Why Choose the ABB RD3-48 Residual Current Relay?
The ABB RD3-48 is a modular Type A electronic residual current relay designed for residual current protection and earth leakage monitoring in industrial low-voltage electrical installations. As part of the ABB RD3 residual current relay series, it operates with an external ABB TR family toroidal transformer to detect residual current and provide a switching output for the associated protective device.
The RD3-48 provides extensive adjustment for protection coordination, with residual current sensitivity settings from 0.03–30 A and selectable tripping delays from 0–10 s. These settings allow the relay to be configured for different leakage thresholds and selective protection requirements while its Type A detection is suitable for alternating and pulsating DC residual currents.
Designed for DIN-rail mounting, the RD3-48 occupies 3 modules and operates from a 12–48 V AC/DC supply. ABB specifies the RD3 family for use with external TR toroidal transformers and protective devices including S200 miniature circuit breakers and Tmax/XT moulded case circuit breakers, providing a flexible residual current protection solution for industrial distribution systems.
Key Advantages
- Electronic residual current protection and monitoring for industrial installations.
- 12–48 V AC/DC operating voltage suitable for low-voltage control systems.
- Wide 0.03–30 A sensitivity adjustment for flexible earth leakage protection.
- Selectable 0–10 s tripping delay supports protection coordination.
- Type A residual current detection for AC and pulsating DC residual currents.
- Works with external ABB TR family toroidal transformers.
- Compact 3-module DIN-rail design for straightforward switchboard installation.
- Provides two output contacts for status and protection signalling.
Key Features
- ABB RD3 electronic residual current relay series.
- 12–48 V AC/DC operating voltage.
- 0.03 / 0.1 / 0.3 / 0.5 / 1 / 2 / 3 / 5 / 10 / 30 A sensitivity settings.
- 0 / 0.06 / 0.2 / 0.3 / 0.5 / 1 / 2 / 3 / 5 / 10 s tripping time settings.
- 8 A at 250 V AC output contact capacity.
- Maximum 3 Ω resistance between toroidal transformer and relay.
- Remote reset connection length up to 15 m.
- IP20 protection rating.
- Maximum terminal conductor section of 2.5 mm².
- Complies with IEC/EN 60947-2 Annex M and IEC/EN 62020.
Reliable Residual Current Protection for Industrial Installations
The ABB RD3-48 works with an external toroidal transformer surrounding the active conductors of the monitored circuit. Under normal conditions the vector sum of the conductor currents is effectively zero; when insulation leakage or an earth fault produces an imbalance, the toroid detects the resulting residual current and sends the measurement signal to the relay.
The RD3-48 compares this signal with the selected sensitivity and time-delay settings. When the configured operating conditions are reached, its output contacts can initiate the required protection or signalling action. The broad adjustment ranges make the relay suitable for coordinated earth leakage protection in industrial switchboards and distribution systems.
Typical Applications
- Industrial residual current and earth leakage protection.
- Low-voltage switchboards and distribution panels.
- Industrial machinery and production equipment.
- Electrical systems using ABB S200 miniature circuit breakers.
- Installations using compatible ABB Tmax/XT moulded case circuit breakers.
- Control panels requiring adjustable earth fault monitoring.
