Product Summary

The GRT508FN is a 3-pole latching relay built for smart metering circuits. Three sets of AgSnO2 contacts switch up to 120A resistive load at a maximum switching voltage of 250VAC, so one relay covers three circuits inside a meter. The coil only needs an impulse to change state — both single coil and double coil versions hold their position after the pulse ends, which means no continuous coil current in the finished meter.

A 4KV dielectric strength between coil and contacts separates the control side from the load side, and the relay withstands 3000A/10ms and 6000A/10ms short-circuit current without explosion. The unit is IEC62052-31 UC2 and UC3 compliant and RoHS compliant, with an outline of 98.2 × 40.3 × 37.7 mm.

Key Features

Technical Specifications

Models and Options

• GRT508FN — the 3-pole, 3 × 120A base configuration with fast connection installation.
• Coil voltage — selectable anywhere in the 5–24 VDC range to match the meter drive circuit.
• Coil type — single coil or double coil, both operating on impulse excitation only.
• Custom assemblies — available with flexible wire and/or copper straps, and/or with integrated shunt.

Materials and Structure

The relay is built on a copper and plastic construction. The three contact sets use AgSnO2 contact material, chosen for resistive load switching at 120A. Contacts, coil and terminal block sit inside a housing measuring 98.2 × 40.3 × 37.7 mm, with fast connection terminals for the load side and a coil interface driven by impulse. Because the mechanism latches mechanically after each pulse, the contact position is maintained without holding power. Mechanical endurance is rated at 100,000 operations, and electrical endurance at 10,000 operations for 100A 230VAC or 6,000 operations for 120A 230VAC.

Applications

The GRT508FN is designed for the smart metering industry, where it performs on-off control of energy meter circuits and stays latched after switching so the meter draws no continuous coil power.

• Smart electricity meters — pulse-driven switching inside the meter, matched with the energy measurement module.
• Prepaid meters — latching contact state supports connect and disconnect control of the load circuit.
• Smart home control units — three-contact switching where state must survive power interruption.
• Operating environment — ambient temperature -40°C to +85°C, relative humidity 5%–85%RH non-condensing, altitude up to 2000 m, no corrosive gas or explosive dust in the surroundings, resistive load.

Customization

Custom assemblies are available with flexible wire and/or copper straps, and/or with an integrated shunt, so the relay can be matched to a specific meter terminal layout. Coil voltage can be specified within the 5–24 VDC range, and coil type can be single or double. Discuss your terminal arrangement, wiring length and shunt requirement with the engineering team when requesting a quotation.

FAQ

Inquiry Information

Zhejiang Great Electrical Co., Ltd. was founded in 2003, operates a 50,000 m² factory with 500 employees and a 60-engineer R&D team, and exports 55% of its output, mainly to the EU and India.

Image Filename and Alt Suggestions

• latching-relay-grt508fn-3x120a-front-terminals.png — GRT508FN 120A latching relay front view with three contact sets and fast connection terminals
• latching-relay-grt508fn-terminal-side-copper.png — terminal side view of the GRT508FN relay showing copper conductor and plastic housing
• latching-relay-grt508fn-outline-dimensions.png — GRT508FN relay positioned to show the 98.2 x 40.3 x 37.7 mm outline
• latching-relay-grt508fn-coil-interface.png — coil interface side of the GRT508FN impulse-driven latching relay