MIL-DTL-19648 Relays, Time Delay, Thermal, General Specification ForThis specification covers the general requirements for thermal, time delay relays for use in electrical applications. Relays covered by this specification are capable of meeting the electrical and environmental requirements when mounted directly to the structure of aircraft, missile, spacecraft, ship, and other primary vehicles or in ground support and shipboard equipment. Other ratings may be as specified \(see 3.1\).