Another situation you may run into on a production line is
electric motor burn out. This blog tells you how an experienced engineer
would deal with the problem.
When you are dealing with this situation the first thing you do
is start asking a some questions. Is this the first time this motor has
burn't out? Chances are that it is not the first time. What you will
find is that the last time they just found the exact same motor and replaced it.
It could have been replaced last week, 30 days, or 12 months ago.
The next question is "What do you think happened when the motor
failed?". You will get some more information but it may not be accurate if
the machine operator was involved. What probably happened was the machine
was overloaded or it crashed somehow. This is yet another situation where
a Machine Monitor
can be very helpful.
It is also helpful to keep in mind that when someone sells a
piece of machinery it usually has the smallest, cheapest hardware they can get
to make it run. And electrical components are always the first thing to
fail. So a process improvement mindset is what you need for a permanent
fix.
Once you have some background on the problem, the next thing you
must do is look at the motor nameplate specs. The nameplate will have
something like this on it.
**Voltage: 115/230 VAC or 230/460 VAC
**Phase: 1 PH or 3 PH
*HP: 2 HP
**Frame: 145 T
*RPM: 1800 or 3400 (Revolution per Minute)
FLA: 11 A/22 A (This means full load amps).
Hertz: 60 Hz
**Shaft dia: 5/8"
TEFC: (This means Totally Enclosed Fan Cooled)
Drip proof: (Drip proof is marketing lingo for "OPEN and
exposed". It means water can still get into the windings through the side
vents. Never buy drip proof in a wet environment. )
Farm duty or Inverter duty rated. (This means the windings
can take heat and heavy punishment like stop-start or AC drive.)(If the motor
stops more than once every 2 minutes you need a clutch/brake motor or Demag.)
Model No: (Means nothing unless you buy the exact same motor.)
Cat No: (Again means nothing.)
Also the wiring diagram is usually on the name plate. So
write down the information and mark the wires when you take it out.
Whew! That is a lot of information. You can see why
the last time the motor failed they just replaced it with the exact same motor.
How to Upgrade an Electric Motor
If the electric motor has failed you may want to replace it with
a slightly larger motor. Here is my advice on how to select a larger
motor. Take a look at the nameplate data above with the asterisks(**).
These ** items must match the new motor exactly. The * items only need to
be close. This means that Voltage, Phase, Frame, and Shaft diameter should
match exactly.
The RPM and HP only need to be close to the same size. This
means you can upsize the HP slightly within the same frame size. If you up
the HP than you must check on the wire size, overloads, and fuses because the
new motor will draw a little more current. Take the nameplate specs and
look around ebay to get some idea on all the different types of electric motors.
You can also go up in frame size but it means you have to change
the motor mounting and you will need help from a machinist. Be sure to
check that the bigger motor will fit into the same location.
You should also consider putting in a soft-start motor starter or
AC drive. Soft starting improves motor reliability because is reduces in
rush current at start up.
