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

3.5.4 Coils. Coils shall be adequately insulated electrically from the contacts and the case. The resistance and

rated voltage (or current) shall be as specified (see 3.1). Unless otherwise specified (see 3.1), coils shall be

designed for continuous operation at maximum rated voltage and temperature.

3.5.4.1 Terminal identification. When specified (see 3.1), a bead of contrasting color shall be used to designate

the X1 (positive, if applicable) terminal (see figure 1 and MIL-STD-1285).

FIGURE 1. Symbols and marking for terminals.

3.5.5 Circuit diagram. The circuit diagram, as specified (see 3.1), shall be a terminal view. Circuit symbols shall

be in accordance with IEEE-315. For relays without an orientation tab, the circuit diagram, as specified (see 3.1),

shall be orientated so that when the relay is held with the circuit diagram right side up as shown (see 3.1), and rotated

away from the viewer about a horizontal axis through the diagram until the header terminals face the viewer, then

each terminal shall be in the location shown in the circuit diagram.

3.5.6 Mounting means (see 3.1).

3.5.6.1 Bracket. Mounting brackets shall be an integral part of the relay, securely attached thereto in a manner to

prevent any movement between the relay and the mounting bracket.

3.5.7 Terminals (see 3.1). Terminals shall be as specified herein. Manufacturer may supply hot solder dipped

terminals provided that the hot solder dipping process has been approved by the qualifying activity and when

specified on the individual purchase order (see 6.2.1a). Solder dipped terminals may be .002 inch (0.051 mm) larger

than the maximum dimension specified (see 3.1).

3.5.7.1 Solder-lug terminals. Solder-lug terminals shall be designed to accommodate two conductors, each rated

to carry the maximum rated current of the contact or coil terminated.

3.5.7.2 Wire leads. Wire leads shall be as specified (see 3.1). Optional, shortened wire leads may be supplied

when specified on the individual purchase order (see 3.1 and 6.2.1b).

3.5.7.2.1 Wire leads, solder pin (SP). Solder pin wire leads shall be as specified (see 3.1).

3.5.7.3 Plug-in termination. Plug-in terminations shall conform to the arrangements or dimensions as specified

(see 3.1). The mounting arrangement of the relay shall be so designed that the entire weight of the relay will be

suspended and the stability of its mounting will be provided by an auxiliary mounting means other than the electrical

terminals of a socket (see 3.1). Plug-in pin terminals shall provide the operational, environmental, and interface

characteristics to provide a reliable interconnect to gold-plated contacts. One system for gold plating that may be

used is ASTM B488, type 3, class 1.25, knoop hardness 130 to 240, with nickel underplate 50 to 150 microinches

thick. The gold plating system shall enable the product to meet the performance requirements of this specification

and shall be approved by the qualifying activity.