Spare Parts: Take 1
The Power of Feedback
Electrical Troubleshooting Quiz
Spare Parts: Take 2
Practical Implications of OSHA 1926.200
NEC on the Production Floor
Answer to Electrical Troubleshooting Quiz
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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
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Managing motors and generators
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Spare Parts: Take 1
Suppose routine maintenance reveals an impending
problem. You know you need to schedule a shutdown to fix it. Production
tells you the next available slot is seven weeks out. So, you schedule
shutdown for that time, and production schedules shipments around it.
The day comes, and you are still waiting for the replacement parts you
needed. What happened?
Some parts require long lead times -- this is especially true when
you are ordering transformers, breakers, explosion-proof motors, or
stationary batteries. There is no way to shorten the production time
some items, so if the manufacturer tells you nine weeks then be
to wait at least that long.
How can you avoid having to schedule a second shutdown? If your
impending failure isn't too far in the danger zone -- and a shutdown
doesn't require much advance notice -- you could just wait until you
have all the requisite parts. But as you wait, you risk an unplanned
shutdown due to a foreseeable failure.
To balance the risk of missing parts for a planned shutdown against
the risk of an unplanned shutdown, find out from each parts
what the minimum lead time is and then allow a little extra. Consider
- Primary and alternate shutdown dates -- with the actual shutdown
date confirmed based on the progress of the needed parts, which you
need to monitor.
- Pooling the costs of very expensive items (e.g., service
transformers or special motors) within your division or even among
facilities outside your company, so it's affordable to store spares of
long lead time components that are vital to operations.
The Power of Feedback
As part of a preventive maintenance program, Gary uses
handheld thermal scanner to spot bad contactors and connections. He
fills out a form that allows him to simply mark off the items that need
attention. But the form doesn't have space for Gary to note that the
panels need a good cleaning, the lighting doesn't work in one of the
panels, and there's an odd hum coming from a transformer that sits near
So you get shutdown set up, and your team duly replaces the bad
contactors and fixes the bad connections. But they didn't know to bring
a vacuum cleaner (or to provide a way to power it), so they leave the
panel dirty. They don't inspect the transformer either, because doing
so wasn't on the list. When they power the panel back up, flames shoot
out of the vent on that transformer.
The problem and the solution are obvious here. Don't use your
preventive maintenance forms as a means of just getting through
pre-determined activities. Use them as a means of providing information
that will allow you to identify problems as early as possible. Look at
your forms, today -- any room for improvement?
AutomationDirect's new C-more touch
panel is available in 6, 8, 10, 12 or 15-inch versions. Equipped with
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e-mail client, FTP and web servers. www.automationdirect.com/photoelectric
A large, multi-tenant office building is experiencing
excessive rate of replacement for electronic ballasts and lamps on the
third floor. What initial steps you should take to fix this
The answers to this question appear at the end of this
Spare Parts: Take
If equipment goes down unexpectedly, part of your job
to repair that equipment to prevent a recurrence from the same cause.
Another part of your job is to prevent downtime from another cause you
could have prevented during the unrelated repair.
For example, say a motor drive fails. You isolate the cause to the
failure of one IGBT and replace it. But a week later, a second IGBT
fails. This isn't coincidence. Whatever stressed that first IGBT to
failure also stressed the other IGBT to near failure. You could have
prevented the second downtime incident by replacing all of the IGBTs in
that drive at the same time. Ensure your spare parts system allows for
this approach, rather than straight jacketing you into onesies and
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
Practical Implications of OSHA
This part of OSHA addresses six types of signs to use
on a temporary basis: caution, exit, safety instruction, directional,
traffic, and accident prevention. Using the sign appropriate for the
work you are doing and the hazard presented is an easy way to alert
others to potential dangers. Consider modifying your work orders such
that you can include a sign checklist.
Handy tip: Design a checklist with thumbnail examples of each
type of sign.
NEC on the Production Floor
Production areas may have hundreds of branch circuits.
Article 210 is of vital interest to anyone involved in keeping those
areas safe and production equipment running. Taking care of
these circuits involves far more than just being able to replace a 20A
breaker in a panel. Table 210.2 lists more than two-dozen specific
of branch circuits.
Three of the key requirements of Part I of this Article state:
- [210.5] Identify the grounded conductor, equipment grounding
conductor, and ungrounded conductors.
- [210.6] A branch circuit can supply only certain kinds of loads,
depending on its nominal voltage, and certain limitations apply.
- [210.8(B)] Provide GFCI protection in bathrooms, on rooftops, and
outdoors (adding GFCI protection beyond NEC minimums is often
Answer to Electrical Troubleshooting
Look for the causes that are common to that floor but
not to the rest of the building. This rules out low-voltage issues,
except on the load side of the transformer supplying power to the third
floor lighting panels. You also want to rule out power quality issues
arising from heavy harmonic loads on that floor. This is where a power
analyzer can be enormously helpful.
One of the most likely causes is improper bonding -- which results
in ground loops and/or a missing return path for undesired current.
Eliminate any load side bonds between neutral and ground -- check
every possible connection point. Visual inspection can often reveal the
need for missing bonding jumpers, but you should also measure the
resistance between each light fixture and the main bonding jumper to
ensure a thorough job.
Once you've completed this step, walk through the requirements of
Article 250, Part V. Just be careful you don't confuse bonding with
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