PGR-3100 Series – Ground-Fault Relay Series - Littelfuse PGR-3100 Relays Provide Superior Ground-Fault Protection

External overview image
Roll Over to Zoom
Disclaimer Notice

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 PGR-3100 series ground-fault indication system operates on ungrounded ac systems. This unit indicates the presence of voltage on each phase of a three-phase system. The LEDs on the panel illuminate when voltage is present. When a ground-fault occurs, the voltage on the faulted phase reduces to ground potential causing the LEDs for the faulted phase to dim. On a resistance grounded or ungrounded system, the LEDs for the unfaulted phases become brighter. Ungrounded ac systems are required by NEC Article 250.21(B) and Canadian Electrical Code (CEC) Part 1, Section 10-106 (2) to have ground detectors (such as the PGR-3100) installed on the system. External potential transformers (PTs) can be used to step down system voltage, allowing the PGR-3100 to be applied to any system voltage. PTs are not required for system voltages up to 600 V ac.


  • NEC® and CEC code compliant
  • Phase LEDs
  • Redundant LEDs
  • Lamp test button
  • POWR-GARD® technology

Access specifications, certifications, check availability and order parts below

Catalog #Supply
Relay Contacts ConfigIEEE Device NumbersWeight (lbs/g)Conformally coatedSystem typeSamples
PGR-3100600N/AN/A27 - 640 KgOptionalUngrounded DCOrder
To request product environmental information, please complete the Product Environmental Information Request Form.