html{display:none} SEL-9501 Contact Arc Suppressor | Schweitzer Engineering Laboratories


Contact Arc Suppressor

Decrease maintenance costs, increase contact reliability/dependability, and reduce destructive dc circuit overvoltages by applying the self-powered SEL-9501 Arc Suppressor to dc circuits.

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Improved Reliability—Eliminate the single largest failure mode of protective relays, and prevent contact welding caused by the inadvertent interruption of the tripping current by relay contacts that are not rated for such high currents.

Breaker Contact Wear Reduction—Eliminate electrical wear in circuit breaker 52a/52b contacts. SEL-9501 Contact Arc Suppressor shunts current around the opening contact. It then interrupts the current and dissipates the energy internally instead of damaging contacts.

All-Inclusive Protection—Protect many other contact types, such as trip, close, lockout coil, auxiliary, and control switches. The SEL-9501 should not be used with reed relays.


  • Increase the existing contact interrupt rating to 10 A @ 160 Vdc for a circuit with a L/R ratio of less than or equal to 40 ms.
  • Installs easily with two-terminal connection: connect the red lead to contact +Vdc, and the black lead to contact -Vdc.
  • Withstands interrupting 10 A of trip coil current four times in three seconds; trip/high-speed reclose/trip/delayed reclose/trip/delayed recloser/trip.
  • Protects many contact types, including 52a, 52b, trip, close, lockout coil, auxiliary, and control switch.
  • Low-cost, two-terminal device.
  • Install in parallel with any dc contact.
  • Connect across auxiliary contacts, lockout switch contacts, trip contacts/close contacts, programmable logic controller (PLC) contacts, sensitive communication contacts, and SCADA contacts.
  • Protects the contact by actually interrupting the current.
  • Increases contact reliability.
  • Reduces contact monitoring.
  • Eliminates contact service and maintenance.
  • Eliminates contact arcing in dc circuits.
  • Eliminates contact wear.
  • Reduces voltage stress with smooth current interruption.
  • Reduces dc circuit "noise."

The Firmware IDs for older versions of the firmware can typically be found in Appendix A of the instruction manual.