Why Test Motors?

Because motors fail. Based on statistical data compiled by the Electric Power Research Institute (EPRI), 47% of motor failures are due to electrical faults/failures. The 47% can be further broken down into rotor problems (10%) and winding problems (37%). The other 53% of failures will be mechanical faults.

Winding defects can occur due to insulation age, contamination, power surges, thermal overload, damaged wire/materials, vibration, and other causes. They begin as energy crossing an insulation fault (such as moisture or contamination), which isolates at least one turn. This generates additional stress and heat across the defect, which progresses until an arc is drawn and the winding fails.

About Winding Faults

Winding Fault

There are four basic types of winding faults.

  • Between turns in a coil
  • Between coils in a phase
  • Between coils in different phases
  • Between a coil or phase and ground

Only about 17% of electrical faults begin as a conductor to ground fault. The other three fault types may or may not propagate into a ground fault as the failure becomes advanced. The short-term result of these faults is reduced efficiency and higher operating costs. Symptoms include higher operating temperatures, nuisance tripping, and reduced motor life. As faults advance, the ability of the motor to drive the load may decrease. The longer term result is always motor failure.

Facts about Winding Faults

  • Usually start in the end turns of windings

    • Greatest stresses
    • Insulation is weakest

  • They start small and escalate over time
  • They always end in failure
  • Contributing factors to failure

    • Overloading
    • Frequent start/stop cycling
    • Vibration
    • Contamination
    • Age, Heat, & Motor Drives

Save Money, Make Money

Test Value Static Display

Just finding one of the faults mentioned above can save your organization countless hours of downtime and thousands of dollars in savings. 

Perform a simple Test Value Static (TVS™) in just a few minutes. Use this as an initial reference as a motor specific parameter value, and to confirm the health of an induction motor. Subsequent test results can be immediately compared to the reference TVS™ to instantly show developing problems or changes with the stator or squirrel-cage rotor.  A reference test can be established from the starter or motor drive, making it easy to detect changes with connections and cables, along with the motor. No need to access computer software while in the field!

Since TVS™ is a motor specific parameter it can be used as a Reference test for that particular motor.  The results can be stored.  Additionally, if you have multiples of the exact same motor (manufacturer/type) then the Reference test can be used for all of them. This makes incoming inspection of motors whether new or repaired very easy to perform as it only takes a few minutes per motor.