Crowbar resistors are used to protect the outputs of power sources in railway systems against the short-time (transient) and long-time overvoltage failures.

Output voltage rises very fast (in microseconds) when semi-conductors of power source fail (short circuit) or the control circuit collapses. Protection system fully independent from the control system of power source detects the fast increase of the output voltage and switches the crowbar resistor connected to the power output with the semi-conductor switching system. In this case, crowbar resistor create an over current limited to a value that will not damage the power supply but will activate the protection equipment such as fuses and circuit breakers and attenuate the over voltages very quickly.

Technical Specifications:

  • Stainless steel resistance material suitable for extreme ambient conditions, resistant to oxidation and corrosion, low resistance variation against to temperature
  • Special vibration proof mechanical and electrical design to withstand high temperature and inrush current
  • Design and tests in accordance with IEC 60071-1 and other special specifications

Resistor Element:

  • Spring-wound, edge-wound or grid resistor elements with a cross-section suitable for the nominal current
  • Fully modular, bended and stainless steel bolt connections in order to ensure electrical continuity at high temperature
  • High conductivity for high current with bended and cascaded terminal connectors suitable for serial and/or parallel connections with high cross-section, low contact resistance
  • High internal insulation and high mechanical resistance against to shocks and sagging thanks to the use of large surface satiated bushings and M16 shear connectors
  • Special designed to dissipate the thermal and mechanical effects of overcurrent to the surface grid resistors


  • Special sizing to fit the location of use, suitable for outdoor or indoor usage and perfect cooling
  • Corrosion-resistant handling system and connectors
  • Stainless steel product and warning labels


  • Requested protection level from IP00 to IP55
  • Hot-dipped galvanized, stainless steel, aluminum enclosure
  • Painting enclosure in desired color code