Littelfuse, Inc. SE-330 Series – Neutral-Grounding-Resistor Monitor SE-330-07-00

The SE-330 is a neutral-grounding-resistor and ground-fault monitoring relay designed for use with low- and medium-voltage transformers and generators. It measures neutral current, neutral-to-ground voltage, and resistance to detect open or shorted neutral-grounding resistors. The relay features continuous monitoring, harmonic filtering via Discrete Fourier Transform, programmable output contacts (two Form C and one Form A), an analog 4-20 mA output, and onboard event logging. It supports USB communication and optional IEC 61850 with dual RJ45 or SC Fiber interfaces. The unit is conformally coated, operates with a universal current transformer, and is CSA certified, UL Listed, CE marked, and RCM compliant. Mounting is panel or surface, and dimensions are 213 mm H × 98 mm W × 132 mm D. The SE-330-07-00 variant includes IEC 61850 with dual SC Fiber and RJ45 interfaces, as indicated by the ordering code.