagram of connections for three phase feeder panels. Key to symbols: A, ammeter; A.S., three way ammeter switch; B.A.S., bell alarm switch; C.T., current transformer; F, fuse; O.S., oil switch; P.I.W., polyphase indicating wattmeter; P.W.M., polyphase watthour meter; T.B., terminal board; T.C., trip coils for oil switch.
Feeder Panel.—The indicating and control apparatus for a feeder circuit is assembled on a panel called the feeder panel.
The most common equipment in the case of a direct current feeder panel comprises an ammeter, a double pole switch, and double pole fuses or instead of the fuses, a circuit breaker on one or both poles; in the case of a traction feeder a choke coil and a lightning arrester are often added.
Figs. 2,667 and 2,668.—Diagrams of connections for two phase and three phase installations: A and A1, ammeter; C.C., constant current transformer; C.T., current transformer; D.R., discharge resistance; F, fuse; F.S., field switch; L.A., lightning arrester; O.S., oil switch; P.P., pressure plug; P.R., pressure receptacle; P.T., pressure transformer; S and S1, plug switches; T.C., oil switch trip coil; V, voltmeter.