Differential Relay 2 MODULES

The Legrand 026088 residual current relay is an adjustable modular device designed to detect earth leakage currents and trigger the disconnection of a compatible circuit breaker or power breaker. Used together with a toroidal transformer and a current release coil or undervoltage release coil, it makes it possible to add residual current protection to installations equipped with Legrand DPX³ or DPX³-I circuit breakers.

It features adjustable residual current sensitivity, adjustable trip delay, status indication via multiple LEDs, and an auxiliary contact. It is powered at 230/240 volts AC, operates at 50 or 60 hertz, and takes up only 2 modules on DIN rail.

Adjustable residual current relay for Legrand DPX³ circuit breakers

Reference 026088 is designed to continuously monitor possible earth fault currents in electrical installations. The relay receives the signal from an external toroidal transformer installed around the circuit conductors and compares the detected residual current with the selected sensitivity value.

When the leakage current reaches the configured threshold and the set timing conditions are met, the relay sends a trip command to the coil associated with the breaker, causing the circuit to open.

Residual current protection using relay and toroidal transformer

The Legrand 026088 is not a standalone residual current circuit breaker. To perform the protection function, it must work together with a compatible toroid and a current release coil or undervoltage release coil installed in the corresponding circuit breaker or power breaker.

This architecture makes it possible to add residual current protection to power breakers and adapt the operating parameters to the specific needs of the installation.

Adjustable residual current sensitivity

One of the relay’s main advantages is the ability to adjust the trip residual current. The available range depends on the associated toroidal transformer.

With the smallest compatible toroids, Legrand provides sensitivity values from 0.03 amperes to 30 amperes, with different intermediate adjustment steps.

Available values include 0.03; 0.05; 0.075; 0.1; 0.15; 0.2; 0.3; 0.5; 0.75; 1; 1.5; 2; 3; 5; 7.5; 10; 15; 20 and 30 amperes, depending on the toroid used.

Adjustable trip delay up to 5 seconds

The Legrand 026088 also allows the operating delay to be configured. The selectable times are:

• 0 seconds.
• 0.15 seconds.
• 0.25 seconds.
• 0.5 seconds.
• 1 second.
• 2.5 seconds.
• 5 seconds.

This adjustment makes it possible to adapt the protection response and helps coordinate different levels of an electrical installation when the design requires different operating times.

Type A residual current relay

Legrand identifies this reference as a Type A residual current relay. This type of protection is designed to detect sinusoidal alternating residual currents and pulsating direct currents within the conditions defined for this class.

The sensitivity value, timing, and toroid must be selected according to the characteristics of the circuit and the protection requirements established for the installation.

LED indicators for leakage current monitoring

The front panel of the relay includes several LED indicators that make it easy to visually monitor the protection status.

• 1 green LED: indicates that the relay is powered.
• 3 yellow LEDs: indicate insulation fault current levels equivalent to 20, 40, and 60 percent of the configured threshold.
• 1 steady red LED: indicates that the set fault current value has been reached or exceeded.
• 1 flashing red LED: indicates an interruption or loss of continuity in the connection between the toroidal transformer and the relay.

This signaling makes it possible to quickly check the evolution of leakage current and helps identify certain connection faults.

Progressive insulation level monitoring

The three yellow indicators allow the fault current level to be displayed in stages relative to the selected threshold. The 20, 40 and 60 percent levels provide advance information before the current configured for relay operation is reached.

This indication can be especially useful during maintenance and installation diagnostics, as it allows residual current increases to be observed before tripping occurs.

Built-in auxiliary contact

The Legrand 026088 includes an auxiliary contact that can be used within the installation’s control or signaling system.

Integrating this contact makes it easier to monitor the relay status in electrical panels and compatible management systems.

Sealable front cover

The device features a hinged, sealable front cover. This cover protects the adjustment elements and helps prevent accidental or unauthorized changes to the configured parameters.

This feature is especially useful in professional installations where it is important to preserve the sensitivity and timing settings established during commissioning.

Compatible with Legrand toroidal transformers

The relay must be used together with the compatible Legrand toroidal transformers specified for reference 026088. The manufacturer’s current documentation includes different diameters to suit various cable cross-sections and installation sizes.

The diameter of the selected toroid affects the minimum available residual current sensitivity range, so it must be chosen together with the relay according to the electrical and physical characteristics of the circuit.

Modular DIN rail mounting

The relay is designed to be installed directly on DIN rail in electrical panels. It occupies a width equivalent to 2 modules, making it easy to integrate alongside other control and protection devices.

Its modular format makes it possible to concentrate the detection and adjustment functions in the panel, while the toroidal transformer is installed around the conductors to be monitored.

230/240 volt power supply

The Legrand 026088 operates with a power supply voltage of 230/240 volts AC and a frequency of 50 or 60 hertz.

The front green LED allows you to visually confirm that the relay is correctly powered and ready to perform residual current monitoring.

Application with DPX³ and DPX³-I circuit breakers

Legrand specifies this reference to provide residual current protection when combined with DPX³ circuit breakers fitted with a trip coil or with compatible DPX³-I circuit breakers.

When the relay detects a fault current above the selected level, it transmits the corresponding command to the associated coil to cause the switching device to open.

Legrand 026088 technical characteristics

• Brand: Legrand.
• Reference: 026088.
• EAN: 3245060260880.
• Product type: adjustable modular residual current relay.
• Residual current protection type: Type A.
• Application: residual current protection associated with compatible DPX³ and DPX³-I circuit breakers.
• Operation: detection via external toroidal transformer.
• Residual current sensitivity: adjustable according to associated toroid.
• Minimum available sensitivity: 0.03 amperes with compatible toroids.
• Maximum available sensitivity: 30 amperes.
• Adjustable delay: 0; 0.15; 0.25; 0.5; 1; 2.5 and 5 seconds.
• Power supply voltage: 230/240 volts AC.
• Frequency: 50 or 60 hertz.
• Power indicator: green LED.
• Leakage level indicators: 3 yellow LEDs at 20, 40 and 60 percent.
• Fault indicator: red LED.
• Detection of interruption between toroid and relay: yes, via flashing red LED.
• Auxiliary contact: included.
• Front cover: hinged and sealable.
• Mounting: DIN rail.
• Number of modules: 2.
• Requires toroidal transformer: yes.
• Requires compatible trip coil: yes.

Adjustable residual current protection for power panels

The Legrand 026088 residual current relay makes it possible to add adjustable residual current protection to installations with compatible power breakers, offering regulation of both the sensitivity and operating time.

Its 2-module format, LED indicators, auxiliary contact, sealable cover, and compatibility with different toroidal transformers make it easy to integrate into electrical panels where leakage currents must be monitored and tripping adapted to the specific characteristics of the installation.