MIL-PRF-39019 Circuit Breakers, Magnetic, Low-Power Sealed, Trip-Free General Specification ForThis specification covers the requirements and test procedures for single and multipole, trip-free, sealed, low-power, magnetic circuit breakers with current ratings of 0.050 amperes to 20.0 amperes inclusive, up to and including 240 volts, 60 hertz \(Hz\) and 400 Hz alternating current \(ac\), and 50 volts direct current \(dc\) \(see 6.1 and 6.7\). These circuit breakers may also include auxiliary contacts \(see 6.6.1\) and terminals for monitoring circuits. Designers are CAUTIONED that these circuit breakers may contain a pure tin finish on some of the component parts \(see 6.5\).

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MIL-PRF-39019F

4.8.18 Salt atmosphere (corrosion) (see 3.21). Circuit breakers shall be tested in accordance with method 101 of

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

Test condition: B.

Examination after exposure: The mounting hardware shall be removed at the conclusion of the test. Circuit

breakers shall be examined for corrosion or evidence of mechanical and electrical damage.

Tests after salt atmosphere test:

(1)

Dielectric withstanding voltage (see 4.8.3).

(2)

Calibration (see 4.8.6.2).

Seal (4.8.8).

(3)

(4)

Panel seal (see 4.8.9).

4.8.19 Barometric pressure (reduced) (see 3.22). Circuit breakers shall be tested in accordance with method 105

of MIL-STD-202. The following details shall apply:

Test condition: B.

Tests during subjection to reduced pressure: Dielectric withstanding voltage shall be performed as specified in

4.8.3, except the magnitude of test voltage shall be 500 volts (rms) for all points of application.

Examination after tests: As specified in 4.8.3e.

4.8.20 Temperature rise (see 3.23). Circuit breakers shall be connected with not less than 4 feet of No. 16 wire for

ratings up to 5 amperes, No. 14 for ratings of 5 amperes through 15 amperes, and No. 12 for ratings above 15

amperes. Connections to the circuit breaker terminals shall be soldered. The temperature rise of the terminals shall

be determined by the use of a thermocouple with a .0100 inch (0.254 mm) diameter (No. 30 AWG), or smaller wire.

The thermocouple shall be cemented to the terminals, using minimum quantity of cement. One hundred percent

rated current shall be applied to circuit breakers for 1 hour. Circuit breakers shall not trip and the terminal

temperature rise shall not exceed the values specified in 3.23.

4.8.21 Interrupting capacity (see 3.24). The sample units shall be operated through interrupting cycles (ac or dc,

as applicable) as specified herein. Circuit breakers shall be connected to the power source so that the applicable

short circuit current specified below, at the corresponding open circuit voltage and frequency specified, is provided at

the circuit breaker terminals. The power factor shall be 75 percent to 80 percent for the 60 Hz test and 30 percent to

80 percent for the 400 Hz test.

500 amperes at 50 V dc �2 V dc.

300 amperes at 240 V ac �5 V ac, 60 Hz or 400 Hz as applicable.