How Many Types Of Molded Case Circuit Breakers Are There?

Molded case circuit breakers can be classified according to the following four factors: tripping method, protection function, application scenario and structural characteristics. Specific types and analyses are as follows:
I. By
Thermal Tripping
How it works: Triggers are a bimetallic strip bent by heat and have a slow response time (seconds).
Purpose: To provide overload protection for common loads (such as lighting circuits) insensitive to transient current fluctuations.
Features: Simple structure, low cost, but cannot withstand short circuit shock.
Magnetic Tripping
Principle: Electromagnetic coil induces the magnetic field produced by short circuit current, realizing millisecond-level rapid tripping.
Purpose: To provide short circuit protection in case of possible excitation inrush, such as motor startup.
Features: Very fast response time, but doesnot discriminate between overload and short circuit and requires to be used with other types.
Combined Thermal-Magnetic Tripping
Principle: The combination of thermal tripping (overload protection) and magnetic tripping (short-circuit protection) provides dual protection.
Purpose: Generic distribution system for most industrial and commercial applications. Characteristics: high value for money, is currently the most widely used type.
Types of e-tourism
Principle: Current is monitored by electronic circuit, the parameters (such as tripping current, time curve, etc.) are adjustable, and the accuracy is high.
Applicable Scenarios: Data centers, sophisticated devices, and other applications requiring complex protection.
Features: Flexible functionality but expensive, requiring professional debugging.
ii. By Protective Function
Type of two-tier protection
Function: delay overload protection + instantaneous short circuit protection.
Solution: The distribution system is simple and the low selectivity requirements.
Features: Simple structure, low cost, but short protection time, easy to cause over-tripping.
Level 3 protection
Function: long timedelay overload protection + short timedelay short circuit protection + instantaneous short circuit protection.
Applicable Scenarios: Distribution systems (such as industrial motor circuits) that require selective coordination between upper and lower levels.
Features: Short time delay can prevent false tripping of the upper circuit breaker in case of short circuit and improve the reliability of the system.
Type of four-stage protection
Function: add grounding ground fault protection on the basis of three layers of protection. Applicable Scenario: Places with high requirements for personal safety (e.g. data centers, hospitals, etc.).
Features: Overload, short circuit, ground faults coverage, but relatively high cost.
III. By Application Scenario
Electricity distribution protection
Function: Distribution, preventing overload, short circuit, low voltage, etc.
Typical Model: Schneider NSX Series, Chint NM Series.
Features: Rated current is selected based on 1.2 times the total load of the building to meet distribution needs of the building.
Motor protection
Features: Can be configured to delay travel to prevent jet water when motor startup.
Typical: ABB Tmax Series.
Features: high short-term withstand current (ICW) capability to prevent motor stall interference.
Special environmental protection
Function: Suitable for bad environment (such as humidity, salt mist, vibration, etc.).
Typical Type: Marine Molded Case Circuit Breakers, Nuclear Power Industry Circuit Breakers.
Features: Sealed design and corrosion-resistant materials to ensure reliable operation under extreme conditions.
IV. INTRODUCTION Introduction by Structural Characteristics
Fixed
Structure: Contact points, arc extinguishers and other components are fixed and cannot be removed.
Applicable Applications: High current specification (above 630A), stable installation required.
Features: Excellent heat dissipation but limited flexibility.
Rails
Structure: Installed on standard guide rails, modular design, easy to expand and replace.
Applicable Applications home, office and other limited space distribution box.
Features: Compact installation, but care must be taken to touch the seal to prevent loosening.
Double disruption
Structure: The moving contacts are designed with rotating double breakpoints, each of which consists of two contact points.
Typical Model: SDCM3 Series.
Features: Significant improvement in fragmentation (e.g., max Icu = Ics = 150kA at AC400V), excellent flow limiting performance.