I tend to agree with Chet. The motors should be rated for continuous duty
and would be stated on the nameplate. If they are rated for intermittent
duty, then they are not suited for a spa.

I wouldn't be overly concerned about the ampere ratings on a new motor
compared to an older motor. The new motors are more efficient and have less
"Losses" then older motors. As long as FRAME, VOLTAGE, HP, RPM, and DUTY
are the same the motor should operate correctly.

Low voltage or too much of a workload will cause a motor to overheat. Have
you been using the same pump or did you get a new one? I hope that you are
not running the pump while it is dry.

The control box may be your problem. The contacts on the motor relay(s) may
be corroded and causing a lot of resistance to be in the motor feed and
consequently a low voltage condition. Try running the motor directly off of
an extension cord (One rated for the load) and see if it overheats.


John Grabowski
http://www.mrelectrician.tv



"Chet Hayes" wrote in message
om...
"1_Patriotic_Guy" wrote in message
link.net...
I appreciate all the help and guidance. These recent answers have been
clear and easy to understand. Hopefully this is my last question on
small
motors for a while (if not, I'll need more humor, but am willing to
learn).

Can anyone educate me on "Thermal Protection" Rating on electric motors.
Old motor is "AA", second motor canabalized from a friend's old spa is
C1
(works well on low speed, but overheats in 30 minutes to an hour on high
speed),
Store recommended and purchased motor is "MA" and overheats even on low
speed -- not good.

Tony & Ron, you got me to understand Insulation Class, Thanks, If
someone
can educate me on "thermal protection" ratings or point me in the right
direction to look, I should hopefully know enough to take the new motor
back
(it appears undamaged, just gets warm after use and shuts itself off,
electrical connections and windings look clean and new) and exchange for
the
correct motor. The salesman seemed clueless on these ratings and he is
the
"technical guy" for the store. By process of elimination, I'm guessing
the
ratings have something to do with why the motors are over-heating. I
can't
find an electric motor repair place in my area to take the motor in to
so I
am at the mercy of the spa store. I'd at least like to be knowledgable
so I
get the right motor.

The cord and control box are the other common links in the problem.
When I
moved the cord from the original motor to the others I examined it --
Condition look's good. Opened control box, some minor corrosion, from
damp
air over time but not sure what to check in here. Nothing looks badly
damaged, overheated or burned. I did remove a moderate sized cobweb
attached to one electrical component. If the next motor has problems I
will
have to suspect the control box. It seems easiest to try to get a new
motor
that matches the old on thermal protection (already matched all the
other
specs except minor difference on amps and 3.1 vs 3.5 as I understand it
shouldn't matter, just means newer motor is more efficient, correct me
if
I'm wrong), but "has the rating terminology for thermal protection
changed
over the last ten to fifteen years" (best guess at age of original motor
based on info on plate, hard to read). If someone can educate me I'll
at
least know what to look for in the way of thermal protection.

All the motors meet the specs you all explained for Insulation Class,
and
ambient temperature for where used (and match to the old motor).
Thermal
protection code on each is different.

Thanks in advance,
Andy

Replacing these motors is not rocket science. The fact that you have
replaced motors and they are not working has nothing to do with
thermal protection, which is a symptom and not the problem. If you
replaced it with the correct HP and speed, which any shop that sells
spa parts should be able to provide, then the motor should work.
There isn't anything particularly unique about these motors, the same
one will fit many spas. Have you checked the voltage on the motor
while it's running to make sure it's getting full voltage? And have
you inspected the pump to make sure it's turning freely and not
binding? Is the water flowing freely without obstruction? Those are
the only things that will cause it to overheat.