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CONTENTS
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Reporting Tips
Motor Maintenance Tip, Part
7
Electrical Troubleshooting
Quiz
Complex Repairs
NEC in the Facility
Safety
Answer to Electrical
Troubleshooting Quiz
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About This Newsletter
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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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Maintenance
Reporting Tips
Maintenance reports can produce many benefits, but
there's often a huge gulf between "can" and "does." A report that
doesn't focus on business purposes is rarely effective outside of the
maintenance department. For example, production managers don't care
that
you have reduced the third harmonic by 90% on feeders X, Y, and Z, but
they do care when they see the effect stated in terms of increased
uptime or reduced scrap on lines A, B, and C.
Show the value of the maintenance department by reporting on the
following, preferably for each production line:
- Hours of uptime gained.
- Units of output gained.
- Revenue gained.
- Scrap reduced (in units and percentages).
- WIP reduced. WIP is often a buffer that masks other
problems.
Review this list with key stakeholders and ask them if there's
something
else they might find helpful. Don't promise you can provide it --
just
ask who needs what. In our next issue, we'll look at ways to obtain the
data so you can provide that information.
Motor Maintenance
Tip, Part 7
Short-duration high voltages can puncture motor
insulation. At one time, lightning was the No. 1 cause of such spikes.
Now, that distinction has (arguably) gone to solid-state switching
devices
(e.g., computer power supplies or motor drives). This means your motors
are exposed to significant threats from inside your building.
Protect against voltage spikes with:
- Bonding. Ensure that all metallic objects are properly
bonded
(Article 250, Part V) so they are at the same potential. This prevents
high-voltage flashovers.
- Surge protection. Don't rely on just MOVs across the motor
drive inputs. Develop a coordinated system. Start with your service
entrance and work your way toward the individual loads, applying
protection as needed to keep voltage spikes within tolerable limits at
each point.
- Preventive wiring. Route motor supply conductors away from
conductors of other circuits. Where this is possible or practical, you
prevent induced spikes.
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Repair
Electrical
Troubleshooting Quiz
During a scheduled shutdown for circuit breaker
maintenance, you do some minor repairs on a breaker and now need to
lubricate it. You don't have any information on what the lubrication
points are or what lubricant to use. You have an hour left in this
shutdown, and there's not another one scheduled for 6 months. Your boss
says it's obvious what the lubrication points are -- those are the
points that already have lubricant. Your boss also recommends a
specific
lubricant based on the fact it's on hand and suitable for the
application. What should you do?
The answer to this question appears at the end of this
newsletter.
Complex Repairs
Some equipment is complex to repair. If you have had
much experience with circuit breakers, you know they are prime examples
of complex repair work. The crew doing the repair (outsourced or not)
is
involved in an information-intensive task. Each model of breaker is
different, and one mistake can be disastrous.
For that reason, it's inadvisable to proceed with the work until
certain information is available and on hand. When a critical breaker
fails, you don't have time to go off hunting for the information needed
to repair or replace it.
Take the time now to assemble information packages for all of your
critical breakers. Include the following for each specific model:
- Technical bulletins and service bulletins. Create a
quarterly
"PM" to look on the manufacturer's Website for new releases relevant to
your critical breakers. Review these bulletins specifically for
obsolescence and replacement information.
- Procedures for rackout and lockout. Keep these procedures in
your CMMS or other repository, after you do a "dry run" of each one to
ensure it's correct. Note what PPE is required.
- Maintenance manual. If you can't obtain this as a PDF from
the manufacturer, scan a paper version into your information system.
This way, nobody has to figure out who last misplaced that paper manual
or where it disappeared to (apparently under its own power!).
The maintenance manual might not be complete. Assess and fill any
holes.
You need to know:
- Recommended tests and procedures. Consider having a
qualified
electrical testing firm develop a test plan for you, based on its
extensive experience.
- Expected values (e.g., contact resistance). To know if
something's wrong, you must compare your test data to expected values.
- Adjustment procedures. How do you correct a delta between
measured and expected test values?
- Lubrication points and lubricant specifications. A mistake
here can prove catastrophic.
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Operation
NEC in the Facility
A good surge protection plan consists of multiple
stages
of protection. The first stages are lightning protection (NFPA 780) and
then surge arrestors (Article 280), typically applied outdoors. Inside
the facility, install surge protective devices (SPDs) per Article 285.
A
good SPD strategy involves applying sequential stages at successively
lower levels of voltage clamping, an issue not addressed in Article
285.
Safety
The updated NFPA 70E has received some excellent
coverage in the trade press. Unfortunately, many people are still not
hearing the message. They are focusing on minimal legalistic compliance
and looking for loopholes. NFPA 70E isn't about how to slow down your
work. It's about how to keep you safe while you're doing it. Don't look
for ways to defeat the new rules. Instead, look for ways to protect
yourself from the dangers those rules address.
Quiz Answer
Answer to
Electrical Troubleshooting Quiz
If you can't identify the lubrication points, you risk
missing one that's critical or putting lubricant where it doesn't
belong. Mixing incompatible lubricants can produce an abrasive compound
that will destroy, rather than lubricate. Thoroughly cleaning the
breaker first may prevent incompatibility complications this time, but
what about the next time?
If you can't find lubrication information quickly, you could extend
the shutdown until you get the necessary information. Or, you could do
the best you can with what you have, first getting an agreement from
production to shut down again two days hence so you can redo the
cleaning and lubrication. If you have any doubts, don't risk improper
breaker operation (which could result in the loss of the facility).
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