Electrical maintenance is a subject almost as broad and diverse as the opinions of those who sell it, perform it, and depend upon it to keep the lights on. The definition of maintenance has changed over time due to changing manufacturer’s recommendations, ideas from self-promoting industry groups, the influence of service providers, and the constraints of access to perform what we commonly call preventive maintenance.
Webster’s defines “preventive” as “something that prevents” and “maintenance” as “the act of maintaining, the upkeep of property or equipment.”
Dictionary.com defines “preventive maintenance” as “To bring down a machine for inspection or test purposes.”
A common ironic form of preventive maintenance goes like this. Actions are performed upon a machine at regularly scheduled intervals to ensure that the system remains in an unusable state. This so-called preventive maintenance is all too often performed by field servoids who don’t know what they’re doing; such maintenance often induces problems or otherwise results in the equipment remaining unusable for an indeterminate amount of time.
Ouch, that hurts. Fact is, there is often a difference between what we believe is being done and what is actually being done to mission critical electrical infrastructure. Over the years, our attitudes have changed in part as the mission of our facilities has become more directly related to the success of our businesses and the balance sheet.
The figure (see figure 1) shows the progression of our attitudes toward maintenance. No maintenance certainly reduces downtime until a cascading failure occurs due to lack of attention. Reactive maintenance is the product of no maintenance, “Don’t fix it if it ain’t broke,” and is no longer part of the mission-critical lexicon.
Preventive maintenance is the application of manufacturer’s recommendations and industry best practices. The word preventive is subject to tempering (or tampering) in this case. Most comprehensive “preventive maintenance” programs do not preclude a failure. They do, however, improve the odds of discovering and correcting a deteriorating condition in order to prevent an impending failure.
Proactive maintenance is the application of best practices taking full advantage of technology. One such technology, which has changed the way we maintain electrical infrastructure, was the discovery of infrared energy. In 1800, Sir William Herschel was engaged in building telescopes when he wondered if the different colors of light that passed through a prism had different temperatures. He devised an experiment to support his hypothesis and confirmed that the temperatures of the color spectrum of light did indeed increase from violet to red. He further noted the temperature increased further just beyond the red spectrum (infrared).
As the mission of facilities changed, so did approaches to maintenance. Not maintaining systems or simply reacting to failures are no longer options as preventive maintenance morphs into a more proactive posture.
What technology could be more proactive then thermal imaging? Developed for the U.S. military in the late ’50s and early ’60s by Texas Instruments & Hughes Aircraft, the first IR instruments were used primarily to detect the presence of opposing forces at night or under smoky battlefield conditions. It wasn’t long before other uses were developed.
The use of thermal imaging to detect abnormal heat in electrical gear has long been standard accepted best practice. A qualified operator with the right equipment stands in front of energized electrical switch gear with all shields removed and the gear under full normal building load. The resulting IR scan will reveal an image of the heat associated with load. A trained thermographer must interpret the image as normal or abnormal.
Should the operator detect an abnormal level or pattern of heat on cable terminations, buss joints, or other such connections, a still IR image of the problem area would be taken. This IR image is mounted in the report adjacent to a black-and-white control photograph of the same joint or area for identification purposes. A narrative describes what the thermographer believes the problem to be (loose connection, overload, etc.). Theoretically, this procedure is done annually prior to maintenance shut down windows so that identified problems may be addressed.
Pretty simple, really, except for the hazard of arc flash. No longer may the thermographer stand in harm’s way without full protection of PPE (personal protective equipment) commensurate with the class of hazard identified at the point in the system being scanned (see figure 2). NFPA 70E and OSHA requires that arc-flash hazard labels be affixed to all access points in electrical gear and that any person working in the vicinity with the covers or doors open while the gear is energized be appropriately attired, including the thermographer. The cost of IR scans has gone up and productivity has gone down.