A braking chopper or chopper is connected to a DC link. When a set brake voltage threshold is reached it switches an internal or external resistor (depending on the series) in a clocked mode. Thus the chopper effectively limits the voltage in e.g. a DC link. Typically, a braking chopper is used with a frequency inverter for demanding braking tasks (up to continuous braking) or to protect regenerative frequency inverters in the event of a mains failure.