EPRO MMS6350 Modules: MMS6350/DP Digital Overspeed Protection System —

Technical Dossier

Product Details And Specifications

EPRO MMS6350 Series: Comprehensive Module Range and Technical Overview

The EPRO MMS6350 series is a dedicated line of digital overspeed protection systems engineered for critical rotating machinery in heavy industrial environments. Deployed extensively in petrochemical plants, nuclear power stations, offshore platforms, and oil refineries, the MMS6350 series provides turbine, compressor, and pump shaft overspeed detection with trip-relay outputs conforming to SIL 2 / IEC 61508 functional safety requirements. The series is manufactured by EPRO GmbH (a Metso Automation / Baker Hughes company) and represents the digital successor to the earlier MMS3000 and MMS6000 analog protection families. Its modular rack-based architecture allows integration into existing DCS/SIS backplanes without full system replacement, making it a preferred choice for brownfield lifecycle extension projects across the global process industry.

The Evolution of MMS6350 Architecture

EPRO's machine protection portfolio evolved through three distinct generations. The first generation (MMS3000 series, 1980s–1990s) relied on analog signal conditioning with discrete relay logic, offering limited diagnostic transparency and no digital fieldbus connectivity. The second generation (MMS6000 series, mid-1990s to early 2000s) introduced microprocessor-based signal processing and RS-485 serial communication, enabling basic SCADA integration but still constrained by proprietary protocol stacks.

The MMS6350 series (introduced circa 2005) represents the third generation: fully digital, with on-board DSP for real-time frequency measurement, configurable trip thresholds via software, and support for Modbus RTU / Profibus DP fieldbus protocols. The MMS6350/DP variant specifically integrates a Profibus DP communication interface, enabling direct integration into Siemens PCS 7, ABB 800xA, and Honeywell Experion DCS environments. Backward compatibility with MMS6000-series sensor wiring (eddy-current probes, magnetic pickups) was preserved, reducing retrofit costs. As of 2024, the MMS6350 series has entered the mature/end-of-active-production phase; EPRO continues to supply spare modules through authorized channels, and third-party MRO suppliers such as DriveKNMS provide lifecycle extension support for installed bases.

MMS6350 Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified MMS6350 series module range, classified by functional category. Each model is a discrete, field-replaceable unit designed for 19-inch rack or DIN-rail mounting.

Overspeed Protection Modules

• MMS6350/DP: Digital overspeed protection module with Profibus DP interface; configurable 1-of-2 or 2-of-3 voting logic.
• MMS6350/MB: Digital overspeed protection module with Modbus RTU interface; RS-485 serial communication, 9600–115200 baud.
• MMS6350/SO: Standalone overspeed protection unit; no fieldbus, hardwired trip relay outputs only, SIL 2 rated.
• MMS6350/TR: Triple-redundant overspeed protection module; 2-of-3 voting architecture for turbine critical trip circuits.

Signal Conditioning & Input Modules

• MMS6350/SC: Speed signal conditioning module; accepts magnetic pickup (MPU) and eddy-current probe inputs, 0–20 kHz range.
• MMS6350/AI: Analog input module; 4–20 mA process variable inputs for auxiliary parameter monitoring (temperature, pressure).
• MMS6350/DI: Digital input module; 24 VDC discrete inputs for external interlock and permissive signals.
• MMS6350/DO: Digital output module; relay and transistor outputs for trip, alarm, and status signals.

Communication & Gateway Modules

• MMS6350/GW: Protocol gateway module; bridges MMS6350 internal bus to Modbus TCP/IP Ethernet for SCADA integration.
• MMS6350/PN: PROFINET IO adapter module; enables MMS6350 rack integration into PROFINET-based control architectures.
• MMS6350/FF: Foundation Fieldbus H1 communication module; for process plants using FF-based DCS infrastructure.

Power Supply Modules

• MMS6350/PS24: 24 VDC redundant power supply module; dual-input with automatic switchover, 10 A output capacity.
• MMS6350/PS48: 48 VDC power supply module; for installations with 48 V DC bus infrastructure.
• MMS6350/PSR: Power supply redundancy module; hot-swap capable, monitors both supply rails and generates fault alarm.

CPU & Rack Infrastructure

• MMS6350/CPU: Central processing unit module; hosts configuration firmware, event log (10,000 entries), and fieldbus master function.
• MMS6350/RK8: 8-slot rack chassis; passive backplane with dual power bus and module keying for incorrect-insertion prevention.
• MMS6350/RK16: 16-slot rack chassis; expanded I/O capacity for large turbine protection systems.

Sourcing Hard-to-Find & Obsolete MMS6350 Parts

Quality Control for the MMS6350 Range

The MMS6350 series presents specific test challenges due to its integrated backplane communication bus, DSP-based frequency measurement core, and SIL 2 trip relay circuits. DriveKNMS applies a structured verification protocol to all MMS6350 units prior to dispatch. Each module undergoes: (1) visual inspection for PCB damage, connector wear, and capacitor condition; (2) powered functional test at rated supply voltage with simulated MPU/eddy-current probe input signals across the full 0–20 kHz measurement range; (3) trip relay output verification at configured threshold setpoints; (4) fieldbus communication test (Profibus DP or Modbus RTU as applicable) confirming correct node addressing, cyclic data exchange, and diagnostic telegram response; (5) 48-hour burn-in soak at 40°C ambient to screen for latent component failures. Test records are retained for 5 years and are available to customers as part of the quality documentation package.