Introduction to Circuit Breakers, Overload Protection

Basic Circuit Breaker Types, How they Work

Circuit breakers interrupt electrical circuits when overloaded, tripping the breaker for circuit protection from short circuits. If the power overload and tripping persists, circuit breakers need repair, replacement or reconditioning. Industrial circuit breaker types are classified by voltage, construction and current interrupting type.

Circuit Breaker Types

Instantaneous Magnetic: These Trip-Only Circuit Breakers give short circuit protection without overload protection. Instantaneous Magnetic Circuit Breakers are used in motor control where the overload relay provides circuit protection.

Industrial Circuit Breaker Types
Industrial circuit breaker types can be separated by voltage, amperage, among other attributes offering circuit overload protection.

Thermal-Magnetic: A trip unit detects heat to sense overload and magnetic pull caused by current. Thermal Magnetic circuit breakers trip instantaneously during short circuit.

Magnetic Industrial: An electromagnetic (solenoid) pulls as current builds. When current increases beyond breaker capacity, a latch releases and contacts open disruption current.

Molded Case Breakers: Same as thermal-magnetic circuit breakers with a set instantaneous function allowing tripping and overload protection, with no thermal overload or short circuit protection. An electrical power distribution systems use these large industrial Circuit Breakers for short circuit protection, avoiding extensive damage to expensive power equipment. These current limiting circuit breakers reduce current flow in the faulty circuit.

Solid State: Similar to Thermal Magnetic Breakers, however trip units differ. Solid-State trips are programmable for sustained reliability and have a microprocessor. Current sensors connected to the trip unit monitor load current. The trip unit continuously compares current to trip unit settings, and when exceeds the preset, tripping triggers a magnetic latch opening the contacts for overload protection.

Contact Select Equipment Company power distribution specialists at (888) 459-5191 or sales@selectequipment for support in choosing Circuit Breakers suitable for your project.

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