March 10, 2006 A Prism Business Media Publication Vol. II No. 5



CONTENTS
Project Activity in the Metals and Minerals Industry Looking Strong

Switchgear Maintenance Includes Testing

Ventilation Fans: Don't Blow It

Electrical Troubleshooting Quiz

Managing Motor Drive Replacement

NEC at the Facility

The Practical Implications of OSHA 1926.302

Answer to Electrical Troubleshooting Quiz



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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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    Project Watch
    Project Activity in the Metals and Minerals Industry Looking Strong
    Current projections in the metals and minerals industry show 587 projects totaling more than $12 billion are scheduled to begin construction this year, according to marketing information resources company Industrial Information Resources (IIR). This is a 17% increase in planned project spending as compared to 2005. Regions showing the greatest growth include the Northeast, Southeast, and West Coast. In fact, spending in the Northeast region is projected to more than double. This is due to several large-scale projects in Pennsylvania. On the other hand, the Midwest and Southwest regions are forecasted to decline during this same time frame.


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    Maintenance
    Switchgear Maintenance Includes Testing
    Too often, switchgear "maintenance" means replacing breakers that have opened and won't reclose or those that have deteriorated in a way that produces nuisance tripping. This is a very expensive way to "save money" on maintenance. This approach also overlooks a key fact: Breakers are meant to break circuits.

    Why is this fact so important? Suppose a mechanism in the breaker freezes, corrodes, or fails in some other way that prevents the breaker from opening the circuit during a fault. You essentially have no circuit protection. But until the fault occurs, you won't know that. When it does occur, some ugly things are going to happen.

    While infrared testing and visual inspections are excellent preventive maintenance tools you should use on a regular schedule, they aren't enough. To properly maintain your switchgear, perform circuit breaker testing. How frequently you should do this depends on the application and the environment. Contact your breaker manufacturer for advice. Be sure to ask about the other components of your switchgear as well.

    Ventilation Fans: Don't Blow It
    Every facility has ventilation, for a variety of reasons -- including OSHA compliance, worker comfort, and equipment protection. As a result, these fans are important. But do you maintain them? Dirt gets into bearings and accumulates on fan blades, causing the fan to turn more eccentrically over time. This means it uses more electricity and makes more noise to move less air.

    You can simplify fan maintenance with instrumentation. When the fan unit is new or recently refurbished, install an ammeter to monitor its supply current. If you use a unit with a setpoint/alarm, you can tie it into your network to alert you when the fan needs attention.

    Fan filters provide another failure concern. Often, these don't get changed because of their location, the mounting method, or some other inconvenience factor -- choking the fan system. Consult your filter media provider about converting critical fan filters to a common media that can use a hook and loop fastening method. Then, hire a sheet metal contractor to rework the duct to permit easy change out of the filter media.


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    Repair
    Electrical Troubleshooting Quiz
    Two identical motors supplied by the same feeder operate identical low-speed slurry mixers, located next to each other. One motor blows its overloads about once a week, and the other motor has no problems. What is the most likely cause of the overload failures?

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

    Managing Motor Drive Replacement
    Over the past decade or so, manufacturers of motor drives have made amazing advancements. Drives are smaller, more efficient, more capable, and more reliable. If you have a drive failure and must order a replacement drive, look at the current offerings and consider upgrading to a newer drive.

    While waiting for your replacement to arrive, take the following steps to protect the motor and new drive:

    • Examine the supply. Look for clean power, proper voltage level, and all phases to be the same voltage.
    • Examine the mechanicals. Look at motor mounting and alignment.
    • Test the grounding (bonding). If your motor is connected to a ground rod driven into the cement and you think that means your motor is properly grounded, read IEEE Standard 142. Then bond the motor per the definition in NEC Article 100.
    • Inspect the load. If the motor connects to a gearbox (for torque magnification), check that box for adequate lubrication. Dry gears happen.



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    Operation
    NEC at the Facility
    Does your facility have a lighted flagpole or sign? How about outside lights, intrusion detection, or other electrical systems outside? Such equipment depends on outside branch circuits and feeders, which means it comes under the watchful eye of Article 225.

    Circuits located outside have more exposure than inside circuits do -- to weather, rodents, and even the public. Thus, they have requirements above and beyond those for indoor branch circuits and feeders.

    For load calculations and ampacity requirements, Article 225 refers you to Article 220. Most Article 225 requirements have to do with routing and protecting the conductors. Pay close attention to the clearances -- what "looks" adequate might not be. In the event of an actionable incident -- such as an electrocution -- the courts consistently render decisions based on Article 225 rather than what "seemed adequate."

    If more than one building or structure is served by the same feeder or branch circuit, spend time in Part II of this Article to learn the requirements. Such an arrangement is common. For example, you may have a single feeder supplying a couple of storage sheds on the west end of your property or a vestibule and a detached guard house may share the same feeder.

    The Practical Implications of OSHA 1926.302
    Power tools are designed to be used in a certain way, both for efficiency and safety. So, follow manufacturers' operating instructions, observe operating restrictions, and use only approved accessories.

    For electric tools, use only insulated or double-grounded tools. If the tool requires AC power, use the proper portable cord for the environment. For example, there are cords specifically for use in the presence of oil or in wet environments. Do not "fix" a cord with vinyl tape if its jacket has been damaged -- replace it.

    Pneumatic tools are commonly subjects of abuse, because "it's just air." But that air is under pressure, and painful injury can result. You may have used compressed air for cleaning, and that's fine. But above 30 PSI, experts consider this dangerous -- which is why OSHA sets a 30 PSI limit for cleaning. It's never safe to use compressed air to clean yourself or others. Doing so can drive materials through your skin and into your blood. A final tip on compressed air safety: Use a positive means to secure pneumatic tools to the hose -- otherwise, the hose might pop off into your face.


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    Quiz Answers
    Answer to Electrical Troubleshooting Quiz
    A low speed slurry mixer is a classic example of a high-torque load. That means these motors have some kind of mechanical drive on the output. Therefore, your problem most likely lies with a gearbox or belt drive. If it's a gearbox, replace the lubricant and ensure the proper level. If it's a belt drive, see if the correct belt is on the correct pulleys at the correct tightness.


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    Copyright 2006, Prism Business Media. All rights reserved. This article is protected by United States copyright and other intellectual property laws and may not be reproduced, rewritten, distributed, re-disseminated, transmitted, displayed, published or broadcast, directly or indirectly, in any medium without the prior written permission of Prism Business Media.