Diagnostic method for predicting maintenance requirements in rotating equipment

A diagnostic method for predicting maintenance requirements in rotating equipment normally operating in loaded and unloaded conditions, the method including the following steps;

• coupling a sensor to apparatus associated with said rotating equipment, said sensor being responsive to vibration in said apparatus to generate an electric signal;
• obtaining a load signal from apparatus associated with said rotating equipment which is indicative of whether the rotating equipment is loaded;
• calculating a range of average maximum and average minimum electric signal readings over a pre-selected sampling time interval for rotating equipment in a loaded condition;
• calculating a range of average maximum and average minimum electrical signal readings over a pre-selected sampling time interval for rotating equipment which is not loaded;
• calculating the natural log of the ratio of an average loaded to average unloaded range value to define a condition index;
• periodically displaying the condition index over an extended maintenance period of time, a maintenance inspection being required when the condition index falls below a predefined threshold.