Why Choose the ABB CM-MPS.21S Three-Phase Monitoring Relay?
The ABB CM-MPS.21S is a multifunctional three-phase monitoring relay with neutral monitoring designed to supervise critical electrical conditions in industrial three-phase systems. With ABB order code 1SVR730885R3300, it operates directly from the monitored network across a 3 × 180–280 V AC phase-to-neutral range at 50/60 Hz.
The CM-MPS.21S monitors phase failure, phase sequence, overvoltage, undervoltage, phase unbalance and interrupted neutral. The corresponding threshold values are adjustable, while phase-sequence monitoring can be selected as required. The relay can also be used for monitoring suitable single-phase mains, providing additional flexibility for industrial control applications.
A 200 ms start-up delay and selectable ON- or OFF-delay with an adjustable tripping time of 0 or 0.1–30 s allow the response to be tailored to the application. Two changeover (SPDT) output contacts rated at 250 V / 4 A, screw connection technology and a compact 22.5 mm DIN-rail housing provide straightforward integration into control panels.
Key Advantages
- Multifunctional supervision of critical three-phase supply conditions.
- Monitors phase failure, phase sequence, overvoltage and undervoltage.
- Provides phase unbalance detection for additional supply supervision.
- Includes interrupted neutral monitoring for three-phase systems with neutral.
- Adjustable threshold values enable application-specific monitoring.
- Selectable ON- or OFF-delay with adjustable tripping time.
- Two changeover output contacts provide flexible signalling and control.
- Compact 22.5 mm-wide housing conserves DIN-rail space.
Key Features
- ABB CM-MPS multifunctional three-phase monitoring relay series.
- 3 × 180–280 V AC phase-to-neutral measuring range.
- 180–280 V AC rated control supply voltage, phase-to-neutral.
- 50/60 Hz rated supply frequency.
- Phase failure detection.
- Selectable phase sequence monitoring.
- Adjustable overvoltage and undervoltage monitoring.
- Adjustable phase unbalance monitoring.
- Interrupted neutral monitoring.
- Suitable for monitoring compatible single-phase mains.
- 200 ms start-up delay.
- 0 or 0.1–30 s selectable ON- or OFF-delay.
- 2 c/o (SPDT) relay outputs.
- Screw connection technology with double-chamber cage terminals.
Comprehensive Three-Phase and Neutral Monitoring
Three-phase machinery and electrical systems can be affected by phase loss, incorrect phase rotation, excessive or insufficient voltage, phase unbalance and interruption of the neutral conductor. The ABB CM-MPS.21S combines monitoring of these conditions in one compact device, enabling connected control equipment to respond when the electrical supply moves outside the configured operating limits.
Adjustable thresholds allow the monitoring response to be matched to the installation, while the 200 ms start-up delay supports stable operation following energisation. The selectable ON- or OFF-delay of 0 or 0.1–30 s can help distinguish persistent supply faults from short-duration variations before the output contacts switch.
Typical Applications
- Three-phase motor and machinery monitoring.
- Industrial control and automation panels.
- Phase failure and phase sequence supervision.
- Overvoltage and undervoltage monitoring.
- Phase unbalance detection.
- Interrupted neutral monitoring.
- Pumps, fans, compressors and conveyor systems.
- Industrial power distribution and OEM machinery.
