Two Ways to Boost Maintenance
Reduce Downtime Through
Replacing A Transformer
NEC on the Production Floor
New Test & Measurement Web
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MRO Insider addresses topics such
Working with management and supervision
National Electrical Code® on the production floor
Safety procedures and programs
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.
Two Ways to Boost
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
controls -- you have to take the motor out of service anyway. Often,
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
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
Look at other motors on that branch, then at that feeder, then at that
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
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
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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
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.
For Quick Motor
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
When a transformer fails, it's easy to read the
nameplate data and just buy an identical replacement. But doing so
be costly. When faced with a similar situation, remember:
- The transformer failed for a reason.
- 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
Walk into a typical industrial or commercial building,
and an hour later you can walk back out with a hefty list of Article
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
-- depending on how well that space accommodates maintenance
We'll look at more Article 110 violations in the next issue.
New Test &
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
your peers, check out this new online user community sponsored by Fluke
The test and measurement tool users community site (www.fluke.com/community)
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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