These transient voltage surge suppressors are designed to clamp high voltage pulses occurring on a 250 VDC bus to a predictable level in order to protect down-stream electronics. The primary source of this transient energy occurs when turning off inductive loads such as DC lifting magnets. The magnitude can be a few thousand volts for milliseconds. The primary component used is a Selenium Surge Suppressor housed in a steel, wall mounted NEMA 13 cabinet.