Circuit Breakers, Get what you need

Siemens, Westinghouse, Square D - Obsolete Circuit Breakers,

Circuit Breakers - New & Obsolete
Molded case circuit breakers, insulated case, & air breakers
Electrical Power Transformers
Dry type transformers, pad mount, & substation transformers
Panel boards, Switchboards & Switchgear

New and reconditioned circuit breakers, electrical distribution and control equipment. We specialize in hard-to-find circuit breakers, including obsolete circuit breakers. From Siemens breakers to Cutler Hammer, FPE, General Electric and ITE to a wide variety of Square D breakers and even a large selection of rare or uncommon items, such as Westinghouse breakers and hard-to-find circuit breakers.
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Circuit Breakers, we know all about it.
          The circuit breaker must detect an over-current condition and this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip solenoid that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source.
               Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some mechanically-stored energy (using something such as springs or compressed air) contained within the breaker is used to separate the contacts, although some of the energy required may be obtained from the fault current itself. Small circuit breakers may be manually operated; larger units have solenoids to trip the mechanism, and electric motors to restore energy to the springs.
             The circuit breaker contacts must carry the load current without excessive heating, and must also withstand the heat of the arc produced when interrupting the circuit. Contacts are made of copper or copper alloys, silver alloys, and other materials. Service life of the contacts is limited by the erosion due to interrupting the arc. Mechanical circuit breakers are usually discarded when the contacts are worn, but power circuit breakers and high-voltage circuit breakers have replaceable contacts. When a current is interrupted, an arc is generated. This arc must be contained, cooled, and extinguished in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit. Different circuit breakers use vacuum, air, insulating gas, or oil as the medium in which the arc forms.
                All circuit breakers have common features in their operation. although details vary substantially depending on the voltage class, current rating and type of the circuit breaker.