Why Choose the ABB CM-SRS.21P Current Monitoring Relay?
The ABB CM-SRS.21P, order code 1SVR740840R0400, is a compact and reliable current monitoring relay designed for monitoring AC and DC currents in industrial control, automation and electrical protection applications. As part of the ABB CM single-phase monitoring relay range, it provides configurable overcurrent or undercurrent monitoring to help detect abnormal operating conditions and protect equipment.
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 configured for a wide variety of current supervision tasks.
With a wide 24–240 V AC/DC rated control supply voltage, two changeover output contacts and maintenance-free push-in connection technology, the CM-SRS.21P provides flexible integration into industrial control panels. Its slim 22.5 mm housing helps conserve DIN-rail space while providing dependable current supervision.
Key Advantages
- Reliable overcurrent and undercurrent monitoring for AC and DC applications.
- Wide 24–240 V AC/DC control supply voltage simplifies integration across different control systems.
- Three selectable measuring ranges covering 3 mA to 1 A.
- Adjustable 3–30% hysteresis for application-specific switching behaviour.
- Adjustable 0 or 0.1–30 s tripping delay helps prevent unwanted switching caused by short-duration current changes.
- Two changeover contacts provide flexible signalling and control options.
- Maintenance-free push-in terminals support quick and convenient wiring.
- Compact 22.5 mm-wide housing saves control-panel space.
Key Features
- ABB CM-SRS current monitoring relay series.
- 24–240 V AC/DC 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.
- Push-in connection technology for efficient panel wiring.
- Operating ambient temperature range of -20 to +60 °C.
Reliable Current Monitoring for Industrial Control Systems
Current monitoring relays supervise electrical loads and circuits to identify operating currents 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 control systems.
Its three selectable measuring ranges enable monitoring from just 3 mA up to 1 A, while adjustable hysteresis and time delay provide flexibility when adapting the relay to specific equipment and processes. The wide AC/DC control supply range and push-in terminals further simplify installation in modern industrial control panels.
Typical Applications
- Industrial machinery current supervision.
- Overcurrent and undercurrent detection.
- Motor and electrical load monitoring.
- Detection of load loss or abnormal operating conditions.
- Industrial automation and process control systems.
- Electrical control and distribution panels.
