Braking power and duty cycle — peak vs continuous
The VW3A7208: Rated for 135 kW maximum braking power and 38 kW permanent braking power at 400 V nominal (380-415 V supply window). The peak figure handles short-duration deceleration events; the continuous figure governs the resistor's thermal steady-state — size the external braking resistor for the duty cycle, not the peak. Overload protection is set at 1.2 times the maximum current, which means the unit will trip if the braking demand exceeds the 135 kW peak for longer than the internal thermal time constant allows.
Installation constraints — altitude, enclosure, and upstream protection
IP20 rated — the unit is not sealed against dust ingress or washdown; it must be mounted inside a panel or cabinet that provides the environmental seal. The 245 mm width, 242 mm depth, and 700 mm height require a backplate or DIN-rail area that accommodates the full footprint with clearance for cable entry and airflow. Operates at altitudes from 1000 m to 4000 m with a current derating of 5 % per 1000 m above sea level. At 3000 m, derate the continuous braking power by 10 % from the 38 kW figure. Below 1000 m no derating applies. Requires an associated fuse rated 315 A at 660 V on the supply side — this is the upstream short-circuit protection, not the unit's internal protection. The fuse must be coordinated with the braking resistor and drive input to clear faults before the unit's IGBTs exceed their SOA.
Lifecycle status and sourcing reality
Marked obsolete by Schneider Electric. The unit is available through independent surplus and broker channels; quantities are lot-specific and confirmed at RFQ. No pin-compatible or functional drop-in replacement from the same brand has been published. Storage temperature range is -25 to 55 °C — the unit can be held in inventory for spares without climate-controlled storage, but the electrolytic capacitors in the DC bus will age faster at the upper end of the range.
Efficiency and power factor — thermal impact in the cabinet
97 % efficiency and unity power factor (cos phi = 1) mean the unit dissipates roughly 3 % of the braking power as heat inside the enclosure. At 38 kW continuous braking, that is about 1.14 kW of heat that must be removed by cabinet ventilation or forced air — factor this into the enclosure thermal design.