MIL-DTL-26126C
4.6.8 Vibration.
4.6.8.1 Vibration (endurance, see 3.5.7.1). Relays shall be tested in accordance with method 201 of
MIL-STD-202. The following details and exceptions shall apply:
a. Mounting method: Rigidly mounted by normal mounting means. Connections to the
relay shall be made by attaching flexible stranded wires to the relay terminals.
b. Electrical load conditions:
(1) The relay S and G terminals shall be energized with 29 V dc during each 4-
hour vibration cycling period. The relay contact circuit (T and P terminals)
shall be continuously monitored for closing in accordance with method 310 of
MIL-STD-202, test circuit B, test condition A.
(2) With the relay S and G terminals de-energized, the relays shall be vibrated for
1 hour in each direction. The terminals shall be monitored as above.
c. Duration of vibration: Included in b.
d. Directions of motion: Two; both horizontal. One in line with the long axis and the other
at right angles to the long axis.
e. Measurement after vibration: Calibration as specified in 4.6.3.
4.6.8.2 Vibration (calibration) (see 3.5.7.2). The time-voltage characteristics of the relay shall be
measured at vibration frequencies of 0, 10, 20, 30, 40, 50, and 55 Hz and at any resonant frequency or
frequencies within this range, with the amplitude adjusted to .03 inch (0.8 mm). The relay shall be
vibrated through each of the three mutually perpendicular axes; however, if the relay contains a movable
plunger, the plunger travel axis shall always be in a horizontal plane. The relay shall be vibrated as
follows:
a. Mounted feet down in a horizontal plane, with the vibration applied in a horizontal plane
through the long axis of the relay.
b. Mounted as above, except that it shall be rotated 90° from position a. Vibration shall be
applied in a horizontal plane at right angles to the long axis of the relay.
c. Mounted with the mounting feet in a vertical plane. Vibration shall be applied in a
horizontal plane 90° from the long axis of the relay.
Following the test, the relay shall be tested for pickup voltage as specified in 4.6.3.1.
4.6.9 Low temperature altitude (see 3.5.8). The relay shall be subjected to a temperature of -55°C
±2°C for 5 hours at a pressure corresponding to an altitude of 50,000 ± 2,000 feet. While still at this
temperature and pressure, 28 V shall be applied for 2 minutes. Immediately following, calibration shall be
conducted as specified in 4.6.3.
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