The multi-technology approach to motor diagnostics means you are utilizing different testing technologies that will complement and validate each other. If you don’t believe this, read this case where condition monitoring was performed for an Italian Paper Manufacturer and both vibration analysis and electrical signature analysis was used to confirm broken rotor bars in a motor that drove a fan responsible for clearing fumes (ensuring the safety of workers in the manufacturing facility).
Let’s say your vibration technician suspects a possible rotor problem in a critical application, but the cost to replace the motor means a shutdown of production, and the motor’s cost is small compared to the incurred costs of the shutdown.
In a situation like this, many people would be reluctant to make the call for replacement – especially if the diagnosis is wrong, the cost is very high. Therefore, this motor may be run to failure, due to the uncertainty of the diagnosis. In this case, to put the multi-technology approach into practice! Use the Electrical Signature Analysis (energized testing) to confirm or rule out the preliminary findings (bad rotor for example).
If the shaft of the installed motor can be turned or the load quickly disconnected, then a Motor Circuit Analysis test (de-energized test) can be performed to assess the condition of the rotor, stator, and connections. By utilizing the multi-technology approach, you will have more confidence in your findings and a greater degree of certainty that you have determined the real fault(s).