Dielectric Voltage-Withstand Test - Century UL 1086 Manual

FEBRUARY 1, 1996
37.7 In using the resistance method, the windings are to be at room temperature at the start of the test.
The temperature rise of a winding is to be calculated from the formula:
in which:
∆ t is the temperature rise in °C;
R is resistance of the coil at the end of the test in ohms;
r is resistance of the coil at the beginning of the test in ohms;
t is room temperature at the beginning of the test in °C;
1
t is room temperature at the end of the test in °C; and
2
k is 234.5 for copper, 225.0 for vertical conductor grade (EC) aluminum. Values of the constant
k for other grades must be determined.
37.8 Thermocouples are to consist of wires not larger than No. 24 AWG (0.21 mm
be noted that when thermocouples are used in the determination of temperatures in connection with the
heating of electrical devices, it is common practice to employ thermocouples consisting of No. 30 AWG
2
(0.05 mm ) iron and constantan wires and a potentiometer-type indicating instrument; and such
equipment is to be used whenever referee temperature measurements by thermocouples are necessary.
37.9 An appliance is to be mounted in an enclosure of nominal 3/8-inch thick, black-painted plywood,
consisting of a bottom, a back, and two sides; the enclosure is to include a top for an undercounter,
recessed or convertible appliance. Each of these areas is to be in as intimate contact with the
corresponding surface of the appliance as the configuration of the latter permits. Temperatures are to be
measured at points on each of these enclosing surfaces.
37.10 If the appliance incorporates a reel for the power-supply cord, one third of the length of the cord is
to be unreeled for the temperature test.
37.11 A motor-protective device shall not operate during the normal temperature test.

38 Dielectric Voltage-Withstand Test

38.1 An appliance shall withstand for 1 minute without breakdown the application of a 60-hertz essentially
sinusoidal potential between live parts and dead metal parts, and between live parts of opposite polarity
for a test on a capacitor used for radio-interference elimination or arc-suppression, with the appliance at
the maximum operating temperature reached in normal use. The test potential shall be:
a) One thousand volts for an appliance employing a motor rated 1/2 horsepower or less. See
16.4.
b) One thousand volts plus twice rated voltage for an appliance employing a motor rated more
than 1/2 horsepower. See 16.4.
HOUSEHOLD TRASH COMPACTORS - UL 1086 43
2
). However, it should