1M123 High Impedance BUS Protection Rack


High impedance protection schemes are widely used for the protection of BUS bars, generators, motors & power transformers. BUS bar protection schemes utilizing electromechanical high impedance differential relays are often used due to their simplicity, reliability & comparatively low cost. While numeric high impedance differential relays are now available the application of electro mechanical schemes is likely to continue at least in the role of the Y protection scheme where duplicate protection is employed. The 1M123 system is an integrated protection scheme which overcomes the issue of space constraints on the protection panel & the problem of where & how to mount the Metrosil elements. The provision of at least one high speed multi trip relay is normally required and often a trip supply supervision element. All of these functions have been incorporated into a single tier, 4U high, 19 inch sub rack frame.


  • Compact single tier BUS bar protection system
  • Proven electro mechanical high impedance differential scheme
  • Integrated 3 Phase Metrosils
  • Integrated multi trip relay
  • Optional trip supply supervision
  • Pre assembled & wired in 4U high 19” sub rack
  • High speed operation
  • High sensitivity
  • Wide range of settings
  • High stability
  • Made in Australia



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