MIL-DTL-3971F
4.4.6 Test methods.
4.4.6.1 Insulation resistance. The insulation resistance between terminals and case shall
exceed 100 megohms when subjected to method 302, test condition A of MIL-STD-202.
4.4.6.2 Electromagnetic compatibility. Grade A meters shall be subjected to methods CE102
and RE102 of MIL-STD-461.
4.4.6.3 Dielectric strength. Meters shall be subjected to method 301 of MIL-STD-202 for 60
seconds between the terminals and case with test voltage as specified.
4.4.6.4 Starting and stopping. The meter shall be energized as specified. Failure to start
within 10 seconds or stop within 120 seconds shall be cause for rejection.
4.4.6.5 Operating position. The meter shall be energized with applicable rated voltage and
frequency (see 4.3.7.2) and operated for a minimum of four hours in each of the following
positions:
a. Face up
b. Face down
c. Face up 45 degrees from horizontal
4.4.6.6 Vibration.
4.4.6.6.1 Normal vibration. While energized the meter shall be subjected to 4 cycles of
vibration, each of 15 minutes, in 3 mutually perpendicular axes with the frequency varied
logarithmically from 7 to 500 Hz and return to 7 Hz. The amplitude from 7 to 57 Hz shall be
0.06 inch (1.52 mm) double amplitude (maximum total excursion) and from 57 to 500 Hz the
acceleration shall be 10g's. The meter shall operate for one hour following vibration.
4.4.6.6.2 Extended vibration. Following normal vibration the meter, while energized, shall
be vibrated with an input acceleration level of 2g's as follows:
Frequency (Hz)
Axis
Time
Temperature
-32°C ± 2°C (-25.6° F ± 3.6°F)
60
Vertical
l0 hours
+23°C ± 10°C (73.4° F ± 18.0°F)
60
Vertical
30 hours
+68°C ± 2°C (154.4° F ± 3.6°F)
60
Vertical
l0 hours
The meter shall operate for 24 hours following extended vibration.
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