Why Choose the ABB RD3M Residual Current Relay?
The ABB RD3M is a DIN-rail mounted electronic Type A residual current relay designed to provide residual current protection and earth leakage monitoring in industrial low-voltage installations. As part of ABB’s Earth Monitoring Devices range, it operates with an external ABB TR-series toroidal transformer and can be combined with suitable circuit-breaking equipment to create a coordinated residual current protection system.
The RD3M adds pre-alarm threshold and frequency filter functions to the RD3 residual current relay platform. The pre-alarm function enables developing leakage conditions to be signalled before the main protection threshold is reached, while frequency filtering helps improve continuity of service by reducing unwanted operation caused by leakage-current components outside the relevant measurement range.
Designed for a 230–400 V AC operating voltage and 50–60 Hz systems, the RD3M is suitable for industrial distribution boards, switchboards and control panels. Its compact three-module DIN-rail format and compatibility with ABB S200 miniature circuit breakers and Tmax moulded-case circuit breakers make it a flexible solution for residual current protection and monitoring.
Key Advantages
- Electronic Type A residual current protection and monitoring for industrial installations.
- 230–400 V AC operating voltage for common low-voltage distribution systems.
- Pre-alarm functionality provides early indication of developing earth leakage conditions.
- Frequency filter function helps reduce unwanted operation and improve service continuity.
- Adjustable operating delay up to 10 s supports protection coordination and selectivity.
- Compact three-module DIN-rail mounting simplifies integration into electrical panels.
Key Features
- ABB RD3 electronic residual current relay series.
- Type A residual current characteristic.
- 230–400 V AC rated operational voltage.
- 400 V AC rated control supply voltage.
- 50–60 Hz rated frequency.
- Pre-alarm threshold function for advance leakage-current indication.
- Frequency filter for residual current monitoring.
- 0–10 s adjustable operating delay.
- Provides RMS measurement of earth leakage current.
- Designed for use with external ABB TR-series toroidal transformers.
- Compatible with ABB S200 MCBs and Tmax moulded-case circuit breakers up to T5.
- DIN-rail mounting with a three-module width.
- Complies with IEC/EN 60947-2 Annex M.
Flexible Residual Current Protection for Industrial Systems
The ABB RD3M operates with an external toroidal transformer through which the active conductors of the protected circuit are routed. Under normal operating conditions, the currents passing through the toroid balance each other. An insulation fault or leakage to earth creates a residual current imbalance, which is detected by the transformer and evaluated by the RD3M.
The RD3M performs RMS measurement of earth leakage current and combines configurable protection with pre-alarm and frequency filtering functions. When used with appropriate tripping equipment, the relay can be combined with ABB S200 miniature circuit breakers and Tmax moulded-case circuit breakers up to T5, enabling coordinated residual current protection while supporting selectivity and continuity of service in industrial installations.
Typical Applications
- Industrial low-voltage distribution systems.
- Electrical switchboards and distribution panels.
- Industrial machinery and automation systems.
- Installations requiring residual current pre-alarm monitoring.
- Earth leakage monitoring with ABB TR-series toroidal transformers.
- Protection systems incorporating ABB S200 MCBs or compatible Tmax moulded-case circuit breakers.
