R.C. Snubbers

An R.C. snubber is a protective circuit consisting of a resistor and capacitor connected in series and installed across transformer or reactor windings. Its purpose is to absorb and dampen voltage transients caused by switching events or circuit interruptions. By limiting the rate of voltage rise (dV/dt), it prevents insulation stress and reduces electrical noise. Rex Power Magnetics R.C. snubbers extend transformer life and improve system reliability in applications where frequent switching or pulsed loads occur.

Ideally, an RC snubber should be installed as close as possible to the transformer it is designed to protect. For new transformers, if space allows, the snubber can be integrated directly within the transformer enclosure, ensuring a minimal cable length between the snubber and the transformer. In retrofit applications or when a standalone snubber is required, careful attention should be given to minimizing the cable length between the transformer and the snubber to ensure optimal protection.

Since power systems are dynamic and each setup varies, there is no universal recommendation for the maximum acceptable cable length before the snubber’s effectiveness is compromised. A thorough analysis, including Transient Recovery Voltage (TRV) studies, is necessary to assess system-specific parameters and determine how the cable length between the RC snubber and the transformer will affect its performance.

Power systems are inherently dynamic, and each setup differs in terms of load characteristics, equipment ratings, manufacturer specifications, configurations, insulation levels, voltage ranges, and the interconnection of various components.

While standard benchmarks and guidelines exist for designing snubbers, a thorough analysis and Transient Recovery Voltage (TRV) studies are necessary to accurately predict the unique transient voltage levels and frequencies specific to each system. This is due to the fact that no two power systems are exactly alike.

By using the results from TRV studies, the ideal capacitor and resistor values can be sized to enhance the system’s protection.

R.C. snubbers are used in medium-voltage and industrial systems where transformers, reactors, or contactors experience frequent switching or high transient currents. Typical applications include capacitor banks, motor control centers, filter circuits, and power-factor correction systems. They are also installed on line/load reactors for variable frequency drive (VFD) systems to limit switching transients and improve insulation endurance.

When a transformer or reactor is de-energized, its inductive energy can generate a high-voltage spike across the terminals. The R.C. snubber absorbs this energy and dissipates it as heat through the resistor while the capacitor limits the instantaneous voltage rise. This prevents voltage overshoot that can damage insulation, cause partial discharge, or prematurely age components. Properly sized snubbers also reduce electromagnetic interference and switching noise in adjacent equipment.

Yes. Rex Power Magnetics designs custom R.C. snubber assemblies to match equipment ratings and transient energy levels. Custom options include resistance and capacitance values, voltage ratings, mounting dimensions, and connection methods. Engineering teams use system transient analysis data to design optimized snubbers for maximum protection and efficiency. Each custom unit is built and tested to the same rigorous standards as catalog models.