New feeder automation scheme using VIT reclosers and VIT sectionalizers

Traditionally, a coordination scheme of circuit breakers (CBs), reclosers, and sectionalizers using time current curves has been widely used for radial networks with a single supply site or loop networks with two distribution feeders tied by a normally open tie recloser. However, conventional schemes that rely only on current information reclose onto a fault. This major drawback occurs when a normally open tie recloser closes onto the other supply of the system because the load side recloser closest to the fault location is not able to locate the fault condition. This paper proposes a new circuit breaker, recloser, and sectionalizer coordination scheme, referred to as the voltage, current, and time (VIT) scheme. Integral parts of the VIT scheme are strategically applied counters and timers on the protection devices. The VIT protection devices can detect a fault condition from both upstream and downstream of a fault location and assist in isolating only the faulted part of the circuit.