The XM-120 Eccentricity module is a 2-channel eccentricity monitor. It is a member of the Allen-Bradley™ XM® Series, a family of DIN rail mounted condition monitoring and protection modules that operate both in stand-alone applications or integrate with Programmable Logic Controllers (PLCs) and control system networks.
Eccentricity is the measure of the amount of bow in a rotor. The lower the eccentricity value the more straight the shaft. Rotor bow can be a fixed mechanical bow, or it can be a temporary bow caused by uneven thermal heating or simply by the weight of the rotor (gravity bow).
The Eccentricity module is suitable for virtually all types of rotating and reciprocating machinery where rotor bow must be measured prior to or during startup. It accepts input from non-contact eddy current probe systems to provide peak-to-peak eccentricity, maximum instantaneous DC voltage (max gap), minimum instantaneous DC voltage (min gap), and instantaneous DC voltage (gap) measurements. In addition to the transducer inputs, the module can accept one tachometer input to provide speed measurement, which can, ifdesired, be used to disable eccentricity alarms after startup.
