Are You Smarter Than Your Electric Motors?

The General System Limit for voltage Total Harmonic Distortion (THD) is 5%.

According to NEMA MG-1 the motor should not be run if phase-to-phase voltage imbalance is greater than 5%.

A Polarization Index test must be temperature corrected.

Cracked or broken rotor bars at the end ring of a squirrel cage induction motor will cause a reduction in reflected impedance resulting in a lower average inductance as measured from the stator windings.

A variable frequency drive, connected to a 60 Hz distribution system, is supplying a 37 Hz output frequency to a squirrel cage induction motor. When performing current signature analysis for rotor evaluation of the squirrel cage induction motor, what would be the peak frequency of the current spectrum?

A fully loaded squirrel cage induction motor exhibits a 10% impedance imbalance and a 10% current imbalance, which fault zone is most likely the problem?

Reactive Maintenance is characterized by run to failure practices. Preventive maintenance is characterized by periodic or time based practices. Predictive maintenance is characterized by practices based on equipment condition.

While viewing the current spectrum of a fully loaded squirrel cage induction motor you notice that the pole-pass frequency (Fp) sideband amplitude is 42 db. What fault zone would you be concerned with?

In “Principles of Large AC Motors” by the Electrical Apparatus Service Association (EASA) it is recommended to rotate the shaft monthly.

As stated in the EASA literature Understanding Energy Efficient Motors, the number one misconception about energy efficient motors is that “An oversized motor is less efficient.”