Braking resistor for Altivar drives — now obsolete
The Schneider VW3A68703 is an 8 Ohm braking resistor in an IP30 enclosure, rated for 400V systems in the Altivar drive family. Its job is to dissipate regenerative energy from a decelerating motor as heat, preventing DC bus overvoltage trips on the drive.
The 8 Ohm value determines the braking torque the resistor can absorb — lower ohms draw more current and produce stronger braking, but the drive's internal chopper transistor must be rated for that peak current. The 400V rating matches the DC bus voltage of a 400V-class Altivar drive (typically around 565 VDC). The IP30 enclosure means it is suited for cabinet mounting where no washdown or dust ingress protection is needed; it is not rated for outdoor or wet-area placement. Thermal protection is handled externally — the drive or a separate temperature control switch must monitor the resistor temperature and interrupt the circuit if it overheats. There is no internal thermal cutout in the resistor itself.