Modern electric distribution system for an oil refinery

TWO PRIME CONSIDERATIONS in any refinery electric system should be flexibility and dependability. These factors entered markedly into the selection and design of the distribution system which consists of a primary selective combined with a secondary selective system, see Figure 1. The common secondary tie is an aerial loop which is sectionalized by means of pole-mounted switches, normally open. The loop serves the twofold purpose of a secondary tie, when needed, as well as a wide-area distribution feeder covering several miles with numerous loads tapped off, somewhat on the order of a public utility system serving a populated area. The other secondary feeders out of the substations are underground cables direct to points of usage.