On April 13 - Maintenance-Tips published the following Motor Testing Tip:

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“Voltage distribution on motor startup

Of electrical failures in motors, the vast majority of problems begin in the winding insulation, not the groundwall insulation. Everyone owns a meg-ohm meter but may not realize its shortcomings. A meg-ohm meter puts an even voltage across motor windings and will basically tell you if the motor is grounded or not. It is extremely limited as a predictive maintenance tool. You can drive a nail through the copper windings and not detect this with a meg-ohm meter unless it interferes with the groundwall insulation. During startup, a motor experiences voltages 3-5 times operating voltage due to contactor bouncing and other reasons for a vfd application. How many times have you witnessed a motor fail on startup? This voltage decays exponentially as it travels through the motor windings, thus causing a voltage difference between copper windings. The highest voltages are near the lead terminal and the ONLY way to duplicate this phenomenon as far as voltage amplitude and rise-time is the surge test. Surge testers output a fraction of the actual current a motor sees during startup. Find arcing problems early on with the surge test weeks or months before it turns into a shorted turn. Once a shorted turn is present, you will have a failed motor before you finish your lunch.”

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We received a number of emails questioning this tip so we asked our resident independent Motor expert, Dr. Howard Penrose to clarify. We also invited other motor testing vendors to comment, however they declined.

Howard’s comments:

“It starts out ‘ok,’ but becomes somewhat inaccurate. IEEE papers have proven, that repetitive high voltage testing on a new or good winding (clean and dry), has no impact on the condition of the insulation system. It is other operational and environmental issues that have an impact with the failures often occurring well within the winding more than the 2-3 turns that is evaluated with surge testing, in a large number of instances.

The claim that surge is the only way to detect these types of problems flies in the face of the independent findings of the US Coast Guard, GM, US Steel, Boeing, etc.

Yes there is some level of chatter as large motor contacts close (bounce) that causes some voltage spikes. The cause of failure on startup is actually the movement of the coils as the winding surges as shown in the video linked below. There are also quite a few independent technical papers, books, etc. that cover this issue.

Surge testing and MCA have their places and strengths and weaknesses, including the individual vendors within each technology.”

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We apologize for any confusion we might have added to this important topic.

Thanks Howard. Further comments should be directed to the Motor Forum at http://www.maintenanceforums.com

View the Coil Movement Video

Understanding the knowledge and skill level of the workforce is very important. Develop your PM task with appropriate detail so that pertinent information is always at hand. Flexibility in job assignment will increase along with your personnel’s skill and knowledge levels. Workers can then function without higher-level assistance in many tasks. This is a Win-Win-Win situation; the Worker, Planning and Scheduling, and the Company!

Tip provided by Porter H Claytor CPMM
CNS Associates
http://www.cnsassociates.net

More planning and scheduling resources

PdM-2006 Post Conference Workshop
September 15, 2006
Chattanooga TN

Led by Mark Latino

Basic Failure Analysis (BFA) is intended to provide facility personnel the requisite skills and knowledge to eliminate the problems and chronic failures that they are experiencing everyday on the job.

Attendees are provided instruction on a unique 4-step process that guides them through the technique of solving chronic problems down to their root cause(s) using real world examples. In addition, BFA details guidelines for the support mechanisms necessary to implement countermeasures to identified root cause(s).

Because of its modular design, BFA exercises utilize examples of the different types failures that are experienced by various organizations (safety, maintenance, environmental, administrative, process, operational, etc.). This enables BFA to be tailored to meet the specific needs of plants and organizations.

Space is limited and filling up fast so please call toll free (888) 575 1245 or…

Register for a PdM-2006 Workshop online

Quantifying the potential benefits of a reliability initiative, as well as the likely costs to improve performance, in your corporation, is necessary. Here is some guidance.

The Benefits:

• Maintenance Spend Reduction
• Inventory Reductions
• Energy Consumption Reduction
• Increased Uptime
• Improved Quality

The Costs - major investment categories typically include:

• Development of Corporate Standards
• Development of a Roll-out and Implementation Strategy
• Creation or Improvement of Foundational Information (i.e. master equipment list, materials catalog)
• Objective Criticality Ranking of Equipment
• Methodical Analysis of Failure Modes
• PM Optimization
• Creation of a Balanced Metrics Measurement System
• Training and Awareness
• Culture Change
• Compliance Monitoring
• Continuous Improvement

Tip provided by Management Resources Group

View The Business Case for Reliability iPresentation to Learn More

Characteristics of a poorly designed accountability system:

a. Based on fear and aspiration

b. Reward levels generally the same for all

c. Non-performers still get a reward

d. Low performers do not improve

e. Punishment the same for all types and magnitude of
error

f. Does not inspire workers to perform

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

Learn more about the Reliability Center

Human Error Reduction for Supervisors

PdM-2006 Post-Conference Workshop
September 15, 2006
Chattanooga TN

This interactive one-day workshop will pit teams of five against each other in the challenge of maintaining their electric motor systems for the greatest positive impact on business. The assortment of teams will provide the attendees a unique series of options that they can bring back to apply at their companies.

Each team will select motor maintenance philosophies such as reactive, proactive, outsourced or other hybrids and styles. A budget and options will be assigned and technologies purchased for application for fictional sites. Each site and options will end up being unique, including within the same company structure, and also tailored by the players.

The day will start with training in the use of the game, then we will break up into teams and the moderator. Budgets will be assigned to the team administrators for distribution amongst each team, cards related to the specifics of the motor systems for each site, the purchase of technology, personnel and philosophies and outsourced capabilities. The game will be time-limited to the end of the day, 52 moves (52 weeks) or until one winner emerges. Actions and reactions will be based upon probability with decisions and philosophies affecting the outcome. The objective is to have a remaining budget and to stay within production loss limits. If either limit is crossed, the team is out of the game.

Work with your motor management budget and production loss limits. The team with the most toys and money at the end… WINS!

Space is limited and filling up fast so please call toll free (888) 575 1245 or…

Register for a PdM-2006 Workshop online

To reduce and hopefully eliminate downtime from blown pipes in our mill slurry circuits, it was agreed to increase the frequency of thermal imaging of the pipe work to help predict failures as an interim fix (whist a long term fix was being formulated).

New to Condition Monitoring but with 3 years experience in the Concentrator area I took about the task with great enthusiasm. Some of the initial problems were my initial inexperience with the thermo camera and the difference with the internal linings of the pipes (rubber and different ceramics). Other determinations were what kind of temperature differential indicated a problem and where it was on a specific spool were important. My experience with how the slurry (bottom aperture on the screen deck is 12 x 30mm) and the knowledge of the normal high wear points has led to a massive reduction in downtime. I started to check the temperature of the slurry coming out of the mills to help determine the temperature the slurry would impact on the pipe work. This helped immediately to determine the severity of the internal lining degradation.

To quantify my point there is a SWAT team that I was involved with to help prevent the estimated $5,000,000 downtime per year. So far the team has not made any significant recommendations. At this stage due to my efforts there has not been a single pipe blow-out in 3 months. Added to this is where I have found thermal abnormalities in tanks/ pipes in other areas in the Concentrator which have the potential to cause total plant shutdown. Now the maintenance team have a chance to plan internal inspection and repairs to the equipment during planned outages. At this stage I would conservatory put my efforts at $1.25m savings with ongoing continuity. Our thermographic camera is about 7 years old and is in the process of being updated. Let your management know a thermography camera can pay itself off in weeks/months not years.

This Tip was one the tips selected from the PdM-2006 Maintenance-Tips Challenge and was provided by Patrick Walsh, Maintenance Specialist, BHP Billiton, Roxby Downs, SA, Australia

Thanks Patrick - your PdM-2006 Proceedings CD and Maintenance-Tips hat will be shipped as soon the CD is published.

Attend Greg Stockton’s NFPA 70E For Thermographers Mock Trial at PdM-2006

Within a two week span, I was asked to check wildly vibrating control panels on two different production lines that were connected to the main machine. A vibration reading taken on them indicated a single spectral peak; on one machine the peak was at 13.5 Hz, the other 21.35 Hz.
Using a strobe light set to the respective frequencies, I was able to stop the parts supplying the forcing frequency that was exciting the natural frequencies of the two panels.

In one case, the cogged belt pulleys in a change box was the culprit. Since this was scheduled to be changed out, nothing was done. The vibration on the panel went away when it was replaced.

In the other case, the strobe showed several components from a gearbox were indicated. During the weekend, the gearbox froze up and had to be replaced. After being replaced, the panel ceased to vibrate.

I’m sure these faults could have been found mathematically, but it was so much easier to use the Strobe Light instead.

This Tip was one the tips selected from the PdM-2006 Maintenance-Tips Challenge and was provided by
Jon McFadden, Reliability Mechanic, Kimberly-Clark, Conway AR

Thanks Jon - your PdM-2006 Proceedings CD and Maintenance-Tips hat will be shipped as soon the CD is published.

More Vibration Resources and Links