Product Overview

The ABB CM-MPS.21S, identified by order code 1SVR730885R3300, is a multifunctional three-phase monitoring relay designed to provide comprehensive protection for electrical power systems and industrial machinery. Operating as a critical diagnostic component within the AC500 range and broader DCS architectures, this True RMS monitoring device evaluates phase parameters with extreme precision. It is specifically engineered to detect phase failure, phase sequence, overvoltage, undervoltage, and phase unbalance. By providing real-time oversight of the power supply quality, the CM-MPS.21S prevents costly motor damage and equipment degradation, serving as a first line of defense in automated industrial environments.

Technical Architecture and Hardware Metrics

• Model Designation: CM-MPS.21S

• Global Order Number: 1SVR730885R3300

• Measurement Principle: True RMS (Root Mean Square) monitoring

• Protection Functions: Phase failure, Phase sequence, Over-/Undervoltage, Phase unbalance

• Net Weight: 0.12 kg

• Physical Dimensions: 1.5 x 18.6 x 12.8 cm

• Mounting Type: DIN rail (Snap-on)

• Connection Technology: Push-in or screw terminals (Variant dependent)

• Production Origin: Sweden

• Tariff Classification: HS 8537101190

• System Compatibility: AC500 / Distributed Control Systems

The module features a slim 22.5 mm width housing, maximizing cabinet space efficiency. Its True RMS measurement capability allows it to accurately monitor distorted wave forms, making it ideal for modern industrial networks where non-linear loads and variable frequency drives are present.

Strategic Industrial Implementations

The 1SVR730885R3300 relay is a versatile safety asset utilized in various mission-critical sectors:

• Motor and Pump Protection: Preventing phase reversal or single-phasing in industrial motors, which can cause catastrophic overheating and mechanical failure.

• DCS Power Supervision: Acting as a localized diagnostic node within an AC500 PLC setup to monitor the stability of the incoming supply before distributing power to sensitive I/O.

• HVAC and Compressor Control: Ensuring correct phase sequence for three-phase compressors to prevent reverse rotation and internal damage.

• Material Handling and Elevators: Providing a safety interlock that prevents machinery from starting under improper voltage conditions or phase unbalance.

FAQ

Q: What is the benefit of True RMS monitoring in the CM-MPS.21S?

A: True RMS measurement allows the relay to accurately calculate the effective voltage even when the power supply is distorted by harmonics or noise, which is common in environments with power electronics.

Q: Does the 1SVR730885R3300 require a separate neutral connection?

A: This specific "S" version (CM-MPS.21S) can be used in three-phase networks with or without a neutral conductor, offering high flexibility for different electrical grid configurations.

Q: Can this monitoring relay be used with an Ethernet router?

A: While the relay itself is a hardware protection device, its status signals can be integrated into a DCS or AC500 PLC system, which then transmits diagnostic data through an Ethernet router for remote monitoring.

Q: How does the module handle temporary voltage dips?

A: The device features adjustable time delays for overvoltage and undervoltage tripping, allowing it to ignore harmless, momentary voltage fluctuations and prevent nuisance tripping.

Q: Is the phase sequence monitoring feature mandatory or can it be disabled?

A: Depending on the specific configuration settings on the front-facing potentiometers, you can set the device to monitor or ignore the phase sequence, depending on whether the connected load is rotation-sensitive.