Our last MCA data analysis tip stated that it is not uncommon, for new users that begin a MCA motor testing program, to have between 10-30% of motor systems tested to exhibit some alarm condition. It is important to note that a motor system exhibiting an alarm condition should not be condemned (or the motor replaced), if the test was performed from the motor control center (output of the motor starter or motor drive). Motor connections and cables between the test point and the motor itself may be the root-cause of the alarm.
Therefore, the next step is to perform another test at the next connection point, whether a disconnect or at the motor itself, with incoming phase leads disconnected. If the alarm condition clears, then the problem is upstream of the test point. If the alarm persists then it is the motor. Lastly, non-repeatable test results should be considered suspect and investigated further.