Using a latching relay in energy management also requires a current sensor.
Today four major different current sensing technologies are available:

• Current Transformer
• Hall Sensor based
• Rogowski Coil
• Shunt resistor

GRUNER relays 704, 721, 722 and 741 are available with integrated shunt resistors.A strip of NiCal™ is integrated in one of the load terminals.

Two connections are located close to the resistor on the copper terminal. Thesemust only carry the current Sensor signal. A third connection is reserved for thereference signal of the electronics to avoid RF-sensitivity.

Lamp Load

Another application for latching relays is lamp load switching. Because of high inrush currents, the 707L and 704L relays were specifically designed to meet this requirement.They switch lamp loads up to 4800W or fluorescent lamps with 200 µF parallel compensation circuits. A strong connection between the H- armature and contact spring allows the relay to break micro welded contacts caused by the high inrush currents.

All GRUNER Relays meet the IEC 62053-21 and IEC 62054-11 requirements. In addition relay types 722 and 733 meet Utilisation Category UC3 in accordance with IEC 62055-31.

No semiconductor-based disconnection device is able to withstand the harshoperating conditions such as

• high dielectric strength
• high overload capacity
• high fault currents during switching

without expensive protection.