MIL-PRF-24236 Switches, Thermostatic, \(Metallic And Bimetallic\), General Specification ForThis specification covers the general requirements for metallic-element actuated, thermostatic switches intended primarily for use in electrical and electronic equipment, in alternating current \(ac\) and direct current \(dc\) applications, where temperature protection, overheat detection, or accurate temperature control is required. The operating temperatures and operating temperature ranges of switches are covered by this specification \(see 3.1 and 6.2.2\).

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MIL-PRF-24236D

3.12 Seal (as applicable, see 3.1 and 6.2.2).

3.12.1 Hermetic. When switches are tested as specified in 4.6.7.1, the leakage rate shall not exceed 1 x 10-8

standard atmospheric cubic centimeters per second (atm cc/sec).

3.12.2 Watertight. When switches are tested as specified in 4.6.7.2, there shall be no leakage as evidenced by a

continuous stream of bubbles.

3.13 Dielectric withstanding voltage. Unless otherwise specified (see 3.1 and 6.2.2), when switches are tested as

specified in 4.6.8, there shall be no flashover, arcing, or current flow in excess of 500 microamperes.

3.14 Insulation resistance. When measured as specified in 4.6.9, the insulation resistance between all insulated

terminals and enclosures shall be not less than 500 megohms.

3.15 Contact resistance. Unless otherwise specified (see 3.1 and 6.2.2), when measured as specified in 4.6.10,

the initial contact resistance shall not exceed 25 milliohms. Following the endurance test, contact resistance shall not

exceed 50 milliohms.

3.16 Thermal shock. When switches are tested as specified in 4.6.11, there shall be no mechanical or electrical

damage. The temperature settings shall be within the opening and closing temperature tolerances as specified (see

3.17 Terminal strength. When switches are tested as specified in 4.6.12, the terminals shall not break, loosen,

crack, or affect the operation of the switch.

3.18 Moisture resistance. When switches are tested as specified in 4.6.13, the insulation resistance, immediately

after conclusion of the test, shall be greater than 2 megohms at 500 Vdc. At the end of the drying period, the

insulation resistance shall be as specified in 3.14. At the conclusion of the test, there shall be no evidence of

corrosion or mechanical damage.

3.19 Flame response (when specified, see 3.1). When switches are tested as specified in 4.6.14, the time required

for the switch to operate shall not exceed 5 seconds.

3.20 Short circuit. When switches are tested as specified in 4.6.15, there shall be no welding or sticking of

contacts, or damage. Switches shall be mechanically and electrically operative at the end of the test.

3.21 Vibration. Unless otherwise specified (see 3.1, 6.2.2, and 3.5.3), when switches are tested as specified in

4.6.16, closing of open contacts and opening of closed contacts shall not exceed 10 microseconds.

3.22 Shock. Unless otherwise specified (see 3.1, 6.2.2, and 3.5.3), when switches are tested as specified in

4.6.17, there shall be no change in operation or evidence of broken, deformed, displaced, or loose parts.

3.22.1 Method I (shock, specified pulse) (applicable to classes 1, 3, 4, 5, and 6) (see 3.1 and 6.2.2). When

switches are tested as specified in 4.6.17.1, closing of open contacts and chatter of closed contacts shall not exceed

10 microseconds, unless otherwise specified (see 3.1 and 6.2.2).

3.22.2 Method II (high-impact shock) (applicable to class 2 only, see 3.1 and 6.2.2). When switches are tested as

specified in 4.6.17.2, closing of open contacts and chatter of closed contacts shall not exceed 5 milliseconds, unless

otherwise specified (see 3.1 and 6.2.2).

3.23 Overload cycling. When switches are tested as specified in 4.6.18, there shall be no mechanical or electrical

failure.

3.24 Endurance. When tested as specified in 4.6.19, switches shall remain electrically operative.