ELR series

Monitoring and protection of the low voltage distribution network

Front panel residual current relays are electronic devices used in combination with an external toroidal transformer. The choice of toroidal transformers is made according to the useful diameter and the minimum value of the leakage current to be detected.

The range of ELR front panel residual current relays has been tested in combination with miniature circuit breakers (S200 range) and moulded case circuit breakers (Tmax series up to T5 630 A) conforming with IEC/EN 60947-2 Annex M.

Main benefits

Guaranteed compliance

Compliant with IEC/EN 60947-2 Annex M. The range is tested within a configuration that includes residual current relays, toroids, shunt-trips, MCCBs and MCBs available in ABB offer

Continuous operation

Allows continuity of operations by signaling first in case of leakage current detection for quick interventions

Wide range

Wide range of products, toroids, and features to cover several applications and markets

Product details

Carrying out the protection

Flexibility and ease of use

Unique set of features

Thanks to the residual current relays it is possible to measure the leakage current to earth. These relays work in conjunction with a separate external toroid.

The value of the fault current is constantly detected by the toroid: when the residual current relay receives a signal from the toroid, it switches its output contacts. Then the shunt-trip opens the circuit breaker.

Also the Fail Safe function prevents the line from not being protected when there is no auxiliary power to the device.

Adjusting sensitivity from 0.03 to 30 A and the tripping times from 0 to 5 seconds, thus ensuring flexibility for many applications.

Remote Reset and Autoreset functions. The output contacts of the ELR residual current relays can be reset remotely, using push-buttons. Also, when the fault will be removed from the network, the relay contacts will switch automatically, without the need to press the reset button from a local or remote position.

• Fail Safe: The ELR range allows, through a selector switch, to enable or not the fail-safe function. If Fail safe is OFF, the relay activates the shunt-trip once the fault current is detected and also when there is no connection between the relay and toroid. If Fail Safe is ON, the relay activates the shunt-trip also when there is lack of supply to the residual current relay.

• Alarm (72P and 96P versions only): If the alarm function is ON, the alarm contact switches when the fault current exceeds 60% of the threshold lΔn selected.

• Frequency filtering (ELR96PF and ELR96PD versions only): This feature makes the relay stronger in presence of currents with harmonic components that are not due to an effective fault in the circuit but they are typically caused by the presence of electronic filters (e.g. when using frequency converters driving motors)

• Fault Memory LED (ELR96PF version only): The fault memory LED turns on in case of a fault and is only resettable manually. In this way it is possible to know if the relay has tripped even if the fault is no longer present and the contacts have returned into the standard position thanks to the autoreset

• Digital display (ELR96PD version only): The digital display allows instant reading of the value of earth leakage current. It is possible, through a minidip, to block the display on the residual current value that has generated the intervention of the circuit breaker

Product range

ELR48P

Type A relay with fail-safe and auto-reset functions.
(48x48 mm)

ELR72

Type A relay with fail-safe and auto-reset functions.
(72x72 mm).
P-Version available with pre-alarm threshold function

ELR96

Type A relay with fail-safe and auto-reset functions.
(96x96 mm).
• P-Version available with pre-alarm threshold function
• PF-Version available with frequency filter function
• PD-Version available with Led display bar indicator

Toroidal Transformers

Toroids allow the detection of earth fault current and are designed to be combined with the ELR series.

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