The increased number of independent power producer (IPP) interconnections for peak shaving and power continuity applications on distribution feeders has increased the interest in, and application of, IPP interconnection protection. When operating IPP generation, known as dispersed generation (DG), is parallel with the utility, the applied interconnection transformer winding arrangement has an effect on what protection is applied to provide utility ground fault detection, and the subsequent separation of the IPP's generator from the utility. This protection and separation of the IPP's DG from the utility is required, so the IPP does not continue to feed into a utility ground fault after the utility has tripped an upstream substation circuit breaker or a line fault-clearing device, such as a recloser. Clearing a utility ground fault from all sources, including any IPPs on the feeder, is necessary to extinguish the arc. A typical circuit is illustrated in Figure 1.
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