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

3.12.8 Coil transient suppression (applicable to dc operated relays with coil transient suppression diodes) (see

4.8.7.8). Coils of dc operated relays shall not generate a back EMF greater than that specified (see 3.1).

3.13 Thermal shock (see 4.8.8). Insulation resistance, turn-on and turn-off voltages or currents, and turn-on and

turn-off times shall meet the requirements of 3.10, 3.12.4, and 3.12.6, respectively, at each temperature extreme.

Following the temperature excursions, there shall be no cracking, peeling, or flaking of the finish; dielectric

withstanding voltage shall meet the requirements of 3.11.

3.14 Shock (specified pulse) (see 4.8.9). Unless otherwise specified (see 3.1), there shall be no opening of closed

contacts in excess of 10 microseconds (�s) and there shall be no closure or bridging of open contacts in excess of 1

�s and no evidence of mechanical or electrical damage.

3.15 Vibration (see 4.8.10). Unless otherwise specified (see 3.1), there shall be no opening of closed contacts in

excess of 10 �s and there shall be no closure or bridging of open contacts in excess of 1 �s and no evidence of

mechanical or electrical damage.

3.16 Acceleration (unless otherwise specified, see 3.1) (see 4.8.11). The contacts of the relay shall remain in the

de-energized position with no control signal applied and in the energized position when control signal is applied.

3.17 Terminal strength (see 4.8.12). There shall be no evidence of loosening or breaking of the terminals, nor

shall there be any other damage which would adversely affect the normal operation of the relay. Bending of terminals

shall not be construed as damage. The glass criteria of 3.29 does not apply here.

3.18 Magnetic interference (when specified, see 3.1) (see 4.8.13). The specified pickup, hold, dropout, and turn-

on and turn-off values (voltages) shall meet the requirements specified in 3.12.2, 3.12.4, and 3.12.5.

3.19 Coil life (see 4.8.14). There shall be no evidence of damage. The manufacturer shall notify the qualifying

activity when changes to the coil design or manufacture occur. The Qualifying Activity reserves the right to invoke the

coil life test prior to shipment of product as part of this requirement.

3.19.1 Coil endurance (see 4.8.14.1). The coil resistance shall be as specified (see 3.1).

3.20 Resistance to soldering heat (see 4.8.15). There shall be no damage which would adversely affect normal

operation of the relay.

3.21 Salt spray or atmosphere (corrosion) (see 4.8.16). There shall be no evidence of breaking, cracking,

chipping, or flaking of the finish, nor exposure of the base metal, due to corrosion, which would adversely affect the

application or performance characteristics of the relay.

3.22 Overload (applicable to high level relays only) (see 4.8.17). The voltage drop across closed contacts shall be

less than or equal to 5 percent of the applied load voltage and the voltage across open contacts shall be 95 percent

or more of the applied load voltage. The case-to-ground fuse shall remain electrically continuous.

3.23 Life (see 4.8.18). Unless otherwise specified (see 3.1), for low level testing, the contact miss detector's

monitoring level shall be less than or equal to 100 ohms. For high level testing, the contact miss detector's

monitoring level shall be less than or equal to 5 percent of the applied load voltage and the voltage across open

contacts shall be 95 percent or more of the applied load voltage. Unless otherwise specified, the static contact

resistance following cycling shall be no greater than twice the initial specified contact resistance requirement. There

shall be no mechanical or electrical failure. Welding of contacts, failure to make, carry or break the load, or failure of

the fuse connected between case and load system ground or neutral shall constitute a failure. Relays indicating

failure, not verified per a failures verification procedure approved by the qualifying activity, may be returned to test.

During post life tests, failure of a diode, transistor, or FET coil driver shall constitute a failure.