MIL-DTL-3950J
4.8.10 Mechanical endurance (see 3.6.9). The switches shall be subjected to 40,000 cycles of
operation. The following details shall apply:
+0°C
a. Switches shall be maintained at a temperature of -65C° -4°C for a period of at least two hours with
the contacts open. At the conclusion of this period all "on" positions shall be tested using a pilot
circuit with parameters of 28 Vdc maximum and 100 milliamperes maximum. Failure to turn "on"
on the first operation shall constitute failure.
b. One half of the cycles shall be -65C°+4°C while the other half of the cycles shall be at +71 +0°C .
0°C
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- °C
-
c.
A cycle shall be the movement of the toggle lever from one extreme position to the other extreme
position and return to the original position.
d. Cycling rate shall be 10 cycles per minute (cpm) to 18 cpm. At the manufacturer's option, a faster
rate of cycling, up to 60 cpm, may be used.
e. Lever-lock switch handles shall be tested for 20,000 actuations, at room ambient conditions, by
pulling the lever to its fully extended position and then permitting it to return to its fully retracted
position without operation of the switches, at a maximum of 60 cpm.
f.
With the toggle lever in the unlocked position, lever-lock switches shall be tested with the toggle
lever moving through all positions.
g. Momentary switches shall return from their momentary position(s) solely by the internal
mechanism of the switch.
4.8.11 Electrical endurance, electrical overload, intermediate current, low level life, and temperature
rise (see 3.6.10). The following conditions and exceptions shall apply:
a. Test switches shall be mounted by their normal mounting means against a metal plate. Insulators
shall not be interposed between the switch case and the metal plate or between the metal
actuator of the actuating machine and the switch toggle.
b. The metal mounting plate, one side of the power supply, and the metal actuator of the actuating
machine shall all be connected to a common ground through a three ampere fuse in accordance
negative side of the power supply shall be grounded. The test switch shall be connected to the
power source and test load using a ½ foot to 6 feet length of wire as specified in table VI.
c.
The test voltage magnitude and electrical frequency shall be maintained within the tolerances
specified when the test voltage is measured at the switch terminals. Each operation of the switch
shall be monitored to determine whether any contact has failed to open or close its individual
circuit in proper sequence. Each failure shall be recorded and reported. Monitoring circuit shall
not shunt switch contacts or inductive components in the test circuit.
d. One throw of each pole of the switch shall be connected to an independent test circuit meeting
the specified conditions. Multipole switches are to be tested with a load per pole and with
opposite line polarity on adjacent poles in accordance with figure 2. For double-throw switches,
one-half the switches shall be tested with the load circuit connected to one throw and the
remaining half of the switches shall be tested with the load circuit connected to the other throw.
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