Why Choose the ABB CM-SRS.21P Current Monitoring Relay?
The ABB CM-SRS.21P, order code 1SVR740841R1400, is a compact and reliable single-phase current monitoring relay designed for supervising electrical current in industrial machinery, control and automation systems. As part of the ABB CM-SRS current monitoring relay series, it provides selectable overcurrent or undercurrent monitoring for detecting abnormal electrical load conditions.
The CM-SRS.21P provides three selectable measuring ranges of 3–30 mA, 10–100 mA and 0.1–1 A. This broad low-current measuring capability makes the relay suitable for applications such as load supervision, loss-of-load detection and monitoring electrical equipment for excessive or insufficient operating current.
With a rated control supply voltage of 220–240 V AC, two changeover (SPDT) output contacts and push-in terminal technology, the CM-SRS.21P provides flexible integration into industrial control panels. An adjustable tripping delay of 0 or 0.1–30 s helps distinguish sustained abnormal current conditions from brief fluctuations.
Key Advantages
- Reliable overcurrent and undercurrent monitoring for industrial applications.
- 220–240 V AC rated control supply voltage.
- Three selectable current measuring ranges covering 3 mA to 1 A.
- Suitable for monitoring both AC and DC currents.
- Adjustable 0 or 0.1–30 s tripping delay accommodates temporary current variations.
- Two changeover (SPDT) contacts provide flexible signalling and control outputs.
- Push-in terminals support efficient, maintenance-friendly control-panel wiring.
- Compact 22.5 mm-wide housing conserves DIN-rail space.
Key Features
- ABB CM-SRS current monitoring relay series.
- 220–240 V AC rated control supply voltage.
- Selectable overcurrent or undercurrent monitoring.
- Current measuring ranges of 3–30 mA, 10–100 mA and 0.1–1 A.
- RMS current measurement.
- Adjustable tripping delay of 0 or 0.1–30 s.
- 2 c/o (SPDT) output contacts.
- Push-in connection technology.
- Compact DIN-rail mounting format.
- Operating ambient temperature range of -20 to +60 °C.
Reliable Current Monitoring for Industrial Control Systems
Current monitoring relays supervise electrical circuits and loads by comparing measured current with a configured operating threshold. The ABB CM-SRS.21P can be used for either overcurrent or undercurrent monitoring, allowing a control system to respond when current rises above or falls below the required operating level.
The three selectable measuring ranges enable supervision from 3 mA up to 1 A, while the adjustable tripping delay can help prevent short-duration current fluctuations from causing unnecessary switching. Its 220–240 V AC control supply, dual changeover outputs and push-in terminals make it well suited to industrial electrical panels and automation cabinets.
Typical Applications
- Industrial machinery current supervision.
- Overcurrent and undercurrent detection.
- Motor and electrical load monitoring.
- Loss-of-load detection.
- Pumps, fans, conveyors and processing machinery.
- Industrial automation and process control systems.
- Electrical control panels and switchboards.
