Tipsblog

Motor Testing Tip

I have been testing motors for the refinery that I work for for the last five years. When testing motors using the following tests: Resistance, Megger, PI, Hipot and Surge. If it is a pass or fail test from the tester. Make sure to go back and check the results and compare them to the other motors tested at the same time. Leakage current in (microamps > 10 ) on the hipot test shows signs of moisture or dirt in the motor windings and should be investigated. In 90% of the cases, it is moisture in the motor windings area. The other item to look especially if the motor testing is completed from the motor control center and not at the motor is that the problem might be with the joints or the cable in the motor connection box not necessarily the motor.

Out of 250 motors that I tested, I had 10 motors that failed the testing. Out of these 10 motors only two were actually bad motor windings, four were bad motor joints at the motor and four were bad cables that could have resulted in motor failures in the future. This is especially true if it is the first time that you are testing are a 3 to 5 year run without checking the motor winding integrity from the motor control center.

This reader tip was provided during the PdM-2006 Tip Challenge by Mike Schoenmakers, Operations Electrical Specialist, Suncor Energy Products Inc., Sarnia , ON, Canada

Thanks Mike - your PdM-2006 CD and your Maintenance-Tips hat is on the way!

More Motor Testing Resources and Links

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Human Behavior Tip

Many believe that tightening or adding procedures is the cure-all to ward off human error. In reality, this may have the opposite effect we desire. Tightening or adding procedures does not guarantee compliance. It might protect the organization from certain legal exposures because they can claim they were in place, but it does not guarantee compliance just because they are in place. Making procedures more rigid and plentiful may actually widen the gap between procedures and practice. Procedures rarely can accommodate all circumstances so a certain degree of judgment will be required on the part of the person applying the situation. When you hear on the news tactics used on corporations called “work slow downs” for negotiating purposes, this is where personnel follow the letter of the procedure. They do nothing more and nothing less. In the end less work gets done!

Tip provided by Reliability Center Inc.
http://www.reliability.com

Human Error Reduction for Supervisors

Maintenance Tip

Practical Approach to Maintenance Review

For older equipment, planned maintenance often starts with manufacturer’s recommendations, and then gets added to over the years – often in reaction to some breakdown or incident. Going back, it was very rare for manufacturer’s to really have a handle on the linkage between root causes and preventive maintenance – and the maintenance manuals had a lot of custom and practice routine tasks. It is unlikely that the manufacturer anticipated in his recommendations exactly the duty your equipment would see – or understand the implications to your business of a breakdown. Full RCM is a major commitment, and may not be a realistic economic proposition for lower value decisions, and the ‘safe option’ used to be to keep doing what you always did. Often the technician who carries out the work regularly is not part of the process for setting and reviewing maintenance policy – but these are the people most likely to really know what is going wrong and how effective and relevant the preventive maintenance is. You may also find out a lot about how your delivery process and documentation could be improved:

• Critically evaluate the tasks currently carried out – are they effective and related to modes of failure. Don’t be frightened to remove ineffective tasks – they are probably reducing your reliability and are certainly adding a burden.

• Involve the technicians in reviewing maintenance tasks – it will normally be more fruitful than relying just on paper or electronic data.

• Match the frequency of the maintenance to the duty and consequences of failures – than means thinking about the cost of lost production, and maybe doing things differently on similar equipment.

I am not suggesting this is a comprehensive approach – but in my experience a practical and useful activity. There are modeling tools and techniques out there can optimise these activities – particularly getting the intervals right and I would certainly endorse a practically founded RCM based strategy based on data and knowledge.

Tip provided by Peter Jay of The Woodhouse Partnership Ltd.
http://www.twpl.com

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