Motor Testing Methods & Procedures for Zero Downtime

Because complete motor failure often starts as small faults in components within the motor, different motor testing methods analyze and/or trend the condition of those components to determine when proactive repair needs to be done.

Many motor diagnostic instruments are marketed as ‘motor testers’, while their function may solely provide you with motor component parameter measurements rather than the condition of these components and the motor’s health overall.

A more comprehensive approach can better preserve the lifespan of your motor system, quickly diagnose and troubleshoot problem motors, helping you avoid sudden motor failure, as well as the potential downtime or extensive repairs from compounding issues as the motor continues to operate.

1. Voltage Balance

An unbalanced voltage between phases impacts the motor’s operation. The effects include an unbalanced current, a minor reduction in full-load speed and smaller locked rotor and breakdown torques given the application. Plus, these voltage issues lead to increased operating temperatures — a 3.5% unbalance results in a 25% temperature fluctuation.

In order to obtain a true condition of a motor winding, one must view all of the motor circuit components, including resistance, impedance, inductance, phase angle and insulation resistance.

To prevent motor derating, use precision equipment like the ALL-TEST PRO 7™ which can detect the subtlest imbalances of impedance unbalance, calculate resistance, inductance and phase angle along with insulation resistance with a 3-minute automated test that requires no further analysis nor interpretation.

2. Winding Insulation Limitations and Ground Fault Detection

Monitoring the resistance levels and condition of the winding insulation is a critical step in motor testing and failure prevention.

While average Megohmmeters can determine insulation to ground integrity, it can’t determine the health of the entire system. These tools can’t read faults past the ground-wall insulation. They can only detect paths between the stator core and conductors adjacent to the component.

For this reason, it’s better to use a method of motor testing that measures the stator, rotor and motor connections as well as the windings between turns. This combination assures no internal abnormalities are missed.

The condition of any electrical device’s insulation system is required for safe operation. Megohmmeters use high voltages to locate weaknesses in the groundwall insulation but provide little if any information regarding the overall health of the insulation system and completely ignores the winding insulation system – which accounts for > 80% of stator electrical failures.

By performing a series of tests designed to thoroughly test the entire winding, conductors and groundwall insulation, Motor Circuit Analysis™ (MCA) is the only technology that exercises both the groundwall and winding insulation systems. MCA™ finds developing faults between turns anywhere in the winding system very early in the P-F curve. 

3. Contamination and Motor Cleanliness

The cleanliness of a motor is often overlooked in a motor maintenance program. Contamination is frequently the cause of premature motor failure because it inhibits the motor’s ability to cool itself, degrading the insulation quicker. A common cause of contamination is over greasing of the bearing which goes undetected usually until the motor fails.

Utilizing Motor Circuit Analysis™, you can detect contamination issues on the windings and take appropriate steps to preserve the insulation’s condition.

4. Surge Testing

Surge testing produces high voltage pulses that can be destructive to the motor if not performed correctly. Surge testing only finds faults in the first couple of turns.

The instruments are not portable. Therefore, consider choosing an instrument that is field portable and introduces lower voltages through the entire system, like one of ALL-TEST Pro’s offerings that measure with harmless low voltage sinusoidal AC signals which is a faster & safer approach for installed motors, and as an alternative to bench testing motors.

Motor Testing Made Easy With ALL-TEST Pro

While there are plenty of tools like temperature sensors, Megohmmeters and oscilloscopes used to approach motor testing,  ALL-TEST Pro products allow you to perform multiple diagnostic procedures with one lightweight device.

ALL-TEST Pro specifically designs motor testing tools to give you a fast, accurate analysis of your motor’s health in under 3 minutes!