Why Choose the ABB CM-PAS.31S Three-Phase Monitoring Relay?
The ABB CM-PAS.31S (1SVR730774R1300) is a versatile three-phase monitoring relay designed to supervise phase failure, phase sequence and phase unbalance in industrial electrical systems. Part of the ABB CM-PAS monitoring relay series, it helps protect motors, machinery and electrical equipment against abnormal three-phase supply conditions.
Designed for a three-phase 160–300 V AC line-to-line measuring range, the CM-PAS.31S continuously monitors the connected electrical supply using a True RMS measuring principle. Its adjustable phase unbalance threshold and selectable tripping delay allow engineers to configure monitoring behaviour according to the requirements of the installation.
The relay features two change-over output contacts, an adjustable 0 or 0.1–30 s tripping delay and three LED status indicators. Powered directly by the monitored circuit, the ABB CM-PAS.31S requires no separate auxiliary supply. Its compact 22.5 mm DIN rail-mounted housing and screw-terminal connections make it suitable for industrial control cabinets and automated machinery.
Key Advantages
- Reliable three-phase supply monitoring for industrial electrical systems.
- Combined phase failure, phase sequence and phase unbalance detection.
- 160–300 V AC line-to-line measuring range for compatible three-phase networks.
- True RMS measurement supports dependable evaluation of monitored voltages.
- Adjustable phase unbalance threshold for application-specific supervision.
- Adjustable tripping delay from 0.1 to 30 s, with a separate zero-delay setting.
- Two change-over relay contacts provide flexible control and alarm signalling.
- 250 V AC / 4 A contact rating for appropriately rated control circuits.
- Self-powered operation eliminates the need for a separate auxiliary supply.
- Three integrated LEDs provide convenient operating and fault status indication.
- Front-mounted adjustments support straightforward commissioning.
- Double-chamber cage screw terminals provide reliable electrical connections.
- Compact 22.5 mm housing width saves control cabinet space.
- Optional sealable transparent cover helps protect settings against unauthorised adjustment.
- Helps reduce equipment downtime associated with missing phases, incorrect phase rotation and voltage imbalance.
Key Features
- ABB CM-PAS three-phase monitoring relay series.
- CM-PAS.31S model with screw-terminal connections.
- Phase failure monitoring for three-phase electrical supplies.
- Phase sequence monitoring for detection of incorrect phase rotation.
- Phase unbalance monitoring with an adjustable threshold.
- 160–300 V AC rated control supply and measuring voltage.
- 50/60 Hz supply frequency.
- Three-phase connections through L1, L2 and L3.
- True RMS measuring principle.
- Two change-over (SPDT) output contacts.
- 250 V AC / 4 A output contact rating.
- 200 ms start-up delay.
- 0 or 0.1–30 s adjustable tripping delay.
- ON-delayed tripping behaviour.
- Powered directly by the monitored three-phase supply.
- Three LED status indicators.
- Front-mounted controls for phase unbalance and time-delay settings.
- Double-chamber cage screw-terminal technology.
- DIN rail mounting for industrial control panels.
- IP50 housing protection and IP20 terminal protection.
- Optional ABB COV.11 sealable transparent cover.
Technical Specifications
- Manufacturer: ABB
- Series: CM-PAS Three-Phase Monitoring Relays
- Model: CM-PAS.31S
- ABB order code: 1SVR730774R1300
- ABB product group: 310921-Measuring & Monitoring Relays
- Product type: Three-phase monitoring relay
- Monitoring functions: Phase failure, phase sequence and phase unbalance
- Rated control supply voltage: 3 × 160–300 V AC
- Measuring voltage range: 160–300 V AC line-to-line
- Supply frequency: 50/60 Hz
- Supply type: Alternating current (AC)
- Monitored phases: L1, L2 and L3
- Neutral connection: Not required
- Measuring principle: True RMS (TRMS)
- Phase unbalance threshold: Adjustable
- Tripping delay: 0 s or adjustable from 0.1 to 30 s
- Start-up delay: 200 ms
- Tripping delay characteristic: ON-delay
- Auxiliary power supply: Not required; powered by measuring circuit
- Output contacts: 2 change-over contacts
- Contact configuration: 2 c/o (2 × SPDT)
- Contact rating: 250 V AC / 4 A
- Rated operational current AC-12: 4 A at 230 V AC
- Rated operational current AC-15: 3 A at 230 V AC
- Rated operational current DC-12: 4 A at 24 V DC
- Rated operational current DC-13: 2 A at 24 V DC
- Status indication: 3 LEDs
- Operating ambient temperature: -25 to +60 °C
- Storage temperature: -40 to +85 °C
- Housing protection rating: IP50
- Terminal protection rating: IP20
- Terminal type: Screw terminals
- Connection technology: Double-chamber cage screw terminals
- Mounting type: DIN rail mounting
- Dimensions (H × W × D): 85.6 × 22.5 × 103.7 mm
- Net weight: 0.133 kg
- EAN: 4016779851794
- Minimum order quantity: 1 piece
- Customs tariff number: 85364900
- RoHS compliance: Following EU Directive 2011/65/EU
Reliable Three-Phase Monitoring for Industrial Motor Protection
Industrial motors and automated machinery depend on stable three-phase electrical supplies for reliable operation. Missing phases, incorrect phase sequence and excessive voltage imbalance can cause motor overheating, reduced torque, unexpected shutdowns and equipment damage. The ABB CM-PAS.31S three-phase monitoring relay helps identify these conditions and provides switching signals that can be integrated into protective control circuits.
The CM-PAS.31S monitors the connected L1, L2 and L3 supply conductors and evaluates the voltage conditions using its True RMS measuring principle. If a monitored phase is lost, the phase sequence is incorrect or the measured phase unbalance exceeds the configured threshold, the relay responds according to its monitoring logic and selected delay setting.
The adjustable phase unbalance threshold allows the monitoring sensitivity to be matched to the requirements of the installation. This is particularly useful where supply voltage imbalance must be detected before it causes prolonged stress on motors or other three-phase equipment.
The relay also provides a configurable tripping delay of 0 or 0.1–30 s. This allows the response to be set for immediate monitoring or delayed operation, depending on the application. The delay is intended to help coordinate the relay response with the characteristics of the monitored electrical system.
With two change-over output contacts, the CM-PAS.31S can interface with compatible contactor control circuits, programmable logic controllers and alarm systems. The relay is a monitoring and signalling device rather than a circuit breaker or motor overload relay. Where disconnection of a motor supply is required, its contacts should operate an appropriately rated external switching device.
Its self-powered design, compact DIN rail housing and front-mounted adjustments simplify installation and commissioning. The three LED indicators provide convenient status information, while the optional ABB COV.11 transparent cover can help prevent unintended changes to the configured settings.
Typical Applications
- Three-phase industrial power supply monitoring.
- Phase failure detection in motor starter circuits.
- Incorrect phase sequence detection.
- Phase unbalance supervision for industrial motors.
- Industrial pump and pumping installations.
- Compressors and refrigeration equipment.
- Industrial fans, blowers and ventilation systems.
- Conveyor systems and material handling equipment.
- Automated production and packaging machinery.
- Industrial electrical distribution boards.
- Motor control centres and control cabinets.
- OEM machinery requiring three-phase supply supervision.
- Electrical automation systems with phase fault alarm signalling.
