MIL-PRF-22885H
4.7.29 Mechanical endurance (see 3.34). Unless otherwise specified (see 3.1), switches shall be tested as
follows:
a. The switches shall be subjected to 5,000 cycles of operation (see 6.4.12) at -55°C ±2°C, 10,000 cycles of
operation at 85°C ±2°C, and 35,000 cycles of operation at room temperature. The cycling rate shall not
exceed 100 cycles of operation per minute and shall not be less than 10 cycles of operation per minute.
Each cycle of operation shall be the movement of the actuating means through the entire range of its travel
(from free position to full overtravel position and return to the fully released position) causing the switch
contacts to change from one position to another and then return to their original position. All switches
except those with push-pull operation shall be returned from their depressed position solely by the internal
mechanism of the switch. Switches shall be continuously monitored to determine whether any contact has
failed to open or close its individual circuit in proper sequence. Lamps shall not be energized.
b.
After tests are conducted as specified in 4.7.29a, a lamp retention test plug in accordance with figure 2 shall
be inserted (to complete engagement) and withdrawn five times. The test plug shall then be installed and
the lens held so that the base on the test plug points directly downward.
c.
After tests are conducted as specified in 4.7.29b, a modular switch assembly, as applicable, shall be
completely engaged and removed from the modular indicator light assembly a minimum of 10 times. The
lens lampholder assembly shall be completely removed, relamped, and installed a minimum of 100 times.
After the tests, the switch shall be examined for any physical damage, that is sticking of switch actuator,
loose latching of lens assembly, or broken, deformed clips or springs.
4.7.30 Intermediate current (when specified) (see 3.1 and 3.35). One throw of each pole of the switches under test
shall be connected into a circuit having a 27 V dc +3 V dc, -0 V dc source and a load consisting of the coil of relay
M5757/10-039 of MIL-R-5757/10, or equivalent. Switch performance during the test shall be continuously monitored
by a device which indicates failure of the relay to close and open during each cycle of operation. Unless otherwise
specified (see 3.1), the number of operations shall be 50,000 cycles. The switch shall be cycled by a mechanical
actuating device. During each cycle of operation, the actuating member of the switch shall be moved once to each
extreme of its travel. Double-throw switches shall be tested with half of the sample lot controlling the load with the
normally open contacts and half controlling the load with the normally closed contacts. Each multipole switch shall be
connected with all normally open circuits loaded simultaneously or all normally closed circuits loaded simultaneously.
The frequency of actuation shall be compatible with the time response characteristics of the relay monitoring device.
Prior to testing, each switch shall be subjected to a 24-hour minimum conditioning in air at the maximum rated
temperature. The test shall then be performed at the following operating temperatures:
a.
Twenty-five percent of the test cycles at the minimum temperature specified.
b.
Fifty percent of the test cycles at room ambient temperature.
c.
Twenty-five percent of the cycles at the maximum temperature specified.
Switch contact resistance shall be measured following the test using the electrical parameters of the minimum current
test load. Three measurements shall be made on each contact subjected to the intermediate current test.
4.7.31 Low level circuit (when specified) (see 3.1 and 3.36). Switches shall be tested as specified in method 311
of MIL-STD-202. The following details shall apply:
a. Contact load: Each set of normally open and normally closed contacts shall be connected to individual loads.
b.
Operate cycles: Fifty thousand at a rate not to exceed 60 cycles per minute with "ON" and "OFF" times
approximately equal.
c.
Operating temperatures:
(1)
Twenty-five percent of the test cycles at the minimum temperature specified.
(2)
Twenty-five percent of the test cycles at room ambient temperature.
(3)
Fifty percent of the cycles at the maximum temperature specified.
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