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Imager Settings for MCC Inspections

Infrared inspections of electrical distribution systems frequently include motor controllers. Proper imager settings and inspection technique are imperative In order to accurately inspect these critical electrical devices.

Industrial motors of all sizes are frequently controlled by remote devices known as motor controllers. Motor controllers are small to large metal-clad devices containing one or more large solenoids that control starting/stopping, motor speed, and rotation direction.

Motor controllers often contain a number of electrical devices operating at widely differing temperatures. These devices include control circuits, transformers, fuses, circuit breakers, contactors, thermal overloads, and circuit conductors. The temperature of these devices can range over hundreds of degrees.

When performing an infrared inspection, setting a thermal imager’s controls to encompass the whole motor control in a single view is not recommended as significant problems can be overlooked. For best results, we recommend the following:

• Ensure that subject motor controller is under load
• Image from a distance that permits viewing only of the subject controller components.
• Perform inspection in direction of line to load side of motor control circuit
• View subject components individually
• Adjust level/gain settings to optimize image for each component inspected
• Compare features of similar components to each other, noting inexplicable differences

For controllers with multiple contactors, it will be necessary to inspect each contactor individually while under load. Be sure to allow sufficient time for subject contactor to achieve running temperature.