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CM-IWx Insulation Monitoring Relays

Reliable insulation monitoring of IT systems

The CM-IWx insulation monitoring relays guarantee the continuous insulation monitoring of IT systems thus minimizing downtimes of your installation.

ABB’s CM-IWx insulation monitoring relays for IT systems provide continuous, reliable monitoring. The devices recognize insulation faults as they develop, tripping as soon as the value falls below minimum set thresholds. This makes systems more reliable and prevents interruptions caused by severe secondary insulation faults. Make your monitoring more secure and your maintenance smarter with CM-IWx insulation monitoring relays.

Continuous Operation

  • Reduced downtime with early pre-warnings
  • More time for planned maintenance
  • Early fault detection with monitoring of voltage-free networks
  • Variants with rail and ship approvals available

Safety & Protection

  • Safe and reliable insulation fault detection
  • Compliance with latest standards
  • Solutions for standard and challenging applications
  • Fast, reliable earth fault detection supports fire prevention
  • Self-diagnosis and interrupted wire detection

Easy Installation

  • Clear visualization of device status via LEDs
  • Easy adjustments with rotary wheels
  • Push-in terminals


  • System voltage monitoring up to 1500 V DC and 1100 V AC
  • System leakage capacitance monitoring up to 3000 µF
  • Versatile system monitoring for 2-wire, 3-wire, 4-wire, and battery systems
  • Easy-to-configure interrupted wire detection
  • Easy-to-configure non-volatile fault storage