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November 12, 2007 A Penton Media Publication Vol. III No. 21

Preventive Maintenance

Circuit Breaker Maintenance Tip

Electrical Troubleshooting Quiz

Common Repair Mistakes, Part 2

NEC in the Facility


Answer to Electrical Troubleshooting Quiz


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MRO Insider addresses topics such as:

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  • Troubleshooting techniques
  • Equipment maintenance and testing tips
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  • Trends in training and education
  • Managing energy use

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    Preventive Maintenance
    Review your PM system to see if it conforms to the overall purpose of the maintenance department -- the typical PM system does not.

    What is your overall purpose? You may be surprised to learn that it's not to prevent downtime. The goal of any maintenance department is to protect the revenue stream. Implicit in this, of course, are the requirements of protecting the facility and the people in it.

    Each piece of equipment makes a different level of contribution to the revenue stream. Thus, each deserves a different level of maintenance attention. Focus on completely maintaining the most critical systems and equipment. Systems are "most critical" in this order:

    1. Those that protect people, the environment, or the facility (e.g., fire protection systems). Allow no compromises.
    2. Common systems on which the facility depends for operation (e.g., service entrance and main feeders).
    3. Those that produce the highest revenue or handle critical accounts. The production managers know exactly which are which, here. Get this information from them.
    For systems and equipment of lesser importance, production managers will have to decide what rate of failure is acceptable and what maintenance resources they will pay for to get there.

    Don't put yourself in the position of saying you "tried" to keep everything running when something critical fails. It's better to lose $3,000 on an auxiliary production line than to lose a $20 million customer because chronic power quality problems once again caused a late shipment.

    Don't let individual department managers sway you, no matter how loudly they complain. Have your plan reviewed and approved by the plant manager and by the production managers as a group. Let them work out who must take a hit and who can't take one.

    Circuit Breaker Maintenance Tip
    Experts advise following the manufacturer's maintenance recommendations. However, those same experts (and manufacturers) are quick to point out that those recommendations assume certain things.

    Although many customers see these recommendations as "targets" that are costly to meet, the reality is the opposite. Operating conditions or other factors render the manufacturer's recommendations less than adequate in many applications. This is why breaker manufacturers advise customers to make adjustments for environments with high levels of heat, humidity, or dirt.

    The manufacturer's recommendations are a starting point. Avoid the "check-off-the-box" mentality. Instead, determine what's needed to ensure your breakers work when you need them to. It's not about what you can get away with -- it's about what loss of property, life, or operations you can prevent.

    FLIR's New ThermaCAM® T400 Infrared Camera Features Image Fusion
    FLIR's new, innovative T400 boasts fusion, which allows for easier identification and interpretation of infrared images. Fusion enhances the value of an infrared image by allowing you to overlay it directly over the corresponding visible image. The T400 does this in real-time and the overlay function can be adjusted suit electrical surveys and mechanical inspections. Visit, or call 1-800-464-6372.

    Electrical Troubleshooting Quiz
    A motor drive fails, and you look up its repair history. You notice it's failed several times over the past two years. On the bright side, the repairs take half as long as they did a year ago. What's wrong with this picture? What should you do?

    The answers to these questions appear at the end of this newsletter.

    Common Repair Mistakes, Part 2
    Maintenance techs that perform certain repairs often know exactly what to do the next time a line goes down. But being efficient at restoring equipment to operation is not the same as being effective.

    The culture in many facilities rewards ineffectiveness. Here's the general pattern:

    1. Equipment breaks, production stops.
    2. A maintenance tech rides in on a white horse, six-shooter in hand.
    3. Shortly thereafter, production lines are up again.
    4. The tech rides off into the sunset, while admiring production supervisors look on.
    Though costly, this pattern is typical. People are rewarded for solving problems, because problems bring stress.

    Preventing problems prevents the stress that comes with them, so the emotional rewards aren't evident. From a larger financial and competitive viewpoint, it's far better to prevent problems than to fix them. Nevertheless, that's not the viewpoint many people operate under in nitty-gritty daily life.

    Compounding this paradox is the fact that repair techs are under pressure to get things running again, and every minute counts. The one who satisfies the immediate need looks better than the one who does a thorough job. This affects raises, promotions, training slots, and perquisites. The "slower" tech loses, even when preventing the problem from ever happening again.

    How can you correct this quandary? If you're a maintenance tech rather than a manager, you may feel powerless. But you aren't. What you must do is document the dollar value of correcting the root cause. Talk with a maintenance supervisor to get the revenue per hour on that machine. Then, incorporate that dollar figure into your repair report or trouble ticket. To ensure your supervisor understands the value of your contribution, ask what the annualized value is of that repair.

    If you're a maintenance manager, don't wait for repair techs to take the step just outlined. Insist on it for every repair. This also helps you clearly see where maintenance dollars are being spent effectively versus ineffectively.

    NEC in the Facility
    When you size the overcurrent protection devices (OCPDs) for motor circuits, a kind of reverse logic applies — and it's easy to get confused. Article 430 provides a tool that, if used correctly, will prevent that. Perform your motor calculations in the order shown in Figure 430.1, rather than in the order in which the requirements appear in Article 430.

    Industrial-grade DMMs come with many safety features. However, no design can protect you from unsafe use. Unfortunately, those who misuse DMMS usually don't know they are doing so. Don't assume you know test equipment safety rules just because nothing has happened to you yet.

    Quiz Answer
    Answer to Electrical Troubleshooting Quiz There are several things wrong with this picture. First of all, today's drives are very reliable. When they do fail, it's usually for a reason that has nothing to do with the drive itself. So, repairing or even replacing the drive is usually an ineffective solution Your first step should be to assess the drive environment:

    • Put a power analyzer on the incoming power.
    • Inspect the system for proper bonding. See Article 250, Part V and IEEE Standard 142 (The "Green Book").
    • Conduct insulation resistance tests on all cabling in the motor system and on motor windings.
    • Check the load.
    If you find and correct problems in the drive environment, you're still not home free. Go through the manufacturer's recommended troubleshooting steps, which can be found in the product manual.

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