December 13, 2005 A PRIMEDIA Property Vol. I No. 4



CONTENTS
Two Ways to Boost Maintenance Effectiveness

Reduce Downtime Through Preparation

Replacing A Transformer
NEC on the Production Floor

New Test & Measurement Web Community


About This Newsletter
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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    Maintenance
    Two Ways to Boost Maintenance Effectiveness

    One. When a piece of equipment goes down for repair, make good use of the downtime. While one team is making the repairs, you can usually have a second group performing the scheduled preventive maintenance simultaneously.

    For example, let's say a motor spins a bearing and must be replaced. That's a good time to conduct insulation resistance tests and inspect the motor controls -- you have to take the motor out of service anyway. Often, you can forego the next scheduled preventive maintenance -- which saves you some money. But the big savings come from detecting and correcting additional downtime causes before a catastrophic failure occurs. Few things are more embarrassing than bringing equipment back online, only to have it fail again days later.

    Two. Many times, preventive maintenance will reveal a "root cause." Unfortunately, there's no red light to tip you off to the real problem so you must watch for other indicators.

    For example, a motor is vibrating due to burned bearings. You replace the bearings. But what caused the bearing damage in the first place? More than likely, it was something that was also damaging other motors in the system. If you perform a failure-mode analysis, you stand a good chance of discovering it.

    In this example, you should schedule several other motors for vibration testing as soon as possible -- preferably within the next 24 hours. For best results, work your way up the power distribution system. Look at other motors on that branch, then at that feeder, then at that panel, and so on.

    If you find the same issue on even a few of these motors, you probably have a systemic issue you can solve now. If you wait to solve it, the cost may include repair after catastrophic failure and extensive downtime -- making your maintenance simply ineffective.

    Remember: It's always cheaper to maintain than to repair. So, while shifting costs to "maintenance" may seem wrong -- it's the correct approach.


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    Repair
    Reduce Downtime Through Preparation
    Does downtime on key equipment make your managers break out in a cold sweat? If so, you must reduce downtime for repair. Contrary to popular practice, the answer does not involve standing over the repair techs and urging them to work faster.

    One answer is to create a response team for that equipment. Drill employees on likely repairs, and simulate the actual repair. If they are well trained in the task, you can see downtime reductions of 50% or more. Compare this effort to the cost per hour of downtime on that equipment.


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    Operation
    Replacing A Transformer
    When a transformer fails, it's easy to read the nameplate data and just buy an identical replacement. But doing so could be costly. When faced with a similar situation, remember:
    1. The transformer failed for a reason.
    2. The transformer was specified for a load that is probably quite different from the load you have today.

    In most cases, the second factor defines the first. That's why it's important to conduct a load analysis before specifying a replacement transformer -- but be sure to account for the type of load -- not just the total VA -- and derate accordingly. But a load mismatch isn't the only potential cause of failure. Also consider environmental factors such as ambient temperature, ventilation adequacy, airborne contaminants, and maintenance practices.

    NEC on the Production Floor
    Walk into a typical industrial or commercial building, and an hour later you can walk back out with a hefty list of Article 110 violations.

    Here are four common violations:

    • Inadequate wire bending and connection space [110.3]. Just because a cable can fit into an enclosure doesn't mean it should. Every cable has a bend radius. Exceed this, and you risk catastrophic failure of the cable.


    • Unused cable or raceway openings [110.12(A)]. Snap-in plugs are inexpensive. Electrocutions are not.


    • Unproven insulation integrity [110.7]. With insulation resistance testers being so inexpensive and easy to use today, every facility should have baseline data on conductors -- plus a program of scheduled testing. You may be totally unaware of insulation integrity problems, until a fireball alerts you that a preventable catastrophic fault (phase-to-phase or phase-to-ground) just occurred.


    • Inadequate working space [110.26]. The NEC and OSHA [1926.403(i)] provide some specific numbers, but these dimensions are minimums. OSHA also requires that you provide enough space "to permit ready and safe operation and maintenance" of the equipment. If your space is less than the 3 feet (for 600V and under), you are in violation. But you may also be in violation if your space exceeds 3 feet -- depending on how well that space accommodates maintenance efforts.

    We'll look at more Article 110 violations in the next issue.


    Manufacturers' Corner
    New Test & Measurement
    Web Community

    Looking for help on how best to use your test tools? Want to know what others think about certain pieces of equipment? If you're looking to learn some new tricks or share ideas and opinions with your peers, check out this new online user community sponsored by Fluke Corp.

    The test and measurement tool users community site (www.fluke.com/community) offers forums on safety and application tips in the areas of power quality and harmonics, troubleshooting, motors and drives, power distribution systems, and predictive maintenance. Registration is required to post new comments/questions or respond to existing posts.


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