Energy Guide

Page 84 of 104 Report No.: HK2107050725-SR
UL 507
Clause Requirement + Test Result - Remark Verdict
TRF No. UL507A
67.3.2 The transformer shall be operated as described in
the Temperature Test in Section 46, except that
the load shall be 50 percent of the rated value, until
the core, or surface temperatures if encapsulated,
stabilize. After stabilization, the load shall be
adjusted until 200 percent of rated secondary
current is reached. After 2 minutes of operation,
the load shall be readjusted, if necessary, to
restore the current to 200 percent, but no further
adjustment is to be made thereafter. The duration
of this overload shall be 30 minutes. The load is
then to be restored to the original 50 percent of
rated value. It shall be held at that value until the
core temperature again stabilizes or until the
temperature drops to within 5°C (9°F) of the
original stabilized 50-percent load-current
temperature (whichever occurs first). This
temperature value shall be compared with the
original 50-percent load stabilized condition, as
specified in 67.3.1. Then, the secondary load shall
be removed. With the primary energized, the
secondary voltage (s) shall be measured and
compared with the original output voltage
measurements.
N/A
67.3.3 When the core of the transformer is not accessible
for direct temperature measurement (due to the
transformer construction or reasons such as
encapsulation or filling with electrical insulating
material), the surface of the transformer enclosure
shall be used. The portion of the enclosure surface
used to measure this tempersture shall be the
hottest spot occurring in the 100 percent load
heating test
N/A
67.3.4 A protective device, when provided, shall be
bypassed when the device opens while the load is
adjusted after the surface temperatures have
stabilized.
N/A
67.4 Repeated dielectric voltage-withstand test N/A
67.4.1 Following the Overload Test in 67.3, the
transformer shall be subjected to a repeated
dielectric voltage-withstand test. The test potential
shall be 65 percent of the value originally specified.
After this test, the transformer shall perform as
intended.
N/A
68 Thermal Aging N/A