Why Choose the ABB CM-PSS.31P Three-Phase Monitoring Relay?
The ABB CM-PSS.31P (1SVR740784R2300) is a compact industrial three-phase monitoring relay designed to supervise electrical supply conditions in motor control systems, production machinery and industrial distribution panels. Part of ABB's CM-PSS measuring and monitoring relay range, it detects phase failure, incorrect phase sequence, overvoltage and undervoltage, helping control systems respond to potentially damaging supply faults.
Designed for a nominal 3 × 380 V AC three-phase supply, the CM-PSS.31P operates directly from the monitored circuit without a separate auxiliary power supply. Its measuring range is 342–418 V AC line-to-line, corresponding to fixed overvoltage and undervoltage response thresholds of approximately ±10% of the 380 V nominal voltage. Unlike adjustable-threshold CM-MPS models, the CM-PSS.31P uses fixed voltage thresholds for straightforward supply supervision.
The relay incorporates a true RMS (TRMS) measuring principle, selectable phase sequence monitoring and a configurable instantaneous or 0.1–30 s tripping delay. With two changeover (SPDT) output contacts rated at 250 V / 4 A, three LED status indicators and maintenance-free ABB Easy Connect push-in terminals, it provides a practical monitoring solution in a compact 22.5 mm DIN rail housing.
Key Advantages
- Four essential three-phase monitoring functions in one compact relay.
- Phase failure detection helps identify the loss of a supply phase.
- Selectable phase sequence monitoring helps detect incorrect phase rotation.
- Overvoltage and undervoltage monitoring with fixed response thresholds.
- Designed for 3 × 380 V AC three-phase electrical networks.
- 342–418 V AC measuring range for nominal 380 V systems.
- True RMS measuring principle supports dependable voltage evaluation.
- Powered directly by the monitored supply, eliminating a separate auxiliary supply.
- Two changeover (SPDT) contacts rated at 250 V / 4 A.
- Adjustable tripping delay: 0 s or 0.1–30 s.
- Selectable ON-delayed or OFF-delayed tripping response.
- Three LEDs provide convenient operating and fault indication.
- Easy Connect push-in terminals simplify installation and reduce wiring maintenance.
- 22.5 mm DIN rail housing saves valuable control cabinet space.
- Front-mounted operating controls simplify commissioning.
- Optional sealable transparent cover helps protect configured settings.
Key Features
- ABB CM-PSS.31P three-phase monitoring relay.
- ABB order code: 1SVR740784R2300.
- Rated control supply voltage: 3 × 380 V AC.
- Measuring voltage: 342–418 V AC, line-to-line.
- Rated frequency: 50/60 Hz.
- Phase failure monitoring: Integrated.
- Phase sequence monitoring: Selectable.
- Overvoltage monitoring: Fixed upper threshold.
- Undervoltage monitoring: Fixed lower threshold.
- Voltage threshold setting: ±10% of nominal voltage.
- Measuring principle: True RMS (TRMS).
- Start-up delay: 200 ms.
- Tripping delay: 0 s or 0.1–30 s.
- Delay mode: Selectable ON-delayed or OFF-delayed.
- Output configuration: 2 changeover (SPDT) contacts.
- Contact rating: 250 V / 4 A.
- Supply arrangement: Powered by the monitored three-phase circuit.
- Status indication: 3 LEDs.
- Connection technology: Easy Connect push-in terminals.
- Housing width: 22.5 mm.
- Tool-free DIN rail mounting and removal.
- Optional sealable transparent protective cover.
Technical Specifications
- Manufacturer: ABB
- Product series: CM-PSS
- Model: CM-PSS.31P
- ABB order code: 1SVR740784R2300
- ABB product group: 310921-Measuring & Monitoring Relays
- Product type: Three-phase monitoring relay
- Rated control supply voltage: 3 × 380 V AC
- Rated measuring voltage: 3 × 380 V AC
- Measuring range (L-L): 342–418 V AC
- Rated supply frequency: 50/60 Hz
- Supply terminals: L1, L2, L3
- Auxiliary supply: Not required; powered by the monitored circuit
- Measuring principle: True RMS (TRMS)
- Phase failure monitoring: Yes
- Phase sequence monitoring: Selectable
- Overvoltage monitoring: Yes
- Undervoltage monitoring: Yes
- Voltage response thresholds: Fixed at ±10% of nominal voltage
- Nominal undervoltage threshold: 342 V AC
- Nominal overvoltage threshold: 418 V AC
- Start-up delay: 200 ms
- Tripping delay: 0 s or 0.1–30 s
- Tripping delay selection: ON-delayed or OFF-delayed
- Output contacts: 2 changeover (SPDT)
- Contact rating: 250 V / 4 A
- UL/CSA contact rating: B300
- Maximum UL/CSA output operating voltage: 300 V AC
- Rated insulation voltage: 600 V input/output circuits; 300 V between output circuits
- Status indication: 3 LEDs
- Terminal type: Easy Connect push-in terminals
- Connection technology: Screwless spring-clamp connection
- Housing protection rating: IP50
- Terminal protection rating: IP20
- Housing flammability classification: UL 94 V-0
- Mounting type: DIN rail mounting
- 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: 0.123 kg
- EAN: 4016779851992
- Customs tariff number: 85364900
Reliable Three-Phase Voltage and Supply Monitoring
The ABB CM-PSS.31P continuously monitors the line-to-line voltages of a nominal 380 V AC three-phase electrical network. Its primary purpose is to identify abnormal supply conditions and provide a switching signal that can be used by an industrial control system.
Phase failure monitoring helps detect the loss of one of the three supply phases. A missing phase can cause serious operating problems in three-phase motors, including reduced torque, increased heating and abnormal equipment performance.
Phase sequence monitoring identifies incorrect phase rotation. This is particularly important for equipment such as pumps, fans, compressors and conveyors, where reversing the phase sequence may cause the motor to rotate in the wrong direction.
The phase sequence function can be switched off where phase rotation supervision is not required, allowing the relay to be adapted to the needs of the installation.
The CM-PSS.31P also monitors overvoltage and undervoltage. Its fixed thresholds provide a straightforward means of supervising supply voltage conditions without requiring individual adjustment of the upper and lower voltage limits.
Fixed ±10% Voltage Thresholds for 380 V AC Systems
The CM-PSS.31P is designed for a nominal 380 V AC line-to-line supply, with fixed voltage thresholds corresponding to approximately ±10% of the rated voltage.
The nominal lower threshold is 342 V AC, while the nominal upper threshold is 418 V AC. These values define the relay's specified voltage monitoring range.
This fixed-threshold arrangement is useful in installations where the required voltage tolerance is already established and additional threshold adjustment is unnecessary. It also helps simplify commissioning by reducing the number of settings that must be configured.
The relay uses a true RMS measuring principle, providing voltage evaluation based on the effective value of the monitored AC waveform.
For applications requiring adjustable voltage limits, phase unbalance monitoring or a different nominal supply voltage, an alternative ABB monitoring relay should be selected.
Adjustable Tripping Delay and Flexible Fault Signalling
The ABB CM-PSS.31P provides an adjustable tripping delay that can be switched off for 0 s operation or configured within a range of 0.1–30 s.
Where immediate fault signalling is required, the relay can operate without an intentional tripping delay. In applications where short-duration supply disturbances are expected, a suitable delay can help reduce unnecessary switching.
The relay also supports selectable ON-delayed or OFF-delayed tripping behaviour, providing additional flexibility for industrial control applications. A 200 ms start-up delay is incorporated into the device's operating characteristics.
Its two changeover contacts are rated at 250 V / 4 A and can be connected to compatible PLC inputs, alarm circuits and motor control equipment.
The CM-PSS.31P is a monitoring and signalling device. It does not replace properly selected short-circuit protection, motor overload protection or other protective equipment required by the installation.
Easy Connect Push-In Terminals and Compact DIN Rail Installation
The CM-PSS.31P uses ABB's Easy Connect Technology, featuring screwless push-in terminals designed to simplify electrical panel wiring.
The spring-clamp terminal system provides secure electrical connections when correctly installed and reduces the need for conventional screw terminal tightening. This is particularly beneficial in OEM machinery and industrial control cabinet assembly.
With dimensions of 85.6 × 22.5 × 103.7 mm, the relay occupies only 22.5 mm of DIN rail width. Tool-free mounting and removal further support efficient installation and maintenance.
Three front-mounted LEDs provide operating status information, while accessible controls allow engineers to configure the phase sequence function and tripping delay. An optional sealable transparent cover can help prevent unauthorised changes to the settings.
Typical Applications
- Three-phase supply monitoring in nominal 380 V AC electrical systems.
- Phase failure detection in industrial motor circuits.
- Phase sequence monitoring for rotation-sensitive machinery.
- Overvoltage supervision in three-phase distribution panels.
- Undervoltage detection in industrial electrical installations.
- Motor control centres and machinery control panels.
- Pump motor supply monitoring.
- Fan and ventilation equipment.
- Compressor control systems.
- Conveyor and material handling machinery.
- Manufacturing and production equipment.
- Industrial electrical distribution boards.
- PLC-based voltage fault monitoring and alarm signalling.
- OEM machinery designed for 380 V AC three-phase supplies.
- Industrial installations requiring fixed voltage monitoring thresholds.
- Compact DIN rail control cabinets with push-in wiring.
