Hilkar Metal Enclosed RC Snubber filters protect electrical machines from damage caused by insulation failures which occur in the windings of equipment such as generators, reactors, motors and transformers. Unless certain protection measures are taken into consideration, significant losses can be incurred. During the turn-off action of the breaker or contactor, considerably large over-voltages can occur due to the sudden interruption of an inductive current. In order to prevent any damage to system equipment, high frequency transient over-voltage surge suppressors, also called RC snubber filters are used. Most often they are used in conjunction with shunt reactors or other inductive loads to provide protection for motors, transformers and generators from things such as: steep wave-front, short time rise, high magnitude, spikes, surges, transient over-voltages and circuit switching. By clamping the voltage overshoot due to the current interruption, they are thus able to safely damp out the oscillations.


  • Save on cost, via reduced downtime and repair costs
  • Improve operational performances, as a result of reduction in production downtime
  • Superior protection against interturn insulation failures
  • Extended lifetime of motors/transformers
  • Reduce the likelihood of pre-strike, re-strike, and re-ignition observed at circuit breakers
  • Reduce the magnitude and rate of rise of voltage (RRRV) transients
  • Ease of installation


Application Areas
  • Power Generation
  • Pulp and Paper Industry
  • Petrochemical Industry
  • Chemical Factories
  • Surface and Underground Mining
  • Water and Oil Pumping Stations
  • Railway Applications
  • Large Motors
  • Arc furnaces
  • and many other facilities using any kind of motors and/or transformers


Protections Provided
  • Protection against all practical surge peaks and rise-times
  • Withstands all the motor impulse voltage levels recommended by both CIGRE and IEEE
  • Eliminating and damping of multiple pre/re-strike transients which occur during switchgear operation,
  • Eliminates voltage doubling effects by cancelling refraction of surges by providing a matched cable terminating impedance and thus halving the magnitude of the surge
  • Eliminates higher harmonic current zeros through the breakers by disabling current reflection waveforms


Product Range
  • Operating Voltage: Up to 36kV
  • Compact size, up to 36 kV networks, all components (R+C+LA) are contained in single case
  • Impulse Withstand Voltage: Up to 200kV BIL
  • Variety of surge capacitance ratings depending on the site requirements and application type (ie, 0.1-2 µF)
  • Variety of surge resistance ratings depending on the site requirements and application (ie, 1-200 ?)
  • Fully assembled, tested, and ready for interconnection



A typical comparison of RC snubber protection is provided below, where for CASE-A no protection is active in the network and for CASE-B a RC snubber coupled with a surge arrester is used for transient voltage waveform steepness and peak reduction while ensuring defined withstand voltage limits are not violated.

CASE-A: No RC protection during switching

CASE-A: No RC protection during switching

CASE-B: With RC protection during switching

CASE-B: With RC protection during switching

Types Available

RC snubbers are available as custom designs between 1 to 36 kV as single or three phase 50/60Hz systems, mainly for industrial motor & transformer, reactor and generator protection applications. Single phase and three phase RC Snubbers are manufactured by HİLKAR are custom built to meet your requirements. Basically, they are composed of a combination of capacitors, resistors and surge arresters to reduce the magnitude and frequency of transient voltages observed. For requests for lower or higher system voltages please contact factory.


Installation & Commissioning

    Hilkar RC Snubbers are suitable for (but not limited to) being installed at the following connection points depending on the application:

  • - In the protected equipment’s terminal box or associated switch panel, between each phase to ground.
  • - Connected to the equipment terminal box via a minimum of 3x25/16 mm2 cable with the provided accessories.
  • - RC Snubbers must be grounded to the motor/transformer ground or the breaker earth connection.
  • - When porcelain bushings are used, connections to the bushings must be through flexible connections, so that any shock or vibration that may be transmitted to the bushing during transportation or in service, does not cause any damage.
  • - The fixing nuts shall not be tighter than 20Nm.
  • - The flexible leads can be shortened but cannot be extended and must be directly connected to the protected equipment terminals.