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Protective Relays

Ground Continuity Monitors

  • Description
  • Features
  • Applications
  • Ordering Info
  • Downloads
  • Accessories
  • GM420

    Digital ground continuity relay for AC systems

    The GM420 monitors the ground conductor loop in AC systems. Three types of alarms may be used - a line resistance value (0...100 Ω), an OL alarm (when a very high resistance or break in the loop is detected), and an extraneous voltage between the two monitoring terminals. The loop resistance is displayed on the LCD screen in real-time. Two SPDT contact outputs are included and may be set to any combination of the alarms.

  • Key Features: GM420

    • Ground continuity monitoring in AC systems
    • Alarms for line resistance (0...100 Ω), break in the loop, and extraneous voltage
    • Line resistance displayed in real-time on the digital display
    • Onboard menu for settings; explicit trip values can be entered in
    • Two SPDT contact outputs, independently configurable to any combination of alarm types
    • Separately adjustable time delays for response delay, startup delay, and delay on release
    • Built-in test and reset buttons
    • Latching or non-latching operation, selectable
    • Normally energized or normally de-energized operation, selectable
    • Last triggered alarm value stored in memory
    • Auxiliary supply voltage inputs
  • Applications: GM420

    • General applications requiring ground monitoring
    • Portable equipment
    • Trailer docks and loading areas
    • Motor overvoltage and phase loss protection
  • Ordering information: GM420

    Name0...400 μA analog output0(4)...20 mA analog output0...10 V analog outputSPDT contact outputSupply VoltageOrdering Number
    GM420-D-12AC 16 - 72 V (42 - 460 Hz) DC 9.6 - 94 V B93082001
    GM420-D-22AC 70 - 300 V (42 - 460 Hz) DC 70 - 300 V B93082002
  • Downloads: GM420

    Document Name Language Date Download
    Technical Bulletin / Datasheet
    English 04.2011
    Installation Bulletin
    English 10.2012
    User Manual
    English 09.2007
    Overview of Products
    English 06.2017
    3D STEP Drawing
    420 Series (Standard)
    N/A 06.2013
  • Accessories: GM420