NGRM-ENC Series – Enclosed Neutral-Grounding-Resistor Monitor Series - Littelfuse NGRM-ENC Enclosed Resistance-Grounding Monitors Provide Superior Protection

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Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

The NGRM-ENC enclosed neutral-grounding-resistor monitor series is a Type 4X enclosure housing a Littelfuse Startco SE-325 or SE-330 neutral-grounding-resistor monitor and optional accessories, which include:

  • 480–600 V control power transformer (CPT)
  • Faulted-phase indication (FPI; implemented with an EL3100 ground-fault and phase-voltage indicator)
  • Earth-leakage panel meter
  • Pulse-enable control
  • Mounting options
Appropriate fusing is included and field wiring is connected to terminal blocks.


SE-325 Neutral-Grounding-Resistor Monitor
Measures current and voltage in a transformer or generator neutral-to-ground connection and continuity of the neutral-grounding resistor. For applications in Canada, use the SE-330 to meet 2018 CEC 22.1 requirements.

SE-330 Neutral-Grounding-Resistor Monitor
Advanced ground-fault and neutral-grounding-resistor monitoring relay that measures neutral current, neutral-to-ground voltage, and neutral-to-ground resistance.

EL3100 Ground-Fault & Phase-Voltage Indicator
Three panel-mounted LEDs indicate the ground-faulted phase.

Panel Meter
Panel-mounted meter displays earth leakage current as a percentage of the ground-fault-CT-primary rating.

RK-332/RK-302 Remote Indication and Reset
Panel-mounted remote indication and reset assemblies are included with SE-325 and surface-mounted SE-330 configurations.

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