By definition a circuit breaker is an electrical safety device, a switch that automatically interrupts the current of an overloaded electric circuit, ground faults, or short circuits. Circuit breakers "trip", shut off, current flow after protective relays detect a fault. Unlike fuses that were used previously, circuit breakers are not usually damaged so they can be reset as opposed to being replaced. Circuit breakers are used in residential and in industrial applications.
There are 5 basic components used in every circuit breaker:
- Tripping or Protective Mechanism – Also known as the trip unit, this triggers the operating mechanism once an electrical fault happens.
- Operating Mechanism – Opens or shuts the breaker to fulfill its protective role.
- Molded Frame – Outer protective and supportive case of most breakers. It shelters the other component of the breaker providing insulation.
- Arc Chutes – Located near the contacts, chutes prevent damage and mostly heat from intervening with the circuit breaker’s functionality and move apart when a fault occurs.
- Contacts – There are three types of contacts: arcing, auxiliary or main contacts that are used to ensure optimal airflow inside the breaker.
4 categories of circuit breakers:
Molded Case Circuit breakers (MCCB)
15-1200A Tmax XT Tested UL 489 and meets NEMA AB Standards
Residential to Industrial
single, two pole or three pole
Insulated Case Circuit Breakers
Powerbreak II Tested UL 489 and meet NEMA AB Standards
Frame Sizes 800-4000A frames - mains and large
Electrically operated breaker
Commercial to Light Industrial - office buildings, schools, shopping malls
Somewhat maintainable but contacts not replaceable
Air power circuit breakers
Heavy industrial application - can involve switchgear
Optimal reliability - Hospitals, Data Centers
Serviceable in the field
Best choice for heavy switching (Contacts replaceable)
30 Cycle Withstand
Frame sizes 250-6000A built on ANSI rated
True switchgear breakers
Used in industrial environments where maintenance staff and customer needs high reliability
All electronic eKip Touch and eKip - Bluetooth standard
3 and 4 pole versions
Miniature Circuit Breakers (MCB)
Used for low-energy requirements, like home wiring, offices, or small electronic circuits.
MCBs are equipped with two tripping mechanisms: the delayed thermal tripping mechanism for overload protection and the magnetic tripping mechanism for short circuit protection.
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