MIL-DTL-28788C
4.7.12 Vibration (see 3.16). Switches shall be tested for vibration grade 1, 2, or 3 (as applicable,
see 3.1) in accordance with MIL-STD-202. The following details shall apply
a. Mounting of specimens Switches shall be mounted on a rigid metal fixture by their normal
mounting means.
b. Electrical load conditions The electrical load shall consist of a monitoring circuit.
c. Test condition letter.
1. For vibration grade 1 Method 201 (10-55 Hz).
2. For vibration grade 2 Method 204, test condition A (10-500 Hz).
3. For vibration grade 3 Method 204, test condition B (10-2,000 Hz).
d. Measurements during test All checks for contact disturbance shall be conducted with the
switches being cycled between actuation and deactuation at a switching rate of no more than
10 cycles per minute, with the flow rise and decay rate not exceeding 1 percent per second,
within 10 percent of the switching points. The entire frequency range shall be traversed as
required by the applicable test method in MIL-STD-202. A minimum of two cycles of
operation shall be recorded at each of the following frequencies. 10, 20, 40, and 55 (grade 1)
or 2,000 Hz, as applicable (grades 2 and 3). Contact disturbance shall not exceed 250
microseconds when the flow pressure is within 10 percent of the switching point. At all other
time, the contact disturbance shall not exceed 10 microseconds. Contact disturbance shall
be monitored by any suitable means that will provide a permanent record of the contact
disturbance at the above test frequencies. Approximately 50 actuations in each of the three
mutually perpendicular planes shall be recorded and submitted with the test report. Following
the test, switches shall be examined for evidence of broken, displaced, or loose parts, and
operating points shall be within tolerances specified (see 3.1).
MIL-STD-202. The following details and exception shall apply:
a. Test condition A.
b. Measurement before and after cycling Not applicable.
c. Examination after test The flow settings shall be within the tolerances specified (see 3.1 and
6.1). Switches shall be examined for mechanical and electrical damage, and loosening of
rivets and other fastening devices, and switches shall be within tolerances specified.
MIL-STD-202. The following details and exceptions shall apply:
a. Polarization voltage During steps 1 to 6 inclusive, a polarizing voltage of 100 volts dc shall
be applied between all terminals tied together and the metal panel. The negative polarity
shall be applied to the metal panel.
b. Steps 7a and 7b Not applicable.
c. Loading voltage Not applicable.
d. Final measurements After high humidity, insulation resistance shall be measured as
specified in 4.7.15. At the end of the drying period, insulation resistance shall again be
measured as specified in 4.7.15.
e. Examinations during final measurement and after test Switches shall be examined for
evidence of corrosion, breaking, cracking, and spalling.
MIL-STD-202. The following details shall apply:
a. Test condition B.
b. Points of measurement Between all terminals and frame or ground.
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