The VLT Brake Resistors series serves a specific purpose in drive systems: converting excess braking energy into heat to avoid DC-link voltage surges.
When a motor slows, the kinetic energy returning to the drive must be managed, and these resistors provide a stable, predictable method for handling that load. Construction types within the series differ to match operational demands. Aluminum flat-pack units, suitable for vertical or horizontal mounting, can handle pulse loads as high as 40 times their nominal rating. Compact aluminum versions push this further to around 60×, with housing options in IP 21, IP 54, or IP 65 for varied environmental conditions. Steel-grid resistors, typically chosen for applications with frequent or heavy braking—such as hoists or cranes—are rated to IP 20 and offer robust thermal performance. Installation flexibility is a key part of the design. These resistors can be fixed to a wall, mounted on a floor plate, or positioned behind a drive using footprint brackets. L-profile brackets are also available where space or alignment needs dictate. Orientation can be adjusted to suit heat dissipation requirements. Thermal protection is built in via a galvanically isolated overtemperature switch (PELV), which interrupts operation or signals the drive controller if internal temperatures exceed safe limits. Continuous operation is possible in environments up to 40 °C, with a derating curve that tapers power handling as ambient temperatures approach 70 °C.
