Molded Case Circuit Breakers

Features

General Electric Bolt-On Circuit Breakers

• These General Electric TEYH Series MCCBs have a thermal-magnetic, non-interchangeable trip unit to protect from severe power surges while avoiding tripping on mild overloads.
• They also have a bolt-on mounting facility for convenience and compatibility with lug-lug / unit-mount applications.
• These UL-listed breakers are available in single, two and three-pole configurations and accommodate universal 10 to 4 AWG size wires.

Square D PowerPacT Circuit Breakers

• These Square D MCCBs have a new front-facing and semi-transparent cover for easy access to accessories.
• They have current ratings ranging from 15 to 125A and offer a maximum breaking capacity of 65kA at 480VAC.
• These RoHS and REACH-compliant breakers feature dual-break rotating contacts that reduce peak current during a short circuit fault.

Eaton HKD Series Circuit Breakers

• Eaton HKD Series circuit breakers protect against overload and short circuit conditions in 480Y / 277V (three-phase, four-wire) distribution panels.
• They have 2-pole construction and can serve two separate circuits or a complete single circuit when short-circuited.

Working Mechanism

Molded case circuit breaker's working mechanism includes following steps:

• In the normal state, molded case circuit breakers allow electrical current to flow through the circuit uninterrupted.
• When an overcurrent condition occurs, the MCCB's internal sensors detect the excess current flowing through the circuit.
• They have two main trip mechanisms: electromagnetic trip and thermal trip.
• The electromagnetic trip detects sudden, high-current surges, similar to short circuits, and quickly opens the circuit to cut power.
• The thermal trip reacts to prolonged overloads by heating up, causing the MCCB to trip and disconnect the circuit.
• Once the trip mechanism is activated, it triggers a mechanical release within the circuit breaker.
• Hence, the breaker's contacts move quickly to the open position.
• When the contacts are open, the MCCB interrupts the electrical flow, effectively cutting off power to the circuit.
• The circuit remains in this disconnected state until manually reset by the user.