EPRO MMS6120 Dual Channel Overspeed Protection Monitor (9100-00002C-08)

The EPRO MMS6120 (ordering code 9100-00002C-08) is a dual-channel overspeed protection monitor designed to provide reliable overspeed protection for steam turbines, gas turbines, and other critical rotating machinery. It is part of the MMS6000 series and complies fully with API 670 requirements for overspeed protection systems. The module accepts speed signals from passive magnetic pickups or active eddy current sensors (e.g., PR642x with CONxxx converters). Two independent channels continuously monitor speed and compare it against user-adjustable setpoints. If the speed exceeds the trip level, each channel activates a dedicated relay, which can be used to trigger emergency shutdown actions. The module also provides scalable analog outputs for remote speed indication.

Key Features

• Two Independent Channels: Fully redundant speed measurement and trip logic to meet safety requirements.

• Wide Input Compatibility: Accepts signals from magnetic pickups (MPU) or eddy current sensors (after signal conditioning).

• Adjustable Setpoints: Independent trip levels for each channel, with adjustable hysteresis and time delays.

• Voting Logic: Configurable 1oo2 or 2oo2 voting for trip relays to balance safety and availability.

• Analog Outputs: Two isolated 4-20 mA outputs proportional to speed for DCS/SCADA interface.

• API 670 Compliant: Meets all requirements for overspeed protection devices, including response time, accuracy, and self-test features.

Technical Specifications

• Input Channels: 2

• Input Signal Types: MPU (0.5 to 30 Vpp), eddy current (via CONxxx)

• Frequency Range: 1 Hz to 20 kHz

• Accuracy: ±0.1% of full scale

• Trip Relays: 2 per channel, DPDT, 250 VAC / 5 A

• Analog Outputs: 2 x 4-20 mA, max load 600 Ω

• Response Time: < 40 ms (from overspeed to relay trip)

• Power Supply: 24 VDC (18-36 VDC) via backplane

• Operating Temperature: -20°C to +65°C

• Mounting: MMS6000 rack system

• Certifications: CE, UL, SIL2 capable (per IEC 61508)

Applications

The MMS6120 is essential for protecting high-speed rotating machinery from catastrophic overspeed events. It is used in steam turbines, gas turbines, hydro turbines, compressors, and large pumps. In power plants, it ensures that turbines shut down safely if governor control fails. In industrial applications, it prevents mechanical disintegration due to excessive speed.

Integration and Configuration

The module plugs into an MMS6000 rack with dedicated power supply and communication modules. Configuration is done via front-panel DIP switches or through the MMS6850 communication interface. Setpoints, hysteresis, and voting logic are easily set. The module performs continuous self-diagnostics, and any fault is indicated via front LEDs and a health relay.

Reliability and Environmental Compliance

Designed for safety-critical applications, the MMS6120 features redundant measurement paths and comprehensive self-testing. It meets IEC 61000-4 EMC standards and is tested for vibration and temperature extremes. The module is CE marked and can be used in SIL2 applications with appropriate external wiring.

With its high accuracy and fast response, the EPRO MMS6120 overspeed protection monitor ensures that critical rotating machinery operates within safe speed limits, preventing costly damage and downtime.