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Table 37.1 Continued
Material and component parts Degrees
CF
20. Class 220 (R) insulation systems on coil windings of a transformer
Thermocouple method 180 356
Resistance method 190 374
21. Class 105 (A) motor coil insulation systems
A. In an open motor
Thermocouple method 90 194
Resistance method 100 212
B. In a totally-enclosed motor
Thermocouple method 95 203
Resistance method 105 221
22. Class 130 (B) motor coil insulation systems
A. In an open motor:
Thermocouple method 110 230
Resistance method 120 248
B. In a totally-enclosed motor
Thermocouple method 120 248
Resistance method 125 257
a
The temperature limitations on phenolic composition and on rubber and thermoplastic insulation do not apply to a compound
that has been investigated and found to have acceptable heat-resistant properties.
b
A short length of rubber- or thermoplastic-insulated flexible cord inside a converter may be exposed to a temperature of more
than 60°C (140°F) if supplementary insulation acceptable for the measured temperature and of adequate dielectric properties is
employed on each individual conductor.
c
A capacitor that operates at a temperature rise of more than 90°C (140°F) may be judged on the basis of its marked
temperature limit. In any case, the measured temperature shall not exceed the temperature rating of the capacitor.
d
Unless a thermosetting compound, the maximum sealing compound temperature, is 15°C (27°F) less than the softening point
of the compound as determined in accordance with the Test for Softening Point by the Ball- and Ring-Apparatus, ASTM E28-
1992.
e
At a point on the surface of a coil where the temperature is affected by an external source of heat, the temperature measured
by means of a thermocouple may be 5°C (9°F) higher than that indicated, if the temperature of the coil as measured by the
resistance method is not more than that specified.
f
A temperature of 85°C (185°F) is acceptable if the stack assembly is insulated with phenolic composition or other insulating
material acceptable for a temperature of 150°C (302°F).
g
The limitation does not apply to a material that has been investigated and found acceptable for a higher temperature limit. A
component that operates at a temperature exceeding 100°C is to be judged on the basis of the manufacturer’s rating.
h
Contacts of silver or a silver alloy in components that function in a high ambient are acceptable, without any additional tests if
they do not attain a temperature higher than 100°C (212°F) when the device is tested at the ambient temperature in question. If
the contacts attain a temperature higher than 100°C but no higher than 150°C, they shall perform acceptably when subjected to
the overload and endurance tests conducted at the high ambient temperature in question.
JANUARY 27, 1995UL 45852
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