MIL-PRF-55629 Circuit Breakers, Magnetic, Unsealed Or Panel Seal, Trip-Free, General Specification ForThis specification covers the requirements and test procedures for single and multipole, trip-free, unsealed, magnetic circuit breakers with current ratings of 0.2 amperes to 100 amperes inclusive, up to and including 240 volts, 400 Hertz, 480 volts, 60 Hertz alternating current \(ac\) and 125 volts direct current \(dc\), \(see 6.1\). These circuit breakers may also include auxiliary contacts \(see 6.6.1\) for monitoring circuits. A voltage sensitive pole is also available in a four pole device. Panel seal mounts are available in 0.2 amperes through 50 amperes. Designers are WARNED 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-55629E

4.8.17 Salt atmoshere (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 - Applicable 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 - Circuit breakers shall be subjected to the following tests:

(1) Dielectric withstanding voltage (see 4.8.3).

(2) Calibration at 200 percent rated current (see 4.8.5.2).

4.8.18 Temperature rise (see 3.22). One hundred percent rated current (see 3.1) shall be applied to circuit

breakers for 1 hour. Circuit breakers shall not trip and the temperature rise of the terminals shall be determined.

4.8.19 Interrupting capacity (see 3.23). Circuit breakers shall be connected to the power source with leads

consisting of insulated wires of the size corresponding to the current rating of the circuit breaker; leads are not to be

more than 4 feet in length. The applicable rupture current specified (see 3.1) at the corresponding open-circuit

voltage and frequency specified shall be measured at the power source with the circuit breaker and its test leads

replaced by temporary connections having negligible impedance compared to the test circuit. The test leads and

terminals shall be as specified on figure 1.

For ac operation, unless otherwise specified (see 3.1), the circuit breakers shall be tested with essentially a resistive

load. Single pole breakers shall be subjected to three operations (duty cycle) as shown on figure 3. The operation

for multipole circuit breakers shall follow the pattern of operation as shown for two pole and three pole circuit breakers

on figure 4 and figure 5, respectively.

For dc operation, the circuit breakers shall be tested with direct current using a test circuit having a resistive load.

The circuit and operations (duty cycle) of the tests shall be as shown on figure 6, figure 7, and figure 8, respectively.

During interrupting capacity tests, after each operation, the open-circuit voltage specified shall be maintained across

the breaker for a minimum of 5 seconds. There shall be sufficient time between each operation (not less than 10

minutes) to permit proper cooling of the circuit breaker. Circuit breakers that are not capable of being mechanically

reset within 10 minutes shall be rejected. The 30 ampere fuse connected to the mounting plate shall not be ruptured

during the tests. When applicable (see 3.1), a suitable method shall be employed to test the auxiliary contacts

(see 3.5.8.2). The circuit breakers shall be observed for automatic tripping and satisfactory operation of the auxiliary

contacts. Following the last operation (of the duty cycle) circuit breakers shall be subjected to the following tests:

Dielectric withstanding voltage (see 4.8.3).

Calibration at 200 percent rated current (see 4.8.5.2).

Resistance or impedance, main contacts only (see 4.8.6).