Power resistor packs for dynamic braking are now available in continuous ratings to 4kW from Pentagon Electrical. Intermittent loading on these can be up to 2,000% more than this, the manufacturer claims.

Applications are anywhere that electric motor drives and inverters are subjected to constant stop/start operation. The resistors are designed for use as load banks, for motor starting and for motor braking.

Higher ratings were made possible by the use of vitreous enamelled resistors that can withstand a temperature rise of 380°C. Conventional open wire-wound resistors are less thermally robust.

Housing the resistor elements are powder coated zinc plated perforated steel enclosures available in four sizes.