November 10, 2005 A PRIMEDIA Property Vol. I No. 2



CONTENTS
Three Ways to Reduce Maintenance Costs

Three Ways to be Kind to the Training Budget

PLC Troubleshooting Quiz

The Practical Implications of OSHA 1926.102

Specifying a Replacement Motor

NEC on the Production Floor
Mechanical Execution of Work [110.12]


Old Equipment: Repair or Replace?

Answers to PLC Troubleshooting Quiz


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

     
    Maintenance
    Here's a few more sets of three we thought would be worthwhile to share with you on the topic of maintenance management.

    Three Ways to Reduce Maintenance Costs
    1. Use mass relamping. Changing lamps as they fail multiplies labor costs enormously. Research mass relamping, and consider outsourcing this function.
    2. Test. Scheduling PM work purely by the calendar doesn't account for actual conditions, so it tends to raise costs. Test, so you can follow the "If it aint broke, don't fix it" rule.
    3. Monitor. Power monitors, motor monitors, and similar devices reduce maintenance labor -- they also alert you to take corrective action before an emerging problem causes an unscheduled shutdown.

    Three Ways to be Kind to the Training Budget
    1. Tie training to revenue per equipment. The single largest training cost is avoidable loss of revenue due to critical equipment downtime. While this cost isn't in the training budget, tying training -- even general training -- to specific equipment by revenue will improve the company's bottom line and help justify training expenditures.
    2. Supplement formal training. Subscribing to related newsletters and magazines fills holes in the formal training, and refreshes the lessons learned.
    3. Use "Those who teach, learn." When someone returns from formal training, assign that person the job of giving a short presentation within 30 days. The preparation for this presentation will strongly reinforce the learning you paid for. To make this effective, ban the use of PowerPoint. This isn't about spending time manipulating slides. It's about communicating.



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    Repair
    PLC Troubleshooting Quiz
    Based on some feedback we received following the release of our first issue, we'll now include the answers to the quiz questions in the same issue in which we post the questions.

    For this issue, we decided to post the same questions as last time, but also list the answers to these questions at the end of the newsletter. This will be our presentation format from this point forward. No peeking now!
    1. A system under PLC control suddenly stopped running. What is the first thing you should check?
    2. If a PLC controls four valves for a mixing tank, but only one of those valves fails to open, what (in order) are the first three things you should check?
    3. You have been getting complaints about erratic operation of a newly-installed PLC-controlled system. Valves are cycling, and there are wild oscillations in temperature and pressure sensors. What is the most likely cause of these problems?
    The answers to these questions appear at the end of this newsletter.


    Operation
    The Practical Implications of OSHA 1926.102
    This regulation addresses eye and face protection. Anytime you feel lax about eye protection, just remember that a blind electrician is unlikely to find work. Always wear the proper eye protection. Review the relevant safety procedures prior to starting any task. If you are pressed for time, remember that loss of a few minutes on the job is recoverable, but loss of one or both eyes is permanent.

    A lack of a posted sign doesn't mean you don't need eye protection. Wear eye protection any time you are around rotating equipment or live electrical equipment. Equipment has no way of knowing if you are on break, just passing through, or actually on the clock in your work area. Even off work, this applies (hint: read the manual for your lawnmower).

    Rules of thumb:
    • At a minimum, wear safety glasses any time you are on the job site.
    • Wear goggles where dangerous chemicals are present, regardless of whether there is a known splash hazard or not. Seals do leak and explosions do happen.
    • Wear a face shield where there's the possibility of an arc flash or arc blast. You will not have time to react.
    • When in doubt, overdo protection. Goggles may seem silly if there really isn't a splash hazard after all -- but no harm done. If acid splashes your eyes, it's too late to put the goggles on.

    Specifying a Replacement Motor
    When a motor fails, you may replace it with a new one. If the new motor fails in six months, the typical response is to try some other manufacturer's motor. But the manufacturer is rarely, if ever, the problem.

    To prevent repeated motor replacement, install the right replacement motor the first time. Part of doing that is assessing the reason for failure. For a large motor, have a motor shop do an "autopsy" and provide advice. You may pay a premium for a shop to do this on a moment's notice, but that's cheaper than another downtime incident and subsequent replacement.

    Some things to look for:
    • Wrong insulation rating. Ensure your motor is rated for the ambient temperature where you install it.
    • Motor/drive mismatch. You may need a different drive, different motor, or both.
    • Motor/load mismatch. Maybe the motor is too small, or you are using a Design B where a Design C belongs.

    NEC on the Production Floor
    Mechanical Execution of Work [110.12]

    The NEC requires installing equipment in a neat and workmanlike manner, but it doesn't define that. It's hard to obtain a consensus on particulars that apply to every job, but some general considerations always apply:
    • Everything clearly labeled. This reduces troubleshooting time, and makes retrofits and upgrades much easier. For best results, use a labeling machine -- these are easier to use than many people think.
    • Wires neatly bundled. Nothing screams "incompetent" louder than a bird's nest of wires. Part of effective maintenance is keeping enclosures clean -- which is about impossible with wires going every which way. This situation impedes troubleshooting, also.
    • Proper bends in wires. Every conductor has a bend radius specification. Making sharp bends for aesthetics is unnecessary, damages insulation, and can lead to system failure. Make your bends in smooth curves, respecting the radius limit.
    • Holes made properly. Use the right hole-making tools (e.g., punch and die set), so your holes have smooth and regular shapes. Butchering out a square hole with a drill and file, for example, is unworkmanlike and will leave an ugly hole. It's also inefficient.
    • Consistency. It's just sloppy when every cabinet and junction box is done a different way. Develop and adhere to standards for your facility.

    Manufacturer's Corner
    Old Equipment: Repair or Replace?
    When you're dealing with an unreliable machine that is hindering productivity or driving up your operating costs, this can be a difficult question to answer. However, our friends at the Cat Rental Stores have developed this list of factors to consider when determining whether it's better to make repairs to that older piece of equipment or bring in a new machine to replace it.
    • Resale value. Start your evaluation process by obtaining a quote to trade in the machine.
    • Repair costs. Seek a quote for the repair including labor and replacement parts. The machine's age may affect the cost of labor. Maintenance on older machines can be more involved and require more work due to limited availability of parts.
    • Estimated downtime. Find out how long the repairs will take. Lengthy delays can have a cascading effect on your work schedules and productivity.
    After gathering all this information and running the numbers, you may decide that once repaired this piece of equipment will continue to provide value to your business. On the other hand, you may decide investing in this older machine will yield diminishing returns. In this case, it would be better to put the repair money toward a new, more efficient piece of equipment.

    If you opt for replacement, your next question should be: purchase or rent? For some help in this area, check out these past articles that ran in EC&M.

    Equipment Leasing: Is it Right For You?

    Renting Makes Sense


    Quiz Answers
    Answers to PLC Troubleshooting Quiz
    1. If a system under PLC control suddenly stops running, the first thing you should check is the system power.
    2. If a PLC controls four valves for a mixing tank but only one of those valves fails to open, the first three things you should check are: signal to the valve, operation of the valve, input to the PLC for the control loop of that valve.
    3. If valves are cycling and there are wild oscillations in temperature and pressure sensors in a newly-installed PLC-controlled system, the most likely cause is noise induction due to improper wire routing. To fix this, separate the sensor wiring from the power wiring.


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