MIL-DTL-19648E
d. At the end of the required vibration period in each plane, with the frequency at maximum of range,
energize the relay at rated heater input and measure operate time to first evidence of chatter and
duration of chatter. The time to the first sign of chatter shall be not less than 80 percent of the
normal operate time, and the chatter duration not more than 25 percent of the normal operate time.
e. At the conclusion of the test, insulation resistance, dielectric withstanding voltage at sea level,
contact resistance (or contact voltage drop) and normal operate time shall be measured as
specified in 4.7.6, 4.7.5.1, 4.7.3.1, and 4.7.3.2, respectively.
4.7.12.2 Level 2. Relays shall be tested in accordance with details specified in table VIII and 4.7.12.1,
except that test condition A of method 204 shall be used. During the first three cycles of the frequency
band in each direction, a light dc load (0.01 ampere maximum and 6 volts maximum) shall be applied to
the contacts and 90 percent of the actual minimum hold-in voltage shall be applied to the heater. The
relays shall be carefully observed for evidence of resonance during this portion of test. If no resonance is
detected, the next three cycles shall be run with the relay stabilized at rated voltage and the last three
cycles unenergized. If resonance is found, the frequency shall be adjusted to the maximum resonance
and the relay vibrated for the period of time normally required for the next three cycles energized, three
cycles unenergized. Then, with vibration at maximum point of resonance, energize the relay at rated
heater input and measure operate time to first sign of chatter and duration of chatter. The time to the first
sign of chatter shall be not less than 80 percent of the operate time, and the chatter duration not more
than 25 percent of the operate time. The frequency band (or bands) over which resonance occurs shall
be recorded.
4.7.12.3 Level 3. Details shall be as specified in 4.7.12.2 except test condition B shall apply.
4.7.12.4 Level 4. Details shall be as specified in 4.7.12.2 except test condition D shall apply.
4.7.13 Moisture resistance (see 3.16). Relays shall be tested in accordance with method 106 of MIL-
STD-202. The following details and exceptions shall apply:
a. Initial measurement - Insulation resistance shall be measured at room ambient temperature at the
end of the initial drying period (see 4.7.6).
b. Polarization - During steps 1 to 6 inclusive, a polarizing voltage of 100 volts dc shall be applied
between all terminals tied together and the metal mounting (noncorrosive) panel. The negative
polarity shall be applied to the metal panel. Steps 7a and 7b are not applicable.
c. Loading voltage - Not applicable.
d. Final measurements - Insulation resistance shall be measured for first article tests after 1 hour of
drying at room temperature at the end of last cycle and dielectric withstanding voltage, normal
operate time, contact resistance (or contact voltage drop), and corona. Insulation resistance shall be
measured for quality conformance inspection tests.
4.7.14 Overload (see 3.17). Unless otherwise specified (see 3.1), the relay contacts shall make and
break at rated voltage, the current specified in 4.7.14.1, 4.7.14.2, or 4.7.14.3, as applicable, for 50
operations each. At the end of the test, contact resistance (or contact voltage drop) and normal operate
time shall be measured as specified in 4.7.3.1 and 4.7.3.2, respectively.
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