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

4.8.13 Moisture resistance (see 3.17). Circuit breakers shall be tested in accordance with method 106 of

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

Mounting - Mounted horizontally on a panel.

Initial measurements - Immediately following the initial drying period, resistance or impedance shall be

measured as specified in 4.8.6.

Electrical-load conditions - During the first 2 hours of step 1 and step 4, circuit breakers shall be energized at

rated current and at the applicable frequency (see 3.1).

Steps 7a and 7b are not applicable.

Final measurements - Upon completion of the 10 cycle and while still in the humidity chamber, insulation

resistance and resistance or impedance shall be measured as specified in 4.8.4 and 4.8.6, respectively.

After the 24-hour drying period, insulation resistance shall again be measured as specified in 4.8.4.

Examination after test - Examine for evidence of breaking, cracking, spalling or loosening of terminals.

Tests after moisture resistance test - Circuit breakers shall be subjected to the following tests:

(1) Dielectric withstanding voltage (see 4.8.3).

(2) Calibration (see 4.8.5.2) (except that tests at 400 percent, 600 percent, and 800 percent at rated current

shall not be performed).

4.8.14 Thermal shock (see 3.18). Circuit breakers shall be tested in accordance with method 107 of

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

Mounting - Normal mounting means with at least 1 inch of free air space around each circuit breaker.

Test condition - A.

Examination after cycling - Circuit breakers shall be examined for evidence of mechanical damage.

4.8.15 Shock (see 3.19). Circuit breakers shall be tested in accordance with method 213 of MIL-STD-202. The

following details shall apply:

Mounting method - Normal mounting means.

Test condition - I (unless otherwise specified (see 3.1)).

Electrical-load conditions and measurements - Of the three shocks in each direction required, two shocks

shall be performed with the circuit breaker energized at 100 percent rated current dc (see 3.1), except that

for the directions with the operating lever pivot up (table mount) and the operating lever pivot down (ceiling

mount), no voltage or current shall be applied. Each energized shock shall be monitored to determine

opening of the main and, when applicable, auxiliary contacts. The remaining shock in each direction shall

be performed with the circuit breaker contacts open and unenergized and shall be monitored to determine

closing of the main and, when applicable, of the open auxiliary contacts.

Examination after shock - Circuit breakers shall be examined for evidence of mechanical and electrical

damage.

4.8.16 Trip-free calibration (see 3.20). The circuit breaker actuator shall be physically held in the closed position

and the breaker subjected to the calibration tests in accordance with 3.9 and 4.8.5.2.