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

4.8.2 Screening (see 3.7).

4.8.2.1 Internal moisture. Relays (coil de-energized) shall be held at +15�C to +25�C for a minimum of 30 minutes.

The insulation resistance of all contact pins to case only shall be measured and observed. The relay coil shall be

energized with 140 percent of rated voltage for a period of 2 minutes 30 seconds. 3/ The insulation resistance of all

contact pins to case only shall be verified a minimum of once each 30 seconds during this period and the lowest

value shall meet the requirements of 3.7.

4.8.2.2 Run-in.

High temperature. For qualification inspection only; relays shall be subjected to +125�C with rated supply

voltage on the coil for 1 hour. For group A testing, relays shall be subjected to +125�C; the test chamber

shall stabilize at +125�C after the specimens have been inserted into the test chamber. The test shall be

performed with rated supply voltage on the coil circuit for 15 minutes minimum for relays weighing 1 ounce

or less and 30 minutes minimum for relays weighing over 1 ounce but not more than .3 pound. The

specified pickup value (voltage) shall be measured to determine compliance with 3.1. While at this

temperature, the relays shall be subjected to a 2,500 cycle run-in test. The cycling rate shall be calculated

using the formulas below and the maximum turn-on and turn-off times as specified, see 3.1 for the relay

under test. Relays shall have the contacts loaded as follows: Open circuit load voltage 10 to 50 mV dc or

peak ac. The load current shall be 10 to 50 �A. The contact resistance or voltage drop, as applicable, of

each pair of mated contacts shall be monitored during 40 percent minimum of each "on" and each "off"

period. The monitoring equipment shall automatically turn off when a failure occurs, or shall record every

failure.

Low temperature. Following high temperature, for qualification only, relays shall be subjected to -65�C with

the coil or coils de-energized for 1 hour. For group A testing, relays shall be subjected to -65�C; the test

chamber shall stabilize at -65�C after the specimens have been inserted into the test chamber. The test

shall be performed with the coil de-energized for 15 minutes minimum for relays weighing 1 ounce or less

and 30 minutes minimum for relays weighing over 1 ounce but not more than .3 pound. At the end of either

period, the specified dropout value (voltage) shall be measured to determine compliance with 3.1. While at

this temperature, the relays shall be subjected to a 2,500 cycle run-in test in accordance with the procedure

outlined in 4.8.2.2a.

0.1



Maximum cycle rate

Maximum turn  on time  Maximum turn  off time

(cycles per sec ond )

(sec onds)

4.8.3 Solderability (see 3.8). Relays shall be tested in accordance with method 208 of MIL-STD-202. The

following detail and exception shall apply: All terminations of each part shall be tested.

4.8.4 Seal (see 3.9). Relays shall be tested in accordance with 4.8.4.1 as applicable. In case of dispute, method

1014 of MIL-STD-883, test condition B shall govern.

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3/ Wherever "coil shall be energized" is used herein, it is considered to include turn-on voltage applied.