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 \(see 6.5\).

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11

MIL-PRF-55629E

3.4.2 Fungus resistance. Materials shall be used that are not nutrients for fungus.

3.4.3 Solder and soldering flux. The solder and solder flux shall be of such a quality as to enable the circuit

breaker to meet the performance requirements of this specification.

3.5 Interface and physical dimensions . Circuit breakers shall be of the interface and physical dimensions

specified (see 3.1).

3.5.1 Trip-free feature. Circuit breakers shall be designed so that the circuit cannot be maintained closed by

physically holding the actuator lever in the closed position when any pole is carrying overload currents that would

normally automatically trip the circuit breaker to the open position.

3.5.2 Trip indication. Circuit breakers shall be designed so that the circuit breaker contacts open automatically on

overload, the actuator lever shall indicate the operation by moving to the "off" ("trip") position.

3.5.3 Attitude. Circuit breakers shall be constructed to trip within maximum and minimum limits of the specified trip

times (see 3.1 and 6.6.5), when mounted on a vertical panel (normal mounting means) (see 4.8.5).

3.5.4 Actuator. The actuator shall be as specified (see 3.1). The exposed portion of actuators shall be insulated

from all current-carrying parts. The exposed portion of metal actuators shall have a smooth, nonglare, metallic finish.

Actuators shall not work to an intermediate position, give a false trip indication, or be removable from the circuit

breaker. Multipole circuit breakers having individual pole actuators (see 6.6.3), shall be provided with handle ties for

convenient manual switching, and the circuit breaker shall be such that it will be impossible by any manipulation of

the actuator to close less than the total number of contacts. Actuators of the lever type shall point in the "normally

upward" (top of the circuit breaker) direction when the circuit breaker is in the "closed" ("on") position. Actuators of

the push-pull type shall be in the "closed" ("on") position when the actuator button is pushed in.

3.5.5 Mounting means. Mounting means shall be as specified (see 3.1).

3.5.6 Terminal and mounting hardware (as applicable). Terminal and mounting hardware shall be as specified

(see 3.1). For direct Government procurement, the hardware shall be assembled in proper order, as specified

3.5.7 Threaded parts. Screw threads on external threaded parts used for mounting shall be in accordance with

3.5.8 Terminals.

3.5.8.1 Line and load terminals (see 6.6.2). The main line and load terminals shall be designed and mounted as

specified (see 3.1). For bushing-mounted types of circuit breakers, where a locating keyway is used, load terminals

will be on the side of the keyway and line terminals will be on the side opposite the keyway. Each terminal shall be

capable of carrying rated current and voltage per pole of the circuit breaker.

3.5.8.2 Auxiliary contact terminals. When specified (see 3.1) circuit breakers shall be provided with auxiliary

contacts (see 6.6.1) of the specified switching type, and terminals of the design and location specified (see 3.1).

Contacts and terminals shall be capable of carrying specified loads. Auxiliary contacts shall be of double throw

configuration with permanent designations as follows adjacent to the contact terminals: "NO" for normally open, "NC"

for normally closed, and "C" for common. The auxiliary contacts shall be arranged in a manner to ensure (regardless

of actuating lever or push-button position) that the normally open contacts are closed when the main circuit breaker

contacts are closed, and the normally closed contacts are closed when the main circuit breaker contacts are open.

3.5.8.2.1 Solder terminals. Unless otherwise specified, solder terminals may be of any shape and shall be capable

of being readily soldered. Solder terminals shall not be gold plated.

3.5.9 Reset mechanism. The reset mechanism shall be such that retaining the actuator in the closed position after

automatic tripping occurs shall not adversely affect subsequent performance of the circuit breaker.

3.5.10 Tamper-proof calibration. Circuit breakers shall be secured with a tamper-proof closure so that the

calibration of the device is kept intact and cannot be disturbed without it being dismantled.

3.5.11 Solder. Solder shall not be used primarily for obtaining mechanical strength. Electrical connections shall

be mechanically secure before soldering and electrically continuous after soldering.

3.5.12 Voltage rating. Voltage rating shall be as specified (see 3.1).