On 4/30/2015 10:32 AM, Leon Fisk wrote:
I'm guessing that this is the model you're working on:

http://www.festoolusa.com/power-tool...tractor-583492

Yes

... Maybe the temperature sensing mechanism
is at fault and not the motor.

I don't think so, because of the large currents that I am measuring.

....
Any loose heat-sink items on the electronics board or something that
could mess up the temperature sensing?

The temperature sensor is on the side of the motor. There could be
circuitry that reads it on the board, but I do believe that it does
overheat, from the currents I measure.

One last thought after perusing the manual... Have you experienced the
unit overheating? ...

No - I haven't let it run very long.

Max. rating of connected Power Tool = 3.7 A - Note: When the suction
power adjuster [1-7] is adjusted to the lowest suction power (see page
10, chapter Settings - Adjusting the suction power) the maximal rating
of a connected power tool can be 9.1 Amps.
===

It doesn't say whether this load is being sensed by the over
temperature alarm but I think it might be. Did your neighbor have
something a bit too greedy plugged into it?

The vac plus the connected load can't exceed 12A. Maybe the sensor on
the motor is a switch that interrupts both & its limit is 12A.

The neighbor has experienced shut-off with no connected load.

I've never felt very strongly that the bearings are the problem - they
just don't seem tight enough to cause that much draw (5.6A on low speed
vs 2.9 spec'ed). But it was the only thing that I thought of.

Another thing that I just thought of was damaged field winding. I.e.,
adjacent turns shorted, reducing the field, and drawing more current. I
don't know if that makes sense, if it ever happens, or how to test for it.

The motor-fan unit has fragile fans pressed on both ends, has a housing
that is glued or heat-welded together, and is just not going to be
explored. I'm about ready to pull the plug and have the neighbor order
a new one.

Bob