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.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13

MIL-PRF-28776F

4.4.1 Qualification. Qualification shall be granted at the "L" or "M" failure rate initially and shall be based on results

of the qualification inspection specified in table II. A certification of construction to the materials requirements of 3.4,

and the design and construction requirements of 3.5 shall accompany the submission of qualification inspection

results to the qualifying activity.

4.4.1.1 Sampling plan. The number of relays to be subjected to qualification inspection shall be as specified in

table II. The sample shall be selected from a production run and shall be produced with equipment or procedures

normally used in production. The qualification sample shall be as defined in table II.

4.4.2 Inspection routine. Sample units shall be subjected to the qualification inspection outlined in table II, in the

order shown, except that groups Q2 through Q7 may be conducted concurrently. All sample units shall be subjected

to the tests in Q1. These sample units shall then be divided into six groups as specified in table II and subjected to

the inspection specified for their particular group.

4.4.3 Failures. Failures in excess of those allowed in table II shall be cause for refusal to grant qualification

approval.

4.4.4 Failure-rate level and quality level verification.

4.4.4.1 FR qualification. FR qualification shall be in accordance with the general and detailed requirements of

MIL-STD-690, MIL-STD-790 in its entirety, and the following details:

Procedure I - Qualification at the initial FR level. The manufacturer may qualify his products to failure rate

levels "L" or "M" initially.

Procedure II - Extension of qualification to lower FR levels. To extend qualification to a lower FR level (see

table III), data from two or more styles of similar construction may be combined.

Procedure III - Maintenance of FR level qualifications. Maintenance period of table IV shall apply.

Regardless of the number of production lots produced during this period, the specified number of life test unit

operations shall be accumulated to maintain qualification. If there is no production, see 4.5. The

manufacturer shall preselect the sampling plan to be used during the maintenance period from table IV. In

the event that failures occur exceeding the sampling plan selected (C = number), the failure rate of the

product shall be increased one level or the product removed from the Qualified Products List.

Noncompliance corrective action shall be in accordance with 4.7.3.3.