Overview

The IRMS system allows configurable resistance thresholds that determine when a warning or alarm is generated. Proper threshold configuration ensures early detection of insulation degradation, avoidance of nuisance alarms, and reliable system monitoring. Threshold values must reflect installation conditions and maintenance policy.

Understanding Threshold Levels

Two primary levels are available: Warning Threshold generates a warning when insulation resistance drops below this value and does not necessarily disable CCR operation. Alarm Threshold generates a fault condition when resistance drops below this value and may disable output depending on configuration. The alarm threshold is typically set lower than the warning threshold.

When to Adjust Thresholds

Adjustment may be necessary when commissioning a new installation, establishing a baseline resistance value, environmental conditions influence readings, nuisance warnings occur, or maintenance standards change. Do not arbitrarily increase thresholds to suppress valid warnings.

Configuration Procedure

Power the CCR. Press CONFIG. Enter password 9999. Navigate to IRMS or Megger settings. Locate Warning Threshold setting. Enter desired resistance value. Locate Alarm Threshold setting. Enter desired resistance value. Save configuration and exit menu.

Setting Appropriate Values

Thresholds should be based on historical baseline insulation resistance, manufacturer or site maintenance standards, and environmental conditions. If baseline resistance is known, set warning threshold above alarm threshold. Ensure alarm threshold reflects unacceptable insulation condition. Trending historical values improves accuracy.

After Adjusting Thresholds

After updating values, verify settings are saved. Monitor IRMS readings. Confirm warnings and alarms trigger appropriately. Document new threshold settings for maintenance records.

Troubleshooting Threshold Issues

If alarms occur unexpectedly, compare current resistance reading to historical values. Inspect field circuit for moisture or damage. Verify threshold settings are appropriate. If alarms never occur despite known issues, confirm thresholds are not set too low. Verify IRMS is enabled.

Safety Reminder

Adjusting IRMS thresholds does not correct insulation faults. Investigate and correct the root cause of low insulation resistance before returning the CCR to service.

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