Earth leakage relays offer non-invasive protection

13 August 2010

The EFR-4 EFR-5 earth leakage protection relay from FDB Electrical can be specified for a wide range of trip levels and response times. It is designed for medium to high current applications where space is a limitation, and is housed in a compact DIN-rail mounting enclosure, complete with integral 28 or 46mm CT sensory coil, test and reset buttons and LED status indication.

The products offer non-invasive sensing of 28mm (EFR-4) or 46mm (EFR-5) cables and are of fully encapsulated construction that protects against shock and vibration. Housed in flame retardant ABS material as standard the EFR-4/EFR-5 Built-in features include fail-safe operation, manual reset after fault trip, auto reset after power failure and trip status latched until reset (with power supply on). A Non-Failsafe version is available to special order – this should be used in applications where shunt tripping of primary/supply breakers makes failsafe impractical.

The EFR-4/EFR-5 relays react to alternating current only and will reject stray dc signals. They maintain accuracy over an extremely wide frequency band from 5Hz to 800Hz thus making them suitable for application on variable frequency drives. The relays can be used on solid, medium or high resistance grounded installations and, by using the recommended artificial ground package, even on ungrounded installations.