Why Choose the ABB CM-SRS.21P Current Monitoring Relay?
The ABB CM-SRS.21P, order code 1SVR740841R0400, is a compact and reliable single-phase current monitoring relay designed for supervising AC and DC currents in industrial control, machinery and automation systems. As part of the ABB CM-SRS current monitoring relay series, it provides configurable overcurrent or undercurrent monitoring for detecting abnormal electrical load conditions.
The CM-SRS.21P uses an RMS measuring principle and provides three selectable current measuring ranges of 3–30 mA, 10–100 mA and 0.1–1 A. Adjustable hysteresis from 3–30% of the threshold value and an adjustable tripping delay of 0 or 0.1–30 s allow the relay to be adapted to different current supervision requirements.
With a rated control supply voltage of 110–130 V AC, two changeover output contacts and maintenance-free Easy Connect push-in terminal technology, the CM-SRS.21P is well suited to industrial control panels. Its compact 22.5 mm DIN-rail housing provides dependable monitoring while conserving valuable panel space.
Key Advantages
- Reliable overcurrent and undercurrent monitoring for industrial applications.
- 110–130 V AC rated control supply voltage.
- Three selectable measuring ranges covering 3 mA to 1 A.
- RMS measurement suitable for monitoring AC and DC currents.
- Adjustable 3–30% hysteresis enables application-specific switching behaviour.
- Adjustable 0 or 0.1–30 s tripping delay helps accommodate temporary current variations.
- Two changeover contacts provide flexible signalling and control options.
- Maintenance-free Easy Connect push-in terminals simplify panel wiring.
- Compact 22.5 mm-wide DIN-rail housing saves installation space.
Key Features
- ABB CM-SRS current monitoring relay series.
- 110–130 V AC rated control supply voltage.
- Configurable overcurrent or undercurrent monitoring.
- Current measuring ranges: 3–30 mA, 10–100 mA and 0.1–1 A.
- RMS measuring principle for AC and DC currents.
- Adjustable hysteresis of 3–30% of the threshold value.
- Adjustable tripping delay of 0 or 0.1–30 s.
- 2 c/o (SPDT) output contacts.
- Output contacts rated at 250 V / 4 A.
- Open-circuit operating principle.
- Easy Connect push-in connection technology.
- Operating ambient temperature range of -20 to +60 °C.
Reliable Current Monitoring for Industrial Control Systems
Current monitoring relays supervise electrical circuits and loads to identify current levels that move outside configured limits. The ABB CM-SRS.21P can be configured for either overcurrent or undercurrent monitoring, making it suitable for detecting overload conditions, loss of load and other abnormal current conditions in machinery and automation systems.
Its three selectable measuring ranges enable current monitoring from 3 mA up to 1 A, while adjustable hysteresis and tripping delay provide flexibility when adapting the relay to specific equipment. The 110–130 V AC control supply, two changeover contacts and push-in terminals support straightforward integration into industrial electrical panels.
Typical Applications
- Industrial machinery current supervision.
- Overcurrent and undercurrent detection.
- Motor and electrical load monitoring.
- Detection of load loss and abnormal current conditions.
- Pumps, fans, conveyors and processing machinery.
- Industrial automation and process control systems.
- Electrical control panels and switchboards.
