Player Piano Motor Case Temperature
By Paul Rumpf
Dave Krall asks about motor case temperatures. The lowest temperature
insulation class is Class A which is rated at 105 degree C. [221 F.].
This allows a 65 degree C. temperature rise at an ambient temperature
of 40 degrees C. It is not unusual for a motor to be too hot to touch.
Obviously, cooler running is better. The effectiveness of cooling fans
is proportional to the cube of the speed. For 6- or 8-pole motors
[1150 or 860 rpm], shaft mounted fan blades can be practically useless.
It is most unlikely that a split phase motor will even turn if there
is a short-circuited turn in the winding. The local heat generated in
a short-circuited turn will rapidly progress to the shorting of the
Hope this helps.
(Message sent Fri 13 Sep 2013, 00:39:58 GMT, from time zone GMT+1000.)