1SVR740840R0400 ABB CM-SRS.21P Current Monitoring Relay 24-240 V AC/DC
ABB CM-SRS.21P 1SVR740840R0400 is a 24–240 V AC/DC current monitoring relay with three measuring ranges from 3 mA to 1 A, configurable overcurrent or undercurrent monitoring, two changeover contacts and push-in terminals.
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.
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.
Technical Specifications
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Time Delay
Adjustable
Monitored Supply
AC/DC
Signal / Input Range
3–30 mA
Monitoring Function
Current
Series
CM-SRS
ABB order code
1SVR740840R0400
Product group
310921 – Measuring & Monitoring Relays
Product type
Current monitoring relay
Monitoring function
Overcurrent or undercurrent monitoring
Rated control supply voltage
24–240 V AC/DC
Measuring principle
RMS
Measuring range 1
3–30 mA
Measuring range 2
10–100 mA
Measuring range 3
0.1–1 A
Hysteresis
Adjustable, 3–30% of threshold value
Tripping delay
0 s or adjustable 0.1–30 s
Output
2 c/o (SPDT) contacts
Connection technology
Push-in terminals
Operating temperature
-20 to +60 °C
Storage temperature
-40 to +85 °C
Width
22.5 mm
Height
85.6 mm
Depth
103.7 mm
Net weight
approx. 0.141 kg
Frequently Asked Questions
What is the ABB CM-SRS.21P used for?
The CM-SRS.21P is used for overcurrent or undercurrent monitoring of AC and DC currents in industrial electrical and automation systems.
What current range can the CM-SRS.21P monitor?
The relay provides three selectable measuring ranges: 3–30 mA, 10–100 mA and 0.1–1 A.
What supply voltage does the CM-SRS.21P require?
The ABB CM-SRS.21P operates with a wide 24–240 V AC/DC rated control supply voltage.
Does the CM-SRS.21P have an adjustable time delay?
Yes. The tripping delay can be set to 0 s or adjusted from 0.1–30 s, allowing short-duration current variations to be accommodated where required.
What type of terminals does the CM-SRS.21P use?
The CM-SRS.21P uses push-in terminals, providing maintenance-free connection technology for fast and convenient control-panel wiring.
Trusted ABB Monitoring Technology
ABB CM measuring and monitoring relays provide dependable supervision of electrical parameters in industrial automation, machinery and control-panel applications, helping operators identify abnormal conditions and maintain reliable system operation.
Time Delay
Adjustable
Monitored Supply
AC/DC
Signal / Input Range
3–30 mA
Monitoring Function
Current
Series
CM-SRS
ABB order code
1SVR740840R0400
Product group
310921 – Measuring & Monitoring Relays
Product type
Current monitoring relay
Monitoring function
Overcurrent or undercurrent monitoring
Rated control supply voltage
24–240 V AC/DC
Measuring principle
RMS
Measuring range 1
3–30 mA
Measuring range 2
10–100 mA
Measuring range 3
0.1–1 A
Hysteresis
Adjustable, 3–30% of threshold value
Tripping delay
0 s or adjustable 0.1–30 s
Output
2 c/o (SPDT) contacts
Connection technology
Push-in terminals
Operating temperature
-20 to +60 °C
Storage temperature
-40 to +85 °C
Width
22.5 mm
Height
85.6 mm
Depth
103.7 mm
Net weight
approx. 0.141 kg
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UK delivery
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This productManufacturer Lead Time
Estimated Delivery 9 weeks
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