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

4.8.13 Magnetic interference (when specified, see 3.1 and 3.18). The relay under test and eight similar relays

shall be mounted in the same physical orientation by nonmagnetic means, as shown on figure 8. Unless otherwise

specified, grid-spaced relays shall be mounted so that all terminals are positioned in the closest possible grid pattern.

Unless otherwise specified, the spacing between terminals and tops of adjacent terminals shall be as shown on figure

8. Pickup, hold, dropout, turn-on, and turn-off voltages shall be measured on the relay under test as specified in

4.8.7.2, 4.8.7.4, and 4.8.7.5 with the coils of the eight outer relays energized at rated voltage (the magnetic polarity of

each relay shall be similarly oriented). This measurement shall be repeated with the coils of the eight outer relays de-

energized.

4.8.14 Coil life (unless otherwise specified, see 3.1) (see 3.19). Relays shall be tested for 1,000 hours as follows

Relays may be mounted as specified in 4.3.6. Each contact terminal shall be connected as specified in

During the maximum temperature portion of the test, rated coil supply voltage (see 3.1) shall be applied

continuously and at least half of the normally open contacts shall carry rated current. During room

temperature and minimum temperature exposures, the coil circuit shall be de-energized and contacts shall

not be loaded. Ambient temperatures shall be varied as shown on figure 9, with heating and cooling rates

not to exceed +1�C per second average. The portion of the cycle run at minimum temperature shall be

approximately 10 percent of the test cycle time.

After the first 100 hours, and while still at the low temperature extreme, contact resistance (or voltage drop)

and turn-on and turn-off time shall be measured as specified in 4.8.7.1 and 4.8.7.6 and the values shall be

recorded. Measurements of coil current as specified, and contact resistance as specified in 4.8.7.3 and

4.8.7.1, shall be taken at room temperature initially, then again after 250 �25, 500 �25, and 750 �25 hours

and the values shall be recorded. Pickup, hold, dropout, turn-on voltage or current, and turn-off voltage

measurements shall be made as specified in 4.8.7.2, 4.8.7.4, and 4.8.7.6, respectively during the last

temperature cycle after allowing the relay to stabilize, deenergized at each of the temperature extremes,

and the values shall be recorded.

After the relay(s) have been subjected to the coil life temperature cycles, measurements shall then be taken

at room temperature of dielectric withstanding voltage, insulation resistance, contact resistance (or contact

voltage drop), coil current, turn-on and turn-off time, and contact bounce as specified in 4.8.6.1, 4.8.5,

4.8.7.1, 4.8.7.3, 4.8.7.6, and 4.8.7.7, respectively. Relays shall then be examined for evidence of damage.

Following the test, the coil current or resistance, as applicable, shall be measured in accordance with 3.12.3

and shall be as specified (see 3.1).