Vibro-Meter TFM677 Monitoring Module

The TFM677 is a tracking filter module in the Vibro-Meter VM600 series Mechanical Protection System (MPS) produced in Switzerland.

The Vibration TFM677 module works in coordination with other monitoring equipment to track and ensure the status of the operating characteristics of mechanical equipment.

Automatically follows the selected shaft order (e.g., 1×, 2×, gear mesh, blade pass) as speed changes, ensuring the filter’s center frequency scales with RPM.

Maintains lock during acceleration, deceleration, or transient speed shifts.

Narrow relative bandwidth (± 0.5 % of order) for maximum sensitivity to small changes.

Wider fixed-Hz options (up to 200 Hz) to include sideband content or reduce noise sensitivity.

Choice of Tchebychev (sharp cutoff) or Butterworth (flat response) topologies.

Provides per-order amplitude (true RMS or peak) and phase (0–360°) with high accuracy.

Supports phase-based diagnostics (e.g., balancing, misalignment detection, gear fault localization).

Two fully programmable thresholds (Alert, Danger) direct on the card.

Thresholds can be specified in engineering units (e.g., mm/s, mils) or as a percentage of full scale.

Speed-proportional thresholds available to reduce false alarms at low RPM.

Configurable time delays (1–99 s) and hysteresis.

Standard VM600 6U rack form factor; plugs into any available slot.

Supports hot insertion and removal under power—no system shutdown required.

Easily replaced during maintenance to minimize downtime.

Designed to withstand harsh environments: wide temperature range, high humidity tolerance, shock, and vibration immunity per IEC standards.

Standard IP40 rating; optional protective enclosures available for higher ingress protection or explosion-proof requirements.

Communicates via Raw Bus and OC Bus on the VM600 backplane for alarm routing and data exchange.

Works alongside other VM600 modules (e.g., CMC16 condition monitoring cards, MPC protection cards) within a single rack.

Compatible with VibroSight software for configuration, trending, and advanced analytics

An unmanned offshore platform houses a 20 000 HP gas‐compression train, including a two‐stage integrally geared compressor running at ~7 200 RPM. Gear mesh frequencies (GMFs) and their sidebands are primary indicators of impending tooth wear or misalignment—but the complex gearbox ratio meant GMF sat around 120 000 CPM (2 000 Hz), buried in broadband noise.

Two TFM677 cards (one per stage) were slotted into a VM600 rack installed in the platform’s machinery shelter.

Each card was set to track the exact gear-mesh order (e.g., 25× or 35× running speed, depending on stage), with a narrow ± 1 % bandwidth to include essential sidebands.

Alert and Danger thresholds were defined in mils (peak) rather than simply RMS, to suit the OEM’s gearbox fault criteria.