In the first part of this series, featured in the February 2011 issue, we considered the selection of the protective devices of a low-voltage induction motor supplied from a motor control center (MCC) ...

Compliance with NEC 110.10 is critical for safety. We all want safe designs, but the engineer responsible for a UPS installation may not always understand how to accommodate the UL listing unique to ...

High speed, high current interrupting devices are interrupting devices that have extremely short opening times and are current limiting; that is, they limit the amount of bolted fault current that can ...

One of the major challenges facing the electric industry is how to manage network fault levels, the magnitude of the electrical current that flows into a fault or short circuit. These current levels ...

A bolted short circuit occurs in the series R-L circuit of the given figure with V = 30 kV, X = 10Ω , R = 0.9Ω, and with maximum dc offset. The circuit breaker opens 3 cycles after fault inception.