ABB 2CSM142120R1201 RD2 Type A residual current monitor with adjustable sensitivity and intervention delay, external toroidal transformer input and a 230-400 V AC operating supply.
£399.10
The ABB 2CSM142120R1201, also identified as the ABB RD2, is a reliable Type A residual current monitor designed to detect earth leakage currents in low-voltage electrical installations. Used together with a compatible external ABB toroidal transformer, it provides continuous residual current monitoring for cables, equipment and distribution systems.
The RD2 allows installers to adjust both the residual current sensitivity and intervention delay using integrated miniature DIP switches. This flexibility enables the monitor to be configured according to the protection and selectivity requirements of commercial, industrial and infrastructure applications.
Operating from a 230–400 V AC supply, the ABB RD2 is suitable for use in single-phase and three-phase electrical systems. Its compact 35 mm DIN rail housing occupies approximately two modular widths, helping panel builders add residual current monitoring without taking up excessive space inside the distribution board.
The ABB RD2 monitors the sum of the currents passing through an external toroidal transformer. Under normal operating conditions, the currents remain balanced. When insulation deterioration, equipment damage or another earth fault creates a leakage current, the monitor detects the resulting imbalance and activates its output relay.
The relay output can be connected to an alarm, signalling system, contactor or circuit breaker release. This allows the installation to warn operators or disconnect affected equipment when the configured residual current threshold and delay are exceeded.
| Manufacturer | ABB |
|---|---|
| Series | RD |
| Model | RD2 |
| Product ID | 2CSM142120R1201 |
| EAN | 8012542058007 |
| Product type | Residual current monitor |
| Device classification | Residual current monitoring relay |
| Residual current type | Type A |
| Operating voltage | 230–400 V AC |
| Rated frequency | 50 / 60 Hz |
| Residual current sensitivity | Adjustable |
| Intervention time | Adjustable |
| Maximum adjustable delay | 5 seconds |
| Minimum adjustable delay | 0.3 seconds |
| Output contact | 1 changeover contact |
| External transformer | Required |
| Pre-alarm output | No |
| Mounting type | DIN rail |
| Width | 35 mm |
| Height | 85 mm |
| Depth | 65 mm |
| Net weight | Approx. 0.105 kg |
| Power loss | Approx. 3.4 W |
| Connection type | Screw terminals |
| Standard | IEC/EN 62020 |
| HS Code | 85364190 |
| Country of Manufacture | Romania |
It continuously monitors electrical circuits for residual or earth leakage currents and activates an output relay when the configured threshold is exceeded.
No. The RD2 is a monitoring relay rather than a circuit breaker. Its changeover output can control an alarm, contactor or compatible circuit breaker release.
Yes. The monitor must be connected to a compatible external ABB toroidal transformer through which the monitored conductors are routed.
Yes. Both the residual current sensitivity and the intervention delay can be configured using the miniature DIP switches on the device.
Yes. The RD2 is suitable for both single-phase and three-phase electrical systems and operates from a 230–400 V AC supply.
ABB RD residual current monitors provide flexible earth leakage detection for panel builders, electrical engineers and maintenance teams responsible for protecting critical low-voltage installations.
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2025 has been a big year for LED Controls, and our blog has expanded accordingly. We've covered a wide range of topics across industrial control and factory automation this year. From core technology explainers and new product releases to panel building best practice...