This article describes the design, testing, and commissioning of modified low-voltage switchgear located in a major chemical and refining complex. The intent of the redesign was to significantly reduce the incident energy at the line and bus side of the low-voltage lineups. The company mandated that the incident energy should be reduced to Category 3 (25 cal/cm2 or lower) at the low-voltage line side of the main breakers and to Category 2 (8 cal/cm2 or lower) at the bus or load side of the low-voltage main breakers. To achieve the reduction of incident energy, new relaying schemes used arc-flash sensors and high-speed Ethernet networks with generic object-oriented substation events (GOOSE) messaging to send protection and metering information to upstream relays. This article describes the efforts to modify the equipment, the demonstration tests to show that the protection scheme worked as expected, and the system commissioning.
