Motor Maintenance Tip, Part
Working Your Work Order
Recovering Repair Costs
NEC in the Facility
Answer to Electrical
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Tip, Part 4
If an angry elephant charged into your home, the amount
of damage would be catastrophic. Yet, if you asked homeowners in your
that nobody carries insurance against rampaging elephants.
Are these people crazy? Of course not. Elephants don't rampage
through homes in our country. We forego elephant protection and spend
our prevention and insurance dollars on events that are more likely.
Apply this same philosophy to your motor maintenance program. There
are more than 70 different tests you can do on a motor, most of which
you don't need to perform. However, if you neglect the few tests you
doing, the consequences can be expensive.
Which do you need? Identify the most likely failure causes for
each motor. Determine which tests are appropriate for each cause, and
what resources you need to adequately perform those tests. Finally,
weigh the cost of testing and prevention against the cost of
Work Order System
Does your work order system sometimes get in the way of
maintenance and repairs? One key to preventing this issue is to make
sure you don't use the same process for urgent work as you do for
non-urgent work. Your work order system should schedule
non-urgent work, such as PdM, PM, and project work. But it should
follow a direct method of initiating urgent work, such as a
supervisor's issuing verbal instructions.
When an equipment failure is affecting production, you have a
high-priority situation. In non-urgent work, your work order system
leads the action. But in a high-priority situation, the work
order helps move work that's already in progress. By removing
need to wait for the work order, you remove an unnecessary barrier to
How well do your work orders support those doing the work? Good work
orders include information such as:
For non-urgent work orders, add:
- What. Identify the specific equipment, permits, procedures,
materials, tools, and test equipment needed to do the job. When this
information is in a standard work order (e.g., a PM), you eliminate
duplication of labor and sources of error.
- Where. Provide the location of the equipment and its power
- Who. Note the specific skills and certifications required
this work so it doesn't get assigned to unqualified personnel. Also
which job titles (e.g., control room supervisor) must provide
permissions and sign-offs.
- Why. Explain the purpose. For example, "IR measurements to
identify loose connections."
- When. Show the intended start date.
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Line Four has been blowing circuit boards for several
months. Current and voltage measurements by the DMM look normal. An
electrician accidentally discovered the cause during a Line Four
installation project while adding up the loads. It turned out that the
75kVA transformer was already supporting 91kVA of load.
What piece of test equipment could you have used to eliminate
repeated and fruitless DMM measurements months ago?
The answer to this question appears at the end of this
Your company's executives think of repairs expenditures
as losses, not investments. "We spent $30,000 on repairs." To them, the
money is gone forever.
In reality, the money is recoverable. How can this be? Think of
repair expenditures as tuition. Now that you've spent this money on
repair, what can you learn from it? Places to look for "lessons
- Root cause analysis. Prevent occurrences in this and related
equipment by identifying the cause of the cause (e.g., a bonding error
rather than "a voltage spike").
- Training deficiencies. Determine what mistakes people made,
what false paths they followed, and what rework occurred during the
repair. You have now identified specific training needs.
- Test equipment deficiencies. If troubleshooting took a lot
time or involved critical equipment, closely examine the
steps taken. How much downtime did you "spend" due to lack of a TDR,
power analyzer, thermal camera, digital megohmeter, ultrasonic
or wire tracer?
NEC in the Facility
Excess heat is the number one enemy of motors. We
usually look to electrical causes, focusing on such things as harmonics
and bonding errors. One pervasive cause isn't even electrical. Motors
need adequate ventilation, and the NEC requires you provide it
The NEC doesn't provide specifics to define "adequate."
However, your thermal camera will. If you're getting heat transfer
from the motor to the surrounding air, you'll see a thermal gradient as
evidence of this. The presence of this gradient doesn't necessarily
mean there's enough space around the motor. You also must allow
sufficient room for maintenance [110.26]. Maintenance space may be
greater than the minimum working clearance required by Table
When you operate energized disconnects and circuit
breakers, do you do so in a safe manner? If you enter an equipment room
with no personal protective equipment and stand directly in front of
energized devices when operating them, you need to rethink your work
practices. It's critical to always consider the potential arc flash
blast path and where you are in relation to it.
Electrical Troubleshooting Quiz
When electronics are burning up, even though a DMM
correct voltage and current, a likely cause is waveform distortion.
Using a power analyzer, you can identify waveform distortion in
seconds. In this case, the overloaded transformer would have produced a
flat-topped waveform due to core saturation. This "expensive"
pays for itself in replacement parts alone, not to mention downtime and
reduced exposure to personnel (think NFPA 70E).
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