When I referred to sub-100 hp motors not being suitable for PdM I guess I should have specified non-mission critical motors. Most motors that I have come across in the sub-100 hp range are workhorses being used on a stand-alone piece of machinery. If they fail then the machine fails without immediate impact on the rest of the plant.

A typical customer would have 40 pieces of machinery each having a dozen important motors. I say important in that these motors if left to fail would result in the loss of the use of ONE piece of machinery. Quite honestly there might be one or two motors at most at a given facility that would force a complete shutdown in the event of failure. Shop air compressors come to mind. Now to confidently be able to offer a program with a reasonable chance of eliminating MOST motor failures would require the purchase of at the very least an IR camera ( for motors you can see ), Vibration Analyzer ( for motors you can not see ), a Surge Tester ( for motors you want to stress test ) and a low-voltage tester ( for motors that you do not want to stress ). The latter two winding testers depending on what side of the fence you sit will still miss some faults as practical experience has shown. A power quality analyzer is an additional helpful tool.

Now that I have invested something in the order of $75k I can still not really ensure my customer that I will find all his motor faults, but hey I can find most of them. This limits me offering a performance guarantee. Okay so now I have about 500 motors to test on a regular basis. Each motor if it fails can cause a loss of something in the order of about $2000 lost revenue per 8 hour shift. To use these test instruments requires that I shut down production and spend likely 4 hours per motor from start to finish doing these comprehensive tests and generate reports. Assuming I ask $100 per hour to perform this service ( hell I get $85 per hour if I just let the darn thing break and then fix it ) then I earn a bonus $15 per hour towards my $75,000 investment in diagnostic tools. I would require 2000 hours to do the entire survey and would be asking $200,000 to do the job. The customer would also incur at least 1000 of those 2000 hours as pure downtime. I would quickly be shown the door.

This strategy clearly does not work. PdM needs to be at the first stage completely unobtrusive to production. IR scanning, Vibration analysis, and Power Quality analyzers in conjunction with traditional techniques need to be used to identify flags which subsequently get verified with intrusive ( shut down the machine ) methods such as winding testers. This will still acrue downtime but it would be kept to a minimum. Labour performing the testing is still very significant.

Before you say it should never take 4 hours to test a motor I would like to add. To do an IR inspection of an entire machine with guarding all around it requires a lot of preparation before and reassembly afterwards. Motors are often under floorplates or up in the air buried in the machine itself. It is not unheard of to take an entire day to do an IR inspection of a dozen motors on a machine and this does not even include the time spent afterwards reviewing images and preparing a report.

I just do not see where most industries can absorb the cost of a predictive maintenance program utilizing this expensive equipment. I service equipment now and owning and using a dozen standard test instruments ( multimeters, meggers, oscilloscopes, tachometers, etc. ) is just part of my repertoire of tools. PdM test equipment is priced so high that the return on investment is unrealistic for most potential users. Everyone loves the idea of being proactive with their machine maintenance until you tell them that they need to spend $400 on each and every motor on the shop floor. Then you drop the bomb on them and tell them that they should probably do it quarterly for the first year.....

Thanks,

DanS

Just to give another perspective to this. First of all using motor testers as a predictive tool you would not shut a unit down during production to perform testing (unless performing trouble shooting) The off-line testing would be performed during normal shut down periods. Non intrusive on-line testing would be performed with these testers during production and this data trended. Performing these tests takes a few min. per motor and gives critical data not only on the motor but the entire power system. Depending on the layout of the MCC’s 4 to 10 motors can be tested in an hour. As for the cost of an unforeseen failure, the numbers that I typically hear from my customers is much higher than $2,000.00/ 8hr. shift, sometimes several thousand/hr. But then this number can be and is figured several different ways depending on the individual plants outlook.
Will you eliminated failures and down time, absolutely not nor will you with any technology. The strategy clearly does work and has been proven in countless studies. I just don’t see where most industries can afford to not pursue this type of program. The only decision would be whether to purchase for an in house program or bring in a qualified contractor to perform the service.
Just another opinion.

I concur with JOA1. I test around 225 motors every quarter for a company. If I were to add the time it takes me to test these motors it comes to be about 7 to 10 Days depending if you find something and you want to do some investigating and some other testing. The testing I am talking about is On-Line. As JOA1 states the off-line testing is done on a scheduled shut down.

Regards

Thanks guys for the feedback. I am not trying to sound negative about this concept but quite the opposite would love to figure out how to make it work.

JOA1
You mean to tell me that you can identify the location, establish a safe approach, connect to the MCC, record the data, download this data into your PC, organize the data in individual folders, review the results of the data, verify to past results in history, AND generate a report all in a few minutes....

I suppose you were just referring to taking the actual measurement during a shutdown. Cripes with all my years on the floor I would still have to say it takes me a good 20 minutes to do some basic checks on a motor using a megger and multimeter. Would love to learn how to cut that down to a couple of minutes and better yet still be able to bill for the full twenty minutes. The catch is that if you take 4 minutes to analyze a motor then that is what the customer wants to be billed for....

I was implying that factoring the cost to properly analyze a motor would have to involve all the labour and not just the measurement. This is ofcourse obvious. I am not sure what downtime you guys are talking about. Production machines do not have downtime UNLESS a PM or PdM program forces it which then becomes another cost factored into the overall cost of PM programs by the bean counters.

200 - 500 motors per facility would be the norm for my customer base and this would be about 35 customers. After a year and a half doing thermography on these machines, I have yet to figure out how to recover the cost of just the thermal camera. Despite educating the industry of the wonderful technologies out there, these companies will pay me no more to walk into their plants with a thermal camera than they will to have someone come in with a multimeter. They pay me thousands of dollars to walk in and repair their damaged servo drive and accept it as a cost of doing business. They will never pay me $100 to tell them that their electrical panel is dirty and the heatsinks on the drives are plugged. Go figure....

I would love to entertain the idea of trying each of the various PdM technologies but each venture quickly enters the $20k zone and anyone piece of test equipment is really just a complement to the others. You need ALL of them to reasonably identify impending problems on a machine of diverse components.

Jkays
Taking only one week to test 225 motors , analyze the data, and generate a report is exactly what I am looking for. Now do you offer any kind of performance guarantee with that sort of inspection? What kind of training does a fellow need to accurately test and identify that number of motors successfully in such a concise time frame?

Thanks for any advice,

Dan

DanS
If you are truly interested in advice on how you can accomplish all you are asking I'd be happy to discuss it with you one on one. With the equipment I am refering to the data is downloaded while testing and the history is all there in front of you at the time of testing. All is all ready organized in the PC wich is a part of the tester. If I see something out of spec. I flag it and may spend an hour doing the reports after 8 hours of testing. In my area I have yet to find a manufactureing facility that didn't have scheduled down time for general maintenance but maybe your market is different. Again I would be happy to discuss one on one with you, you can contact me at joe.oliver@joainc.net

As JOA1 said my on line test results are put in to the computer at the time of the test and the new data and past data is right there in front of you. You can go to the link below and check out what we offer as company. We are vendor neutral and deal with all the manufactures of motor testing equipment. Feel free to get a hold of us and we can help walk you through the pro's and con's of all the equipment. We all so provide training but I don't think we have any classes set up at this time but when you contact us they should be able to let you know when the next class might be. If you have any questions shoot me an email.
Regards,


http://thesnellgroup.com/Content/MCATraining.aspx