January 10, 2006 A Prism Business Media Publication Vol. II No. 1

Overcoming a Common Maintenance Myth

Electrical Troubleshooting Quiz

Overcoming a Common Repair Myth

Practical Implications of OSHA 1926.151

NEC on the Production Floor

10 Benefits of Adjustable-Speed AC Drives

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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    The designations "National Electrical Code” and “NEC” refer to the National Electrical Code®, which is a registered trademark of the National Fire Protection Association.


    Overcoming a Common Maintenance Myth
    You must follow factory maintenance requirements to the letter.

    The people who wrote the factory maintenance requirements did so with certain assumptions in mind about how the equipment would be used and under what conditions. But your application may be outside those assumptions.

    Does this mean you should disregard factory maintenance requirements? No, and it doesn't mean you should make an "educated guess" on modifying those requirements either. Just as that factory team doesn't know everything about your operations, you don't know everything about their product. You don't, for example, handle the service and support issues that were inputs to those maintenance requirements.

    Contact the factory and discuss your application so an applications engineer can provide you with the proper guidance and reduce your downtime. Getting suggested changes in writing will help you assert a warranty claim, if the need arises.

    AutomationDirect now offers the Cutler-Hammer Enhanced 50 series of high-performance photoelectric sensors, manufactured by Eaton, with prices starting at $44. Thru-beam, polarized reflex, diffuse and clear object models are available, with sensing ranges from 45 inches to 500 feet. All sensors are IP67 rated and are available with a variety of cabling choices. Visit www.automationdirect.com/photoelectric.

    Electrical Troubleshooting Quiz
    Beth is an operator on the plant floor. She complained that her machine sometimes gives her a shock when she touches it. Occasionally, her control panel just blinks out, and she has to reset it to get the display to come back on. What is the most likely cause of this, and how should you check for it?

    The answers to this question appear at the end of this newsletter.

    Overcoming a Common Repair Myth
    If a production machine goes down, you must send someone to work on it immediately.

    This idea is responsible for millions of dollars of lost revenue each year. Yes, you need to get equipment running again. But not all equipment is created equal, and your people are spread thin. You must establish priorities and make choices.

    If Press #8 can produce 100 parts an hour and your factory needs 200 parts per day, Press #8 can be down for a long time. If your facility can sell everything that comes off Line B, then Line B is "critical equipment." Any revenue lost on Line B is lost forever. (Equipment can also be critical for other reasons. For example, it's a production bottleneck or its output is high revenue.)

    Suppose the main drive motor for Line B goes down early in the day. Replacement is a two-person job, and you have three people available at the moment. You send all three, so one can conduct support activities for the other two and handle all those little side tasks that slow a job down.

    Minutes later, you get a call that Press #8 went down. The department supervisor is screaming at you to get Press #8 up as soon as possible, but you've just confirmed the factory won't need any more parts from it for another eight hours -- and those are low-revenue parts anyhow.

    The smart choice here is to keep that Line B repair job moving as fast and efficiently as possible. Ignore Press #8 for at least four hours or until Line B is up. During the wait, you will likely free up someone else to repair Press #8. Do not pull people off of the critical job to handle the non-critical one.

    For Quick
    Motor Change-Outs

    Decontactors are a combination plug & receptacle and disconnect switch. They allow electrical equipment to be safely and easily disconnected and connected - up to 60 hp or 200A. Since there is no access to live parts workers can change out a motor without having to 'suit-up'. Inquire about our free trial program.
    Meltric Corporation, call 800-433-7642, www.Meltric.com

    Practical Implications of OSHA 1926.151
    This addresses fire prevention. The main concept is pretty simple. Keep combustibles and ignition sources separated. The rub is this: Applying this concept is complex. That's why both OSHA and the NEC devote considerable space to requirements for accomplishing this. In general, think in terms of what can burn and what can spark -- and don't let them come together. Some specific tips:
    • When working around flammable gases or liquids, you are working in a "hazardous location" (defined in Article 500). Use only equipment approved for use in that location. You could blow up an entire facility with a penlight, so don't take anything for granted.
    • Don't allow combustible materials to accumulate.
    • Understand the fire characteristics of materials being stored, and provide the proper enclosures and ventilation.
    • Don't stack anything closer than three feet to overhead sprinklers.

    NEC on the Production Floor
    Walk into the typical industrial or commercial facility, and an hour later you can walk back out with a hefty list of Article 110 violations. In our previous issue, we discussed four common violations. Here are four more:
    • Unlocked doors on outdoor transformer enclosures [110.31(D)]. If unqualified persons could gain access to your enclosures, lock those enclosures. (In an actual case, kids from a nearby apartment complex climbed over the perimeter fence). To prevent tragedy and massive liability, study 110.31(D) closely -- and perhaps commit it to memory.
    • Insufficient working space [110.32]. In a misguided attempt to maximize revenue per square foot, people often nitpick code requirements to determine the absolute minimums for working space. They fail to realize that working space is an investment, not a cost. Cramped working space is unsafe, and it inhibits the very maintenance that prevents downtime. It also extends downtime by making repairs difficult and unsafe. This is why the first words of 110.32 are "Sufficient space."
    • Using the 3-foot minimum clearance as the maximum clearance [110.33]. OSHA and the NEC do not, as commonly misunderstood, dictate you must provide exactly 3 feet of clearance (or maybe a little less, if you can hold your ruler at an angle) in front of energized parts. In fact, the minimum may be more than 3 feet (Table 110.34(A) and OSHA 1926.403). Operational and other issues might provide bottom-line reasons to go beyond NEC and OSHA requirements.
    • Failure to properly illuminate working spaces around electrical equipment [110.34(D)]. People can't work safely in the dark. Tip: Try to ensure the illumination doesn't draw its power from the equipment it illuminates. For example, if your facility has two service entrances, power the lighting for each one from a breaker at the other service entrance. When production stops, do you want to wait while your repair team runs extension cords and cranks up portable generators?

    Manufacturers' Corner
    10 Benefits of Adjustable-Speed
    AC Drives

    Since motors consume a large amount of the energy produced in this country, it's only fitting that manufacturers and end-users continue to look for ways to cut down on the amount of energy they consume. Automatically controlling the speed of a motor as it relates to changing loads is much more efficient than running a motor at a constant (fixed) speed. That's where adjustable-speed drives (ASDs) come into play. The folks at ABB have developed a list of 10 benefits users realize when operating their motors with ASDs, including:
    • Controlled starting current
    • Reduced power line disturbances
    • Lower power demand on start
    • Controlled acceleration
    • Adjustable operating speed
    • Adjustable torque limit
    • Controlled stopping
    • Energy savings
    • Reverse operation
    • Elimination of mechanical drive components
    For an expanded discussion on these 10 benefits, visit ABB's Drives Portal on the Web.

    Quiz Answers
    Answer to Electrical Troubleshooting Quiz
    These are classic symptoms of flashover. To test for it, use your digital multimeter (DMM) with peak recording and measure the potential between metallic objects in the area. To fix the problem, install equipotential bonding (Article 250, Part V).

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