Motor Repair Horror – Editorial

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There are times when I think I can no longer be surprised by some of the information coming out from the motor repair industry, then the ‘leadership’ makes sure to prove me wrong.

Over the past week a set of articles was brought into my office and placed so that they would attract my attention. I believe the purpose was to see how I would react when I read the headlines of articles explaining how balancing and vibration specifications are useless, or weird ways of testing motors for VFDs, or new winding incinerators that have settings guarantying holding motor core temperatures at 800F. You know, all those things that I have said are happening that these companies have been pushing back claiming they are not.

Talk is cheap – then you people put horrible practices into written recommendations!?!  Really?

Between recommended industry practices like these and industry ‘certifications’ that either use easy-to-pass tests to the shop or you pass if you are using specific products, no wonder the average motor repairs last only 50% of new! It isn’t because other components are worn out, that’s for sure. I guess I am even more disturbed when information is provided to help the repair centers to explain to their victims that good practices aren’t necessary. Think I’m kidding? In one industry-specific rag article on ‘tight vibration specifications being too expensive,’ the statement at the end of the article is: “…service centers should be on the lookout for ‘tight’ vibration acceptance requirements. Be prepared to work with your customer to ensure a cost effective and realistic approach to setting motor acceptance criteria.” The aim, of course, is that the motor ‘lasts through the warranty period,’ which is one year by the industry definition.

If I’m getting you upset – good. The industry has managed to shock me with BS once again! How are they getting away with it? Do they think their customers are stupid? I have always ensured that my clients, customers and friends are as educated as I can so that they can see through this type of activity. How are you educating yourself on proper motor repair practices? After all, aren’t electric machines critical components of your operations?

Would you put your family in a car where the brakes receive the same care and tolerance as your electric motor repair?

But my repair shop isn’t doing that to me, is it? OK, when was the last time you inspected your repair shop and reviewed their practices to make sure that they are following your recommendations. Or, if you have a lot of electric machines and you don’t have a repair specification – what are you thinking? Because electric machines are becoming more precise and use higher quality materials, the average practices of the past aren’t even close to good for modern machine tolerances or for the survivability of a machine in newer electrical and mechanical environments. Yet, that is what you are receiving. I did an article in 2006 on how reliability, maintenance and repair practices have changed over the past century and the surprise was that they have not while technology continues to move forward in machines, materials and operating conditions.  Since 2006 this has not changed in a vast majority of the service industry.

Instead of the industry investing in improvement, more work is being done to provide these organizations with methods and papers to convince the motor owner that poor quality is acceptable.

On all fronts, I have seen a great many machines with original tolerances, electrical, vibration and mechanical, well outside of industry specification. I have seen brand new motor rotors where the balance is way, way out of minimum tolerance. The response that ‘but it is new,’ or ‘that’s the way the manufacturer’ intended is NOT an excuse for providing horrifically bad motor repair. I am pretty sure the original designer intended for specifications to be met, most of the time.

Howard W Penrose, Ph.D., CMRP
The MotorDoc

Balancing and Vibration Asset Health Impact

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An item in a recent electric motor industry repair rag (trade newsletter) spent time and two pages explaining to electric motor repair companies how to convince their customers that poor balancing and vibration practices were acceptable. The statements made within the article were absolutely FALSE. Vibration and, in particular, unbalance have very specific impacts on the life of the bearings in an electric machine. Significant unbalance/vibration can even impact the structure where the machine is placed. Good, not even excellent, practice is to ensure that the balance of a machine is as precise as it can be made in a reasonable length of time with the tolerance being the MAXIMUM unbalance and vibration, not the target.

For more information: in the archives section.

Impact of Stripping Electric Motors and Asset Health

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With the higher temperatures needed to deal with new insulation systems and tight windings (full slots), the part of the repair industry that requires the use of incinerators, commonly referred to burn-out ovens, to remove windings has been striving to allow great and greater stripping temperatures.

Older electric motors had stator cores that consisted of annealed steel that had interlaminar insulation that would begin to break down at 400Fand later not too much greater.  Even then, rewind incinerators would often allow temperatures to climb to 1000F or more.  The result was severe impact to the energy efficiency of the electric motor with greater operating costs and reduced reliability.  This is easily observed as an increase in no load and loaded current as energy needs to feed the damaged stator.

An area that has been carefully avoided then as now, is the mechanical impact on the stator frame.  This can be
directly observed as the need to significantly change shims as the stator frame twists from the heat.

With newer electric motors there is some improvement in the thermal resistance of the stator cores.  The result has been proponents of high temperature stripping, or winding incineration, to find ways to justify higher and higher stripping temperatures.  Although even the latest motor repair trade association ‘study’ calls for keeping temperatures at 650F unless you can guaranty a certain type of stator core, then you can increase the temperature to 750F, the latest marketing data for repair shop incinerators identifies a stripping temperature of 800F.

Published information by the US Department of Energy and the trade association state that through this process you can only successfully strip a stator 2-3 times before having to replace the core or the motor.

There are alternative motor repair practices, such as low temperature stripping, that have been identified as not damaging to the stator core.  Stripping times are faster and these processes are supported by the US Navy (Navy Repair Manual) and Canadian Electrical Association independent studies.

For more information on the impact of motor repair and stator core stripping practices go to the Archives at

MotorDoc Paired with Relentless Family

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I am honored to represent Milena Urquia, a powerful 2-1/2 year old fighter, on the Relentless Stage as part of Team Hope 2015. Milena is fighting Primary Immunodeficiency Disorder which weakens the immune system making her more susceptible to infections and other health conditions. Milena requires life-saving infusions of immunoglobulins every three weeks. I have been in touch with Milena’s parents who have also been strong with support of family, friends and faith regardless of the obstacles before them.

Team 2XL and I look forward to represent Milena through all aspects of the Relentless 2015 program!


Relentless Minnesota raises funds for HopeKids, a national not-for-profit (501c3) that provides ongoing events and activities and is a unique support community for families that have a child with cancer or other life-threatening medical conditions.

Please show your support by donating any amount that you feel is appropriate. If you would rather donate some other way, please message me. Our first event is coming up in a few weeks with the 2015 Relentless kick-off! We hope to be raising our target by the kickoff event comes around.

Additional information on the Relentless program can be found: