Why Choose the ABB CM-MSS.23P Thermistor Motor Protection Relay?
The ABB CM-MSS.23P (1SVR740700R2200) is a reliable thermistor motor protection relay designed to monitor electric motor winding temperatures and help protect industrial motors against overheating. Part of ABB's CM-MSS measuring and monitoring relay range, it evaluates signals from built-in PTC thermistor sensors to detect excessive motor temperatures caused by overload, insufficient cooling or demanding operating conditions.
The CM-MSS.23P operates from a selectable 110–130 V AC or 220–240 V AC control supply and features one PTC thermistor sensor circuit. It provides two changeover (SPDT) output contacts rated at 250 V / 4 A, allowing motor temperature faults to be communicated to contactors, PLC inputs and industrial alarm systems.
With configurable automatic, manual or remote reset, closed-circuit operation and ABB's maintenance-free Easy Connect push-in terminals, the CM-MSS.23P offers flexible integration into industrial motor control applications. Its compact 22.5 mm DIN rail housing makes it suitable for motor control centres, machinery panels and automation cabinets where reliable thermal protection and efficient installation are important.
Key Advantages
- Reliable motor winding temperature protection using PTC thermistor sensors.
- Helps detect overheating caused by motor overload, insufficient cooling and abnormal operating conditions.
- Dual AC control supply ranges: 110–130 V AC or 220–240 V AC.
- One PTC sensor measuring circuit for direct motor temperature supervision.
- Two changeover (SPDT) output contacts rated at 250 V / 4 A.
- Configurable automatic, manual or remote reset following a temperature fault.
- Closed-circuit operating principle for dependable fault signalling.
- ABB Easy Connect Technology with maintenance-free push-in terminals.
- Front-mounted reset button for convenient local operation.
- Overvoltage-protected supply and measuring inputs.
- Designed according to IEC 60947-8 for thermistor motor protection applications.
- Compact 22.5 mm housing width helps conserve control cabinet space.
- Tool-free DIN rail mounting and removal.
- Flame-retardant housing classified UL 94 V-0.
- Optional sealable transparent cover helps prevent unauthorised adjustments.
Key Features
- ABB CM-MSS.23P thermistor motor protection relay.
- Manufacturer order code: 1SVR740700R2200.
- Rated control supply voltage: 110–130 V AC or 220–240 V AC.
- Monitoring function: Motor winding temperature supervision.
- Sensor technology: PTC thermistor temperature sensors.
- Number of measuring circuits: 1.
- Reset functions: Automatic, manual or remote reset.
- Local reset: Front-mounted reset button.
- Operating principle: Closed-circuit principle.
- Output configuration: 2 changeover (SPDT) contacts.
- Output contact rating: 250 V / 4 A.
- Terminal technology: Easy Connect push-in terminals.
- Screwless, maintenance-free spring-clamp connections.
- Overvoltage-protected supply and measuring inputs.
- Motor protection functionality according to IEC 60947-8.
- Operating and relay status indication.
- Housing width: 22.5 mm.
- DIN rail mounting for industrial electrical panels.
- Optional sealable transparent protective cover.
Technical Specifications
- Manufacturer: ABB
- Product series: CM-MSS
- Model: CM-MSS.23P
- ABB order code: 1SVR740700R2200
- ABB product group: 310921-Measuring & Monitoring Relays
- Product type: Thermistor motor protection relay
- Rated control supply voltage: 110–130 V AC / 220–240 V AC
- Supply type: AC
- Monitoring function: Motor winding temperature monitoring
- Sensor type: PTC thermistors
- Number of sensor circuits: 1
- Reset modes: Automatic, manual or remote
- Local reset facility: Front-mounted reset button
- Operating principle: Closed-circuit principle
- Output contacts: 2 changeover (SPDT) contacts
- Contact rating: 250 V / 4 A
- Terminal type: Easy Connect push-in terminals
- Connection technology: Screwless spring-clamp connection
- Input protection: Overvoltage-protected supply and measuring inputs
- Applicable product standard: IEC 60947-8
- Additional product standard: IEC/EN 60947-5-1
- Housing protection rating: IP50
- Terminal protection rating: IP20
- Mounting type: DIN rail mounting
- Housing flammability classification: UL 94 V-0
- Operating ambient temperature: −25 to +60 °C
- Storage temperature: −40 to +85 °C
- Dimensions (H × W × D): 85.6 × 22.5 × 103.7 mm
- Net weight: 0.163 kg
- EAN: 4013614496585
- Customs tariff number: 85364900
Reliable Thermistor-Based Motor Temperature Protection
The ABB CM-MSS.23P monitors the resistance of PTC thermistor sensors embedded within electric motor windings. When the motor temperature approaches the thermistor's specified response temperature, sensor resistance increases sharply. The relay detects this change and switches its output contacts to indicate an overheating condition.
Unlike motor protection methods based exclusively on current measurement, PTC thermistor monitoring responds to the actual thermal condition of the motor windings. This makes it particularly useful for identifying overheating associated with heavy-duty starting, frequent switching, elevated ambient temperatures, insufficient cooling or mechanical operating problems.
The CM-MSS.23P provides one PTC sensor measuring circuit and operates according to the closed-circuit principle. During normal operation, the output relay remains energised. When a monitored temperature fault occurs, the output changes state, enabling a correctly designed control circuit to disconnect the motor, activate an alarm or notify a PLC.
Its two changeover output contacts allow the thermal protection signal to be incorporated into industrial control and monitoring arrangements. One contact may be used for a motor contactor control circuit while the other provides a separate indication, provided the installation follows the manufacturer's contact ratings and wiring requirements.
Flexible Reset Functions for Industrial Motor Control
The ABB CM-MSS.23P supports automatic, manual and remote reset after the monitored motor temperature has returned to an acceptable condition.
With automatic reset, the relay can return to its normal state once the overheating condition clears. Manual reset requires operator intervention using the front-mounted reset button, while remote reset allows the relay to be reset through a suitable external control arrangement.
The appropriate reset function should be selected according to the machine's operating requirements and safety assessment. Where unexpected motor restarting could create a hazard, the complete control system must incorporate suitable restart prevention, interlocking and protective measures. The reset function of the thermistor relay alone does not replace a machinery safety control system.
ABB Easy Connect Push-In Terminal Technology
The CM-MSS.23P features ABB's Easy Connect Technology, using push-in terminals instead of conventional screw connections. This allows suitable conductors to be connected securely through a spring-clamp mechanism, simplifying electrical panel wiring and reducing the need for routine terminal retightening.
Combined with its 22.5 mm DIN rail housing, the push-in terminal design makes the CM-MSS.23P particularly suitable for OEM equipment, production machinery and industrial automation panels where consistent wiring quality and efficient installation are important.
The relay is designed according to IEC 60947-8 and incorporates overvoltage-protected supply and measuring inputs. Correct sensor selection, wiring and protective device coordination remain essential for reliable operation.
Typical Applications
- Motor winding temperature protection in industrial machinery.
- Thermal monitoring of motors equipped with built-in PTC thermistors.
- Industrial motor control centres and electrical control cabinets.
- Pump motor overheating protection.
- Fan and ventilation motor temperature supervision.
- Compressor motor thermal protection.
- Conveyor and material handling equipment.
- Manufacturing and processing machinery.
- Industrial motors subject to frequent starting and stopping.
- Motor protection in high ambient temperature environments.
- PLC-based motor fault monitoring and alarm signalling.
- Industrial control systems using 110–130 V AC or 220–240 V AC supplies.
- OEM machinery requiring compact DIN rail motor protection.
- Applications requiring local or remote fault reset.
