The secret costs of electric motors

Stanton McGroarty explores the 3 steps to fix whatever is killing your power.

By J. Stanton McGroarty, CMRP, CMfgE

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Electric motors are typically nameless orphans, unloved and mostly unnoticed until they stop running. When they quit, they become the center of postmortem attention for exactly as long as it takes to replace them. After that, their anonymity drops beyond the orphan level as they are chucked into dumpsters or, if they’re lucky, recycling bins. The question of an autopsy seldom comes up.

The throwaway treatment isn’t due to the motors’ low cost. They are expensive. The price, delivered and installed, of anything over 50 hp will be well into five figures. Smaller units represent expenses that would cause a major stir in anyone’s household accounts. The total cost of changing motors in many businesses is huge, and largely uncontrolled.

Two factors contribute to the orphan status of motors and their cost. First, the total cost of electric motors is usually no one group’s responsibility. Second, the replacement cost of motors, when they have failed, is usually dwarfed by the economic impact of the production or other losses that are occurring because of the failure. The first factor is pretty subtle. Purchase cost of the first motor in an installation is usually buried in the bill for OEM equipment. Maintenance and replacement cost is aggregated into maintenance budgets and then departmental overhead numbers. Utility cost is usually aggregated plant-wide, or at least by department. Later, when a failure has occurred, the flurry of cost and activity surrounding the replacement obscures the motor’s cost.

The upshot of these two factors is that a steady stream of replacement motors flows through many factories with nobody taking notice of its financial impact. Once a particular installation begins to burn up motors, the cost becomes a budget item, business as usual. Motors that should run for 10 or 20 years are often replaced every year or six months without anyone taking particular notice. Maintenance workers who purchase and stock replacements become heroes when they restore productivity.

J. Stanton McGroarty, CMfgE, CMRP, is senior technical editor of Plant Services. He was formerly consulting manager for Strategic Asset Management International (SAMI), where he focused on project management and training for manufacturing, maintenance and reliability engineering. He has more than 30 years of manufacturing and maintenance experience in the automotive, defense, consumer products and process manufacturing industries. He holds a bachelor of science degree in mechanical engineering from the Detroit Institute of Technology and a master’s degree in management from Central Michigan University. He can be reached at smcgroarty@putman.net or check out his .

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Three steps can help any plant identify and solve excessive electric motor cost. First, see if there is an opportunity for important savings. A simple vendor analysis can tell how many of what kinds of motors are frequently replaced. The vendor approach is helpful because it brings cost information with it. Double motor costs for an approximation of shipped and installed cost. Motor vendors can also be an important resource in the second step, finding out what is causing the motors to fail. It is always smart to save motors for analysis before scrapping and to document the failure modes. To develop a snapshot of what is going on at a plant, though, discussion with maintenance technicians and operators can deliver much of the failure mode information. Organize the discussion around the list of specific motors that have been replaced from the first step. A limited number of failure modes will drive premature failures; over- or under-lubrication, contamination, misalignment, overloading, excessive start/stop cycling, to name a few, can be readily identified. The third step is, of course, solving the problems that are identified.

Sometimes training and the establishment of improved operating procedures can solve the big problems. Lubrication and alignment are often responsive to these. Some problems, though, such as overloading, contamination, and over-cycling, may indicate opportunities to improve the choice of motors in problematic applications. Vendors are, of course, available to help here. All will work with plant staff on specific motor choices. Some also offer programs to survey the whole fleet of motors in a large plant and recommend improved applications. Recent changes in motor specifications and designs make this a good option for industries with motor contamination problems, such as food and mining.

The bottom line is that, if you have a motor problem, the financial opportunity from solving it is probably substantial. Moreover the problem identification won’t be rocket science and a lot of low-cost or no-cost resources would love to help with the solution. If you don’t have the time, a summer student can probably do it.

Read Stanton McGroarty's monthly column, Strategic Maintenance.

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