Vibro-meter VM600 MPC4 mechanical protection card

The MPC4 machinery protection card is the central element in the VM600 series machinery protection system (MPS), from Meggitt’s Vibro-Meter® product line. This very versatile card is capable of measuring and monitoring up to four dynamic signal inputs and up to two speed inputs simultaneously.

The dynamic signal inputs are fully programmable and can accept signals representing acceleration, velocity and displacement (proximity), among others. On-board multichannel processing allows measurement of various physical parameters, including relative and absolute vibration, Smax, eccentricity, thrust position, absolute and differential housing expansion, displacement and dynamic pressure.

Digital processing includes digital filtering, integration or differentiation (if required), rectification (RMS, mean value, true peak or true peak-to-peak), order tracking (amplitude and phase) and measurement of the sensor-target gap.

The speed (tachometer) inputs accept signals from a variety of speed sensors, including systems based on proximity probes, magnetic pulse pickup sensors or TTL signals. Fractional tachometer ratios are also supported.

The configuration can be expressed in metric or imperial units. Alert and Danger set points are fully programmable, as are alarm time delay, hysteresis and latching. The Alert and Danger levels can also be adapted as a function of the speed or any external information.

A digital output is available internally (on the corresponding IOC4T input/output card) for each alarm level. These alarm signals can drive four local relays on the IOC4T card and/or can be routed using the VM600 rack’s Raw bus or Open Collector (OC) bus to drive relays on optional relay cards such as the RLC16 or IRC4.

The processed dynamic (vibration) signals and speed signals are available at the rear of the rack (on the front panel of the IOC4T) as analog output signals. Voltage-based (0 to 10 V) and current-based (4 to 20 mA) signals are provided.

The MPC4 performs a self-test and diagnostic routine on power-up. In addition, the card’s builtin “OK system” continuously monitors the level of signals provided by a measurement chain (sensor and/or signal conditioner) and indicates any problem due to a broken transmission line, faulty sensor or signal conditioner.

An LED indicator on the MPC4 front panel indicates whether a processing or hardware error has occurred. Six additional LEDs (one per input channel) indicate whether the OK System has detected a fault and whether an alarm has occurred on the channel.

The MPC4 card is available in three versions: a “standard” version, a “separate circuits” version and a “safety” (SIL) version, all of which function as a card pair using a corresponding IOC4T input/ output card.