The VW3A7103 is a resistance braking unit rated for 300 kW permanent braking power at 690 V, with a maximum braking capacity of 450 kW. It is designed for use with variable speed drives to dissipate regenerative energy from decelerating motors, typically on high-inertia loads like centrifuges, conveyors, or large fans. The unit activates at a DC bus threshold of 1075 V DC (±1 %) and can handle a maximum DC bus voltage of 1100 V. The minimum external resistor value to associate is 2 Ohm. Thermal losses are 650 W, requiring 600 m³/h of cooling air. Operating ambient temperature range is -10 to 50 °C, storage -25 to 70 °C. Pollution degree 2 per EN 50178 (non-conductive pollution only). Mount vertically only.
Load factor and braking power profile
The unit supports three load-factor / engage-threshold settings: 0.05 for 450 kW at constant power, 0.15 for 400 kW, and 0.5 for 350 kW. These define the duty cycle — a lower load factor allows higher peak power but for a shorter duration. The permanent rating of 300 kW at 690 V is the continuous dissipation limit.