A major benefit of S&C’s IntelliRupter PulseCloser — PulseClosing Technology — was recently demonstrated at Murfreesboro Electric Department, the electric utility serving customers in Murfreesboro, Tennessee.

In July, an IntelliRupter on the department's system tripped upon sensing a 2700-A phase-to-phase fault. After a 0.3-second delay, the IntelliRupter then pulseclosed to verify that the line was clear of faults before initiating a closing operation. Fault current was indeed still detected on one phase . . . so IntelliRupter did not close.

By contrast, a conventional recloser would have closed in this instance. The substation transformer, conductor splices, and other equipment would have been subjected to damaging fault current until the recloser decided to open again. And upstream customers would have been subjected to another irritating voltage sag in the interim. The consequences would have been magnified if multiple reclosing attempts were necessary.

After a 15-second delay, IntelliRupter again pulseclosed. But no fault current was detected this time, so IntelliRupter closed, restoring service to downstream customers.

Pulseclosing reduces the wear and tear on power system equipment by saving it from the repeated stress of fault current. It extends the life of costly assets, helping to defer the need for replacement equipment. By cutting let-through energy, pulseclosing greatly reduces the risk of fire in dry areas too.

IntelliRupter is fully compatible with S&C’s IntelliTEAM II Automatic Restoration System. This self-healing, scalable feeder reconfiguration system is a universal Smart Grid solution.

Nine-channel waveform captured by IntelliRupter, showing 2700-ampere phase-to-phase fault that triggered tripping. After a 0.3-second open interval, pulseclosing still detected fault current, so closing was not initiated. After an additional 15-second delay, pulseclosing detected no fault current, so closing was initiated, restoring service downstream. Source-side voltage — shown in the middle three waveforms — was virtually unaffected by pulseclosing.