MIL-PRF-28776 Relays, Hybrid, Established Reliability, General Specification ForThis specification establishes the general requirements for relays that use a combination of solid state circuit input elements functioning with an electro-mechanical relay that performs the switching functions associated with control system applications \(see 6.1\). These relays are designed to operate in low and medium power switching circuits with contact ratings up to 1 ampere alternating current \(ac\) or direct current \(dc\). The failure rate level is established at a confidence level of 90 percent for qualification and 60 percent for maintenance of qualification based on 100,000 cycles at +125┬░C under rated load conditions specified herein. Excludes time delay relays. CAUTION: The use of any coil voltage less than the rated coil voltage will compromise the operation of the relay. CAUTION: Pick-up, hold, and dropout voltages are for test purposes only and are not to be used as design criteria. For additional application and caution information, see 6.1.

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MIL-PRF-28776F

4.8.10.2 Vibration (random). Relays shall be tested in accordance with method 214 of MIL-STD-202. The

following details and exceptions shall apply:

Method of mounting: As specified in 4.8.9a.

Electrical-load conditions: For qualification and group C inspections, relays shall be tested with the relay

energized at rated voltage for 15 minutes and with the coil de-energized for 15 minutes, in each of three

mutually perpendicular (x, y, and z) directions. When applicable to group A inspection, the test time shall

be 3 minutes for each state described above. Contacts shall monitored as specified in 4.8.10.2d.

Test condition: G (0.4 G2/Hz, 23.91 rms G).

Tests during vibration: As specified in 4.8.9d.

Examination after test: As specified in 4.8.10.1f.

4.8.11 Acceleration (unless otherwise specified, see 3.1 and 3.16). Relays shall be tested in accordance with

method 212 of MIL-STD-202. The following details and exceptions shall apply:

Mounting of specimens: As specified in 4.8.9a.

Test conditions: Unless otherwise specified (see 3.1), test condition A, 50 G's, (acceleration shall be

applied in each direction along three mutually perpendicular axes (x, y, and z) of the specimen; one axis

shall be in the direction most likely to cause malfunction). In each direction, the coil shall be de-energized

for 5 minutes, rated coil voltage shall be momentarily applied, and the voltage shall be reduced to the

maximum ambient pickup voltage as specified (see 3.1) for 5 minutes. Contacts shall be monitored for

proper position.

Examination after test: As specified in 4.8.9e.

4.8.12 Terminal strength (see 3.17). Relays shall be tested in accordance with method 211 of MIL-STD-202 in

accordance with the following, as applicable. Unless otherwise specified herein, two terminals of each discrete

design, size, and configuration shall be tested; however, if there be only one of such design, size, and configuration, it

shall be tested.

4.8.12.1 Pull test (all terminal types). Terminals shall be tested as specified in test condition A; the force shall be

as specified (see 3.1).

4.8.12.2 Bend test (all terminal types). Terminals shall be tested as specified in test condition B (two bends) or C,

as applicable. Loads for test condition C shall be as specified (see 3.1).

4.8.12.3 Twist test (wire lead terminals only) (not applicable to relays with spreader mounting pads or leads less

than .50 inch (12.7 mm) in length). All terminals shall be tested as specified in test condition D, except during

application of torsion, each terminal shall be rotated 45� in one direction, then returned to start; rotated in opposite

direction 45�, then returned to start. Each terminal shall be subjected to two such rotations and returns. Each

terminal shall be held at a point .75 inch (19.05 mm) from the point of emergence from the relay, or terminal end for

relays with terminals less than .75 inch (19.05 mm), and in one plane shall be bent 20� �5� in one direction, then

returned to start; bent in opposite direction 20��5�, then returned to start. This procedure shall then be repeated in

the perpendicular plane. Following these tests, relays shall be examined for evidence of loosening or breaking of the

terminals and other damage that could adversely affect the normal operation of the relay; the requirements of 3.29

are not applicable.