MIL-PRF-11021H
while still at the temperature, the switch assembly shall be subjected to the continuous current
tests as specified in TABLE III for not less than 60 minutes. The switch assembly shall
subsequently be subjected to the ultimate trip currents for not more than 60 minutes.
4.6.4 Circuit breaker high temperature reclosing test. To determine conformance to
3.4.4, the switch assembly shall be conditioned for 5 hours at 180 + 5°F and, while still in
ambient air at that temperature, a 60 ampere current shall be passed through the circuit breaker
until it trips. The switch assembly shall be allowed to stand in ambient air at the same
temperature until contacts reclose or 30 minutes have passed. If the contacts do not close within
the 30 minutes, the switch assembly has failed the test.
4.6.5 Circuit breaker no-current trip temperature test. To determine conformance to
3.4.5, the switch assembly shall be placed in a temperature-controlled oven provided with means
of determining whether contacts are open or closed. The oven shall be maintained at 265 + 5°F
for a minimum of 5 hours, after which a determination of contact position shall be made. The
circuit breaker shall not trip during this test.
4.6.6 Circuit breaker speed of operation test. To determine conformance to 3.4.6, the
switch assembly shall be connected in the circuit shown in Figure A2 and the circuit calibrated
for each value of current employed. Calibration shall consist of opening switch S2, closing
switch S1, and varying the load resistance (R2) until the desired value of current is registered on
the ammeter. Subsequently, the S1 switch shall be opened, the S2 switch closed, and the time
required for the circuit breaker to trip and reset shall be recorded for each of the current
overloads specified in TABLE I.
4.6.7 Circuit breaker overload test.
4.6.7.1 Apparatus. Test apparatus shall include timers with resolution to one
millisecond, a controllable load resistance for adjusting the demand current, switches, wiring,
components, and fixtures necessary to conduct the test.
4.6.7.2 Test procedures. The switch assembly shall be connected as shown in Figure A2,
and the circuit calibrated as specified in 4.6.6. Closure of switch S2 shall initiate the test. The
first five cycles are pre-conditioning, and the times shall not be recorded. Upon starting the sixth
cycle, two timers shall be used and both timers shall be started simultaneously. Timer 1 shall
measure accumulated conduction time for cycles six through ten. Timer 2 shall measure the total
time from the start of the sixth cycle to the end of the tenth cycle. A cycle consists of the time
interval from the start of conduction to the re-initiation of conduction after tripping. The test
shall be conducted with demand-currents of 26, 30, 50, 120, and 200 amperes. Tolerance on
demand currents is + 5% of specified value. Effective current values shall be calculated by
means of the following equation to determine conformance to 3.4.7:
I = i t /T
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