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CONTENTS
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Maintaining for Energy
Savings, Part 6
Electrical Troubleshooting
Quiz
Bottleneck Motor Repairs, Part
2
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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The designations "National Electrical Code" and "NEC" refer to the
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Maintenance
Maintaining
for
Energy Savings, Part 6
Installing energy-efficient motors just makes sense. In
many applications, it even makes sense to replace a “perfectly
good”
standard motor with an energy-efficient one. Unfortunately, the savings
you enjoy during the first few months of operation may disappear early
in the life of the motor. Why does this happen, and what can you do
about it?
A motor is energy-efficient because of how it’s constructed. When
you no longer see the energy savings that justified purchasing that
motor, it isn’t because the motor somehow lost its energy-efficient
features. In fact, the cause of such a loss typically has nothing to do
with the motor itself.
How can you protect your energy savings? Start by ensuring your
motor
maintenance program addresses these issues:
- Lubrication. Common errors include undergreasing,
overgreasing, and using incompatible greases. Prevent the first two
errors by using the upper and lower motor lubrication ports as intended
by the manufacturer. Prevent grease incompatibly by identifying the
correct grease for each motor and not deviating from that. Tip: It’s
the grease base that matters, not the color.
- Alignment. One of the several effects of misalignment is
heavy side-loading, which stresses motor bearings. With enough stress,
the bearings become distorted (or lose material), causing vibration.
Vibration is movement, so you’re paying for electricity to move the
shaft in ways that don’t contribute to the desired rotation.
- Mounting. Your PMs should call for inspection of the base
and
pedestal. A crack in the pedestal can result in vibration. A distortion
in the base can produce misalignment. Many problems arising from
mounting deficiencies are invisible except during a particular point in
motor operation (e.g., during startup).
We tend to think of motors as electrical devices, but notice that the
three issues mentioned above aren’t electrical. Even so, addressing
them in your maintenance program can profoundly affect how much
electricity you save — or not.
Other areas of motor maintenance also affect how energy-efficient
your motor systems are. We’ll examine those in our next issue.
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Repair
Electrical
Troubleshooting Quiz
Your company recently replaced 63 standard motors with
energy-efficient ones as part of its green program. Since the
replacement, however, you’ve been plagued with a sharp increase in
overload trips and motor failures. Production people want you to
reinstall the old motors. Is the problem really those motors, or could
it be something else? How can you find out?
The answer to this question appears at the end of this
newsletter.
Bottleneck Motor
Repairs, Part 2
You can dramatically reduce production output loss by
focusing on motors from a bottleneck perspective. One step in doing
that
is to chart out production flow. Look for any kind of bottleneck, such
as a downstream conveyor that handles the output of multiple upstream
production lines.
You’ll also need to identify which motors support bottleneck
production equipment. For example, if you have pneumatic equipment at
bottleneck points, then your plant air-system motors are also
bottleneck
equipment. Process water and process chillers are two other examples.
Calculate how much bottleneck downtime each motor contributes. You
can correctly set priorities when you use these calculations to
allocate
your resources for reducing repairs. We’ll talk about what those
resources are in our next issue.
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Operation
NEC in the
Facility
Lighting in a Class I, Division 1 location (flammable
gases, vapors, or liquids) must meet special requirements. For example,
you can’t use multiwire branch circuits in a Class I, Division 1
location unless the disconnect for the circuit opens all ungrounded
conductors simultaneously [501.40].
Before you install a luminaire in such a location, ensure it’s
identified as a complete assembly for Class I, Division 1 locations
[501.130(A)(1)].
What about Class 1, Division 2 locations? A luminaire installed in
such a location must meet some very stringent conditions, or it must
conform to the requirements for a Class I, Division 1 location
[501.130(B)(1)]. The conditions are almost impossible for the typical
person in the field to meet with any certainty, so generally you’re
better off installing the luminaire per the requirements for Class I,
Division 1.
Safety
Does your employee safety handbook contain a list of
“don’t do” rules that grows with every revision? If so, your
organization has a dysfunctional safety culture. No handbook can cover
every possible unsafe act. Playing a game of “what might people do
wrong” almost always produces losers. Instead, challenge everyone to
ask, “What must I do to be safe?”
Everyone needs to understand that an act isn’t safe just because
there’s no written (or verbal) rule against it.
Many people take safety shortcuts in an effort to be more efficient.
But analysis of job data over many decades has shown conclusively that
overall efficiency and safety move up or down together. If you optimize
safety, you optimize overall efficiency. Avoid falling into the trap of
seeing what you can get away with.
Quiz Answer
Answer to
Electrical Troubleshooting Quiz
Your new motors have higher inrush current than the
standard motors they replaced, thus the new problem of tripped
overloads. The solution may be a different overload or an adjustment to
the motor drive (e.g., softer start).
The motor failure issue indicates another kind of problem. An
important clue is the sheer number of replacements in this single
project. That was a big job, possibly involving “not quite
qualified” personnel. Therefore, suspect incorrect installation
techniques and related deficiencies.
One of the most common problems in “high failure” motor
installations is the motors are grounded (connected to earth), rather
than bonded (connected to metal). Check each motor system for
compliance
with Art. 250, Part V.
As motors trip or fail, take alignment data and look for mounting
errors before removing or adjusting anything. Send each failed
motor to a motor repair shop for an autopsy. A failure mode pattern
will
emerge. Bearing damage will point you in one direction, winding damage
in another. To go beyond being merely pointed in the right direction,
ask the motor manufacturer’s tech support to analyze the findings and
make recommendations.
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