March 24, 2006 A Prism Business Media Publication Vol. II No. 6



CONTENTS
Southwest Plant Market Heats Up

Taking Care of Your Transformers

Electrical Troubleshooting Quiz

Circuit Board Replacement

NEC at the Facility

The Practical Implications of OSHA 1926.403, Part 1

Answer to Electrical Troubleshooting Quiz



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This twice-a-month
e-newsletter is brought to you from the publisher of EC&M magazine.

MRO Insider addresses topics such as:

  • Working with management and supervision
  • National Electrical Code® on the production floor
  • Safety procedures and programs
  • Troubleshooting techniques
  • Equipment maintenance and testing tips
  • Managing motors and generators
  • Trends in training and education
  • Managing energy use


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    Project Watch
    Southwest Plant Market Heats Up
    The Southwest market region, consisting of Texas, Louisiana, Oklahoma and Arkansas, ranks as the third largest industrial region in the country, according to marketing information resources company Industrial Information Resources (IIR). Last year, the region saw 53 plants startup operation. This year the region is forecasting as many as 105 unique plant locations where commercial operations are planned to begin. IIR reports that more than half of these new plants are already in the engineering or construction phase.

    The industrial manufacturing industry leads the charge with an estimated 40 plants. Although the food & beverage industry comes in at a distant second with 17 plants, this number is twice as high as the past two years and significantly higher than its average over the past ten years. One growing sector to keep an eye on is the pharmaceutical & biotech industry. The pharmaceutical industry is finding Texas a very attractive area for its business due to its transportation routes, technology base, and skilled labor pool.


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    Maintenance
    Taking Care of Your Transformers
    The typical policy for distribution transformers is "set it and forget it." You set the transformer in place, wire it up, and then forget about it until a lift truck hits it or line 3 loses power. There is a better approach.

    Most of these transformers are dry type, which means you aren't going to be doing transformer oil analysis or other maintenance associated with oil-filled transformers. But there are maintenance tasks you can do. For example:

    • Check the vent temperature. This requires only a few seconds and a temperature gun -- so periodic checks are easy. If your facility has given even the slightest nod to efficient maintenance practices, you have a computerized maintenance management system. Use that system to record and trend data points. If you check transformer vent temperature at roughly the same load conditions (e.g., normal operations and roughly normal ambient temperature), you'll know when the transformer is running unusually hot. This can indicate any of a number of potentially costly problems.
    • Check the waveforms. Excellent instruments that have come on the market in recent years allow you to quickly and easily look at -- and analyze -- voltage and current waveforms. These instruments give you the opportunity to spot a variety of transformer issues -- such as core saturation -- and take corrective action. Otherwise, you may be forced to stay late and perform emergency repairs instead of going to your kid's baseball game.
    • Monitor the power. Take advantage of the abilities of today's power monitoring equipment to keep tabs on the load of each phase of the unit. Consult with your power monitoring equipment vendor or a power monitoring consultant about other points to monitor, based on your infrastructure, priorities, and budget.



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    Repair
    Electrical Troubleshooting Quiz
    The facility has ten production lines, all in the same building. Eight of them never experience problems. Two of the lines, made by different vendors and not adjacent to each other, experience regular failures. Both vendors joke that you are using circuit boards as fuses. What is the most likely cause?

    The answer to this question appears at the end of this newsletter.

    Circuit Board Replacement
    Production equipment troubleshooting guides typically help you troubleshoot down to the board level. You identify the board that contains the failed component(s) and replace it. For critical equipment, you probably have a spare board. For other equipment, you probably pay expedited shipping costs to get a replacement.

    But this process is not complete troubleshooting -- which means the associated repair is also incomplete. The board failure was a symptom, not the problem. To complete the repair, you must identify why that board failed. Sometimes, this seems impractical -- the failures are infrequent and the cause is expensive to track down. Have you considered the downtime costs?

    Some checks to do while the equipment is down for board replacement include:

    • Board socket. Look for corrosion, cracks, excess dust, bent contacts, and carbon tracks.
    • Backplane. Same as board socket inspection.
    • Chassis. Look for loose mechanical and electrical connections.
    Checks you can do while the equipment is running include:
    • Enclosure. Look for a ground rod connection. If it's there, you are looking at the number one cause of board failures. Address this issue after closely reading IEEE-142 and NFPA 70, Article 205, Part V.
    • Incoming voltage. Use a power analyzer (or, at the very least, a DMM with high-low memory) to check for low and high voltage on each phase. Also look for voltage imbalance -- if it's more than 2%, contact the equipment vendor for advice.
    • Waveforms. Use a power analyzer to look for waveform distortion at the input to the equipment. If you find distortion, follow it back along the electrical infrastructure to its origin.



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    Operation
    NEC at the Facility
    One of the topics of Article 225 is disconnects. In a new facility, you generally don't find problems with disconnects for outside branch circuits and feeders. However, that situation changes as a facility ages and modifications accrue.

    Typically, the load increases and there's a need to add another feeder. And another. And another. A relatively inexpensive way to add on is to mount another disconnect on the wall to supply a new switchgear enclosure. If this is standard practice, you quickly reach the six-disconnect limit. This approach also makes it hard to conform to the requirement that these disconnects be grouped (which allows first responders to quickly kill the power).

    How can you avoid violating Article 225 when you need to add capacity? Typically, people come to this "fork in the road" when the existing switchgear is very old and should probably be replaced anyhow. Or when the company needs added capacity because business is booming. Either way, the best solution is to replace and upgrade the switchgear. Consider an extended bus architecture when you upgrade.

    The Practical Implications of OSHA 1926.403, Part 1
    "The employer must ensure that electrical equipment is free from recognized hazards that are likely to cause death or serious physical harm to employees." That sounds fair enough. Just keep those covers on the switchgear, right? Actually, it's a bit more complicated than that. OSHA provides extensive detail on what you must do to meet this general requirement.

    Consider, for example, "Suitability for installation and use." How do you determine if equipment is suitable? OSHA instructs you to look for listing, labeling, or certification for the purpose. It does not mention anything about "field modifications that seem OK." Nor does it allude to the idea that "if it doesn't blow up it must be suitable." OSHA and the courts take a dim view of unauthorized equipment modifications and of applications for which the equipment was not intended. This applies to everything from ladders and cords to transformers and circuit breakers. We'll look at more details in the next issue.


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    Quiz Answers
    Answer to Electrical Troubleshooting Quiz
    The most likely cause is each vendor's installation manual required an "isolated ground," and whoever installed this equipment dutifully complied. This defiance of the laws of physics is the most common reason for board failures in production equipment. Most likely, these two machines are serving as the return path that should instead be provided by the bonding system.

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