Protection Relays & Controls SE-330AU SERIES Neutral-Earthing-Resistor Monitor Description The SE-330AU is an advanced earth-fault and earthing-resistor monitoring relay for low- and medium-voltage transformers and generators, compliant to AS/NZS 2081.6:2011 and AS/ NZS 2081.8:2011. It monitors neutral current, neutral-to-earth voltage, and neutral-to-earth resistance. It provides continuous monitoring of the neutral-to-earth path to verify that the neutral-earthing resistor (NER) is intact. This is of utmost importance— an open NER renders current-sensing earth-fault protection inoperative and could result in a false belief that the system is functioning properly. Outputs include four relay outputs, and an analog output. A mini USB port is included to view measured values, configure settings, and check event records. An on-board micro SD card can be used for long-term data logging. Network communications options are available. For non-AS/NZS 2081 applications, see the SE-330 or SE330HV. Resistor Monitoring Simplified Circuit Diagram The SE-330AU combines the measured values of resistance, current, and voltage to continuously determine that the NER is intact. It is able to detect a resistor failure with or without an earth fault present. Sensing resistors are matched to the system voltage and are used to monitor NGRs on systems up to 35 kV. Earth-Fault Monitoring The SE-330AU uses a 5- or 30-A-primary current transformer to provide a pickup-setting range of 0.125 to 5 A or 0.75 to 30 A. DFT filtering ensures that false trips due to harmonic noise from adjustable-speed drives do not occur. Open-CT detection is provided. Specifications Input Voltage Dimensions GF Trip-Level Settings GF Trip-Time Settings Vn Trip-Level Settings Output Contacts Operating Mode Harmonic Filtering Reset Approvals Communications Analog Output Conformal Coating Warranty Mounting See ordering information H 213 mm (8.4”), W 98 mm (3.9”), D 132 mm (5.2”) 0.125 to 30 A 0.1 to 0.5 s 20-2,000 Vac (≤5 kV systems) 100-10,000 Vac (>5 kV systems) Two Form A, Two Form C Fail-Safe Standard feature Front panel push button and remote input RCM (Australian), CE Mini USB (standard); DeviceNet (optional), IEC 61850 (optional), Modbus TCP and EtherNet/IP (optional) 4-20 mA, self or loop powered Standard feature 5 years Panel, Surface (optional)

Ordering Information ORDERING ER Series Sensing Resistor Required interface between the power system and the SE-330AU. Eliminates hazardous voltage levels at the relay. ACCESSORIES REQUIREMENT Disclaimer Notice - Information furnished is believed to be accurate and reliable. However, users should independently evaluate the suitability of and test each product selected for their own applications. Littelfuse products are not designed for, and may not be used in, all applications. Read complete Disclaimer Notice at www.littelfuse.com/product-disclaimer.