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 Post subject: Condition of Maintenance
PostPosted: Mon Mar 03, 2014 7:07 am 
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Open ended question...how do we define the condition of electrical equipment?

This is a tough one. IEEE 493 (Reliability) has a recommended maintenance schedule that changes the PM frequencies based on a combination of two factors: environmental conditions, and equipment condition. The two scales are basically defined in terms of good, average, and poor. Similarly, NFPA 70E at least in the informational notes makes it clear that equipment that is in poor condition should be treated differently from equipment in good condition.

There are great reasons for this because obviously at some point critical safety functions may fail to operate properly with a significant likelihood of failure...e.g., breakers trip slowly or fail to trip resulting in much larger arc flash hazards than predicted, or if there are large holes in the equipment, structural issues, or deterioration to the point where the normally grounded housing becomes ungrounded or worse, energized.

The question then that I have is...how do we reasonably define the standard for this? You can't just say "follow NETA MTS" or "follow NFPA 70B". Those are standards for how to maintain equipment (both preventive e.g. lubrication, and predictive maintenance e.g. IR inspections). But they are somewhat vague in the area of scheduling and both specifically state that maintenance frequencies must be adjusted based on a combination of environmental and equipment conditions. Neither gives a passing score for condition.

Similarly, there are end of life arguments that are similar in nature. For electronic equipment it is usually pretty simple to quantify because manufacturers typically end production/sales after about 5-10 years for that model and have some sort of guarantee of support for typically about 10 years after that point. But for relatively mature technology such as switchgear, there really are no major technological obsolescence issues. Do we go by manufacturer design life...e.g. about 20-30 years for most switchgear, MCC's, etc., or something else? Shouldn't we have a standard for rating equipment for when it is appropriate to repair, when it is appropriate to refurbish, and when it is appropriate to replace?

A huge issue here is that even if we establish a standard what we want to avoid is the situation where the equipment is just so far gone that it is getting repaired during every maintenance inspection and is effectively no longer functional no matter what. This is the point where complete replacement should be triggered rather than just continuing to replace the wear parts.

I know there is a lot of "I know it when I see it" stuff out there but somehow we've got to do better than that.

Reason that this is important is that the 2015 draft of 70E is going to make condition of the equipment a criteria for PPE. So we need to define equipment condition as well.


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PostPosted: Mon Mar 03, 2014 8:00 am 
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Paul, I agree with the "condition of the equipment evaluation" but as you are stating here - sort of - who is qualified to make judgments to the condition of the equipment?
Unless there is a "standard" to define the condition it is subject to my interpretation or in some cases how I feel that day. If I am in a good mood and I like you, maybe your equipment is just a bit better.

This change does excite me a bit but also scares me. I do not know what the verbiage will ultimately contain other than
110.1(B) The electrical safety program shall include elements that consider condition of maintenance of electrical equipment and systems.


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PostPosted: Mon Mar 03, 2014 10:04 am 
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I think I was exploring if there's actually a standard out there. For instance for polymer insulators, EPRI has an excellent "picture book" that has dozens of photos showing examples of good and bad insulators (mostly bad) along with a ranking scheme indicating what damage would be considered essentially cosmetic and what damage indicates that immediate repairs are required. There is enough detail that I can honestly say that it's not a judgement call. It is available for download here:
http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000000001013283

I think if we had an effective scoring system then we could definitely compare apples to oranges. Where this gets tricky though is that this provides a means of ranking equipment condition. The trick would be to go from that to making predicitons...based on current condition of the equipment and environmental conditions, the equipment is likely to fail within a specific period of time. This is the essence of predictive maintenance...performing some sort of test/inspection to determine an estimated time to failure, and making corrective changes along the way to extend this time out.

However we've all dealt with the same old problem. "I can tell you that if you keep running it, it will fail. I just can't tell if it is next week or next year."

To be useful from a safety point of view though, remember that we are dealing with some very small numbers...effectively, outliers. I have been recently looking at a large amount of raw data from OSHA inspections. The number of cases where equipment condition or design played a significant role in a resulting arc flash is much smaller compared to cases of human error being the predominant cause. I think we're dealing with order-of-magnitude issues here. It may be enough that a maintenance program exists and includes certain elements, regardless of ranking those elements.


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PostPosted: Thu Mar 06, 2014 8:26 am 
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Just an observation here but the responses for the question of the week this week seem to indicate that the majority of people think their condition of maintenance is "average". Compared to what? This is going to be interesting. It seems like there is opportunity for a psychological slant where people have a skewed opinion of their own system.

I wonder if people are asked about systems other than their own, how would they respond. I'm thinking along the lines of Congress (bad analogy but here it is). You always hear people hate congress but when asked about their own congress person, they are ok with them. Could this type of slant happen here? Paul's discussion is excellent. There should be some standardized grading method for systems much like the restaurant industry for inspections. Wow, I could see that opening up a huge Pandora's box.


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PostPosted: Fri Mar 07, 2014 9:38 am 
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Great discussion! When I posted this week's [url='http://arcflashforum.brainfiller.com/threads/condition-of-maintenance-2015-nfpa-70e.3223/#post-14959']"Question of the Week"[/url] regarding condition of maintenance, these were exactly some of the things running through my mind. The 2015 Edition of NFPA 70E is placing a big emphasis on "Risk" and moving towards a Risk Assessment rather than strictly the hazard only which is what IEEE 1584 focuses on. This is similar to what I've been working with in Europe for many years - they have been referring to the studies in terms or risk assessment. PaulEngr also wrote a good piece on the forum [url='http://arcflashforum.brainfiller.com/threads/updated-arc-flash-risk-assessment.2998/#post-14551'][Paul's Risk Assessment article][/url]

It will be good to see the process open up to some judgement calls about the risk of a particular task, but it is going to be interesting to see how these decisions are made. This is really going to place an emphasis on someone's interpretation of what is well maintained equipment and make it quite subjective.

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PostPosted: Sat Mar 08, 2014 4:33 am 
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For drawout equipment of older vintages at least, EPRI has a lot of performance/failure data.


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PostPosted: Sat Mar 08, 2014 9:43 am 
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In addition to all the great comments in this thread, here is a bit more information regarding how maintenance will play a larger role in defining PPE according to the proposed 2015 Edition of NFPA 70E.

The 2015 draft NFPA 70E has a new table regarding PPE. It is part of what is replacing the Hazard/Risk Table and is used to determine if PPE is necessary. There are only 3 columns in the table. The first column lists the Task, the second column lists Equipment Condition and the third column is a simple Yes/No as to whether Arc Flash PPE is Required.

Here is an example from the table:
  • Task: Normal operation of a circuit breaker switch or contactor or starter
  • Equipment Condition: 1) The equipment is properly installed 2) The equipment is properly maintained 3) The equipment doors are closed and secured
  • Arc Flash PPE Required: No
There are footnotes that offer explanations of terms used in the column "equipment condition"
  • Properly Installed - Equipment is installed in accordance with applicable industry codes and standards and the manufacturer's recommendations.
  • Properly Maintained - Equipment has been maintained in accordance with the manufacturer's recommendations and applicable industry codes and standards.
This approach makes some sense to me, especially in light of the "interaction" confusion that began with the 2009 edition. However, I wonder how many companies will state their equipment has been properly maintained according to this text?

Many companies have very good maintenance programs and can make the claim but many companies do not. Thinking along the lines of liability/legal interpretations, it will be interesting to see how this will all play out.

Comments??

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PostPosted: Mon Mar 10, 2014 5:39 am 
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I agree some sort of scoring would be helpful in determining what is average, perhaps even a grading system like those used in the resturant industry that depict a health score.

So many points off for wireway covers removed, so many points off for wires falling out of the wireway, so many points off for no current system prints available at the enclosure, so many points off for no up to date PM record, and so on.


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PostPosted: Mon Mar 10, 2014 7:53 am 
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I believe the majority of facilities will overestimate the condition of thier equipment, most do not even know what "properly maintained" really means. The operation and maintenence manual for most breakers will offer specific requirements (Based on time and/or operations) that a breaker should be inspected, lubricated, adjustments checked, etc... they will also list how often they should be "overhauled", very few facilities ever do that.

There are a few new tools available for doing these types of condition assesments. The circuit breaker analyzer http://www.circuitbreakeranalyzer.com/ is a tool for mechanical assesment of breakers, also valuable for first trip data to validate arc flash study assumptions. First trip data is an excellent way to asses true mechanical condition of a breaker in service.

MAC testing http://vacuuminterruptertesting.com/downloads/MAC-vacuum-interrupter-testing-presentation.pdf allows for measurement of the pressure, and remaining life of VI's used in VCB's and vacuum contactors. Another excellent tool for predicting failures and condition assesment.


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PostPosted: Fri Mar 14, 2014 5:03 am 
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A mouthguard is a protective device for the mouth that covers the teeth and gums to prevent and reduce injury to the teeth, arches, lips and gums. A mouthguard is most often used to prevent injury in contact sports, as a treatment for bruxism or TMD, or as part of certain dental procedures, such as tooth bleaching. Depending on application, it may also be called a mouth protector, mouth piece, gumshield, gumguard, nightguard, occlusal splint, bite splint, or bite plane.


For more please click on mouth guard


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