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

4.6.18 Overload cycling (see 3.23). Each switch shall be tested for overload cycling using the same voltage,

electrical frequency, and the same pair(s) of contacts that will subsequently be used for the electrical endurance test.

The switches shall close and open the overload current of a resistive circuit equal to 150 percent of the resistive load

rating and the particular voltage and electrical frequency. The cycling rate shall be less than 6 cycles of operation per

minute. Fifty cycles of operation shall be performed. The duty cycle shall be approximately 50 percent on, 50 percent

off.

4.6.19 Endurance (see 3.24). Switches shall be subjected to the specified number of cycles of make-and-break

operations at a cycling rate of 6 cycles per minute maximum at the rated loads (see 3.1 and 6.2.2).

4.6.20 Salt spray (corrosion) (see 3.25). Switches and their mounting hardware and brackets (if applicable) shall

be tested in accordance with method 101 of MIL-STD-202. The following details shall apply:

(a)

Applicable salt solution - 5 percent.

(b)

Test condition - B.

(c)

Measurements after exposure - Following the drying period, the switches shall meet the requirements

specified in 3.25. Mounting hardware shall be removed at the end of the test.

4.6.21 Sand and dust (see 3.26) (when specified, see 3.1 and 6.2.2). Switches shall be tested in accordance with

method 110 of MIL-STD-202. This test shall be performed with the pressure port suitably capped or plugged. The

following details shall apply:

(a)

Test condition - B.

Measurements - Switches shall be tested in accordance with 4.6.3.

(b)

4.6.22 Explosion (see 3.27) (when specified, see 3.1 and 6.2.2). Switches shall be tested in accordance with

method 109 of MIL-STD-202. The following detail shall apply:

(a)

Mechanical and electrical load - Switches shall be operated at their maximum rated dc inductive current

(see 3.1 and 6.2.2).

4.6.23 Low level (see 3.30) (when specified, see 3.1). Switches shall be tested for the number of cycles specified

(see 3.1) as follows:

(a)

Contact load - Each switch contact shall make, carry, and break a resistive load of 10 milliamperes

maximum at an open circuit voltage of 30 millivolts maximum dc or peak ac. Both normally open and

normally closed contacts shall be loaded. Contacts shall be connected to individual loads.

(b)

Operate cycles - Rate not to exceed 6 cycles per minute.

(c)

Monitoring circuit - The monitoring equipment shall provide a record of the number of cycles and shall

record failures, or discontinue the test, if a failure occurs. During each closure, the contact potential shall be

monitored for at least 50 percent of the time the contacts are closed.

4.6.24 Minimum current (intermediate current) (see 3.31) (when specified, see 3.1). Switches shall be subjected

to the number of cycles of make-and-break operations specified (see 3.1), in a circuit having a 27 +3 and -0 volt dc

source and a load consisting of the coil of relay, part number M5757/10-033, or equivalent. The cycling rate shall not

exceed 6 cycles per minute, and switches shall be monitored for make-and-break operations.

4.6.25 Resistance to solvents (see 3.32). Switches shall be tested in accordance with method 215 of

MIL-STD-202. The following details and exception shall apply:

(a) Portion to be brushed - All marking areas.

(b) Number of specimen to be tested - Three.