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48.2.2 Power-dissipating parts, electronic devices, and capacitors connected between traces having
reduced spacings are to be removed or disconnected in a manner that the spacings and insulations,
rather than the component parts, are subjected to the full dielectric voltage-withstand test potential.
48.3 Shorted trace test
48.3.1 Printed wiring board traces mentioned in 48.1.1 are to be short-circuited, one location at a time,
and the test is to be conducted as described in 48.2.1 and 48.2.2. As a result of this test, the overcurrent
protection associated with the branch circuit to which the converter or inverter is connected shall not open,
and a wire or a printed wiring board trace shall not open. If the circuit is interrupted by the opening of a
component, the test is to be repeated twice using new components as necessary.
Exception: Opening of an internal overcurrent protective device is an acceptable termination of the test,
and the test need not be repeated.
48.3.2 During the Shorted Trace Test the supply circuit is to have branch circuit overcurrent protection,
the size of which equals 125 percent of the input current rating (20 amperes minimum), except where this
value does not correspond with the standard rating of a fuse or circuit breaker, the next higher standard
device rating shall be used.
49 Burnout Test
49.1 General
49.1.1 A converter or inverter shall not emit flame or molten metal or become a risk of fire or electric
shock while operating as in the temperature test except under the conditions described in 49.2.1. With
reference to 49.3.1, the burnout test of the transformer shall be followed by a dielectric voltage-withstand
test, as required by 39.1(a). During each test all dead metal parts of the enclosure of the converter or
inverter are to be connected directly to ground, and:
a) The converter or inverter is to rest on a soft-pine surface covered with white tissue paper; and
b) A double layer of cheesecloth is to be draped over the converter or inverter.
Exception: A nonmetallic enclosure with exposed dead metal parts that are not likely to become
energized need not be grounded.
49.1.1 effective April 13, 1993
49.2 Relay and solenoid burnout
49.2.1 An electromagnetic relay or solenoid constructed as described in 6.19 is to be tested by blocking
the armature or the plunger in the de-energized position. The converter or inverter is then to be connected
to its rated source of supply and operated until burnout of the coil occurs or temperatures become
constant. During the test, the converter or inverter enclosure is to be connected directly to ground.
49.2.1 effective April 13, 1993
DECEMBER 14, 1993 UL 458 67
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