Nuclear Power Plant Electrical Switchgear Systems

Turbine Building - Electrical Switchgear

The large panel below shows a typical electrical switchgear. Gauges provide the operator such information as voltage and current levels. Controls are often provided. Panels may be color-coded to alert personnel as to power source for the breakers or different functions of the equipment.

Photo by J.A. Gonyeau

Breakers typically have relays which will cause the breaker to trip open to prevent equipment (motor, fan, or pump) damage due to low voltage, high current, or low frequency conditions. In many power plants, equipment operate at 480 or 600 volts.

In the United States, the alternating current frequency is 60 cycles per second (Hertz). In most of the rest of the world, 50 cycles per second is used. The frequency generated depends on the rotating speed of the turbine-generator and the number of electrical poles of the generator. Thus, in the U.S., turbine-generators rotate at 1800 or 3600 rpm; in the rest of the world, they rotate at 1500 or 3000 rpm.