Littelfuse, Inc. SE-330 Series – Neutral-Grounding-Resistor Monitor SE-330-21-01

The SE-330 is a neutral-grounding-resistor monitoring relay that detects open or shorted resistors and ground faults as small as 100 mA using DFT filtering to prevent false trips from harmonic noise. It provides two programmable Form C and one Form A output contacts with selectable fail-safe or non-fail-safe modes, an analog 4-20 mA output, and a pulsing output for ground-fault location. The unit includes a mini USB port for configuration and on-board microSD logging. Conformal coating protects internal circuits. Panel or surface mounted, it measures 213 mm high, 98 mm wide, and 132 mm deep. It supports USB and DeviceNet communication and is CSA certified, UL listed, CE marked, and RCM compliant. The SE-330-21-01 variant uses 48 Vdc power, DeviceNet, and a normally closed contact.