Littelfuse, Inc. SE-325 Series – Neutral-Grounding-Resistor Monitor SE-325ST

The SE-325 series is a neutral-grounding-resistor monitor for resistance-grounded systems up to 25 kV, designed to detect NGR failures and ground faults by measuring current and voltage in the neutral-to-ground path. It features a Form A output contact, adjustable ground-fault trip levels from 0.5 to 4.0 A, and adjustable trip delays from 0.1 to 2.0 s. The device supports selectable fail-safe or non-fail-safe operating modes, includes a standard reset button, and is conformally coated. It operates on 120 V ac, 120 V dc, or 240 V ac, and is housed in a case measuring 150 mm high, 109 mm wide, and 100 mm deep. The unit is CSA certified, UL Listed (E340889), and complies with C-Tick standards. A CT200 current transformer and ER series sensing resistor are required for proper operation.