PUGAO (Plannter Electric) is a professional manufacturer of Molded Case Circuit Breakers based in China. With extensive experience in the field, we offer customized solutions to meet your specific needs. If you require more than just this specific type of equipment—and are instead seeking a comprehensive, one-stop solution for low-voltage and high-voltage electrical systems—we invite you to contact us.
What Does an MCCB Protect?
Molded Case Circuit Breakers (MCCBs) are primarily utilized in low-voltage power distribution systems. Their core function is to safeguard cables, generators, motors, and transformers against damage caused by the following three types of faults:
Overload Protection: When the current exceeds its rated value—though without reaching short-circuit levels—the circuit breaker employs the principle of thermal deflection (using a bimetallic strip) to interrupt the power supply with a time delay, thereby preventing wiring from overheating and catching fire.
Short-Circuit Protection: In the event of a sudden, massive surge in current, the circuit breaker utilizes an electromagnet to trigger an instantaneous trip, forcibly disconnecting the circuit within milliseconds to prevent equipment from exploding.
Undervoltage Protection (Optional): Automatically trips the circuit when the voltage drops below a safe threshold, thereby protecting sensitive and precision equipment.
Product Type: Thermal-Magnetic vs. Electronic
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Features
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Thermal-Magnetic Type
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Electronic Type
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Core Components
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Bimetallic Strip + Electromagnet (Purely Mechanical)
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Microprocessor + Current Transformer (Smart Chip)
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Protection Functions
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Basic Protection (Long-Delay Overload + Instantaneous Short-Circuit)
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Comprehensive Protection (Overload + Short-Circuit Time Delay + Short-Circuit Instantaneous + Ground Fault)
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Regulation Capabilities
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Fixed or Limited Adjustment Range
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High-Precision Adjustable Settings (Both Current and Time are Programmable)
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Key Advantages
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Simple Structure, Durable, Low Cost
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Intelligent, Selective Protection (Prevents Nuisance Tripping)
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Applicable Scenarios
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General Power Distribution, Motor Protection
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Critical Power Distribution, Generator Protection, and Zone Selective Interlocking
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Key Parameters and Selection Criteria
To select the appropriate molded case circuit breaker (MCCB), PUGAO recommends that you focus on the following criteria; alternatively, you may provide us with your specific project details, and we will develop a customized solution for you:
1. Frame Size Rated Current
This refers to the maximum trip unit capacity that can be accommodated within a specific housing size. For example, a circuit breaker with a 250A frame size can be configured to 100A, 160A, or 250A specifications simply by replacing its internal components.
2. Rated Current
The maximum current that the circuit breaker is permitted to carry continuously under long-term operating conditions. Common specifications include 100A, 160A, 200A, 250A, 400A, 630A, 800A, and others.
3. Breaking Capacity
This metric measures the circuit breaker's ability to withstand electrical stress. It refers to the maximum short-circuit current that the device can safely interrupt.
Type C: Economy Class (approx. 25kA–35kA).
Type S / Type F: Standard Class (approx. 50kA).
Type H / Type L: High Breaking Capacity Class (up to 85kA, or even exceeding 100kA).
4. Number of Poles
3P: Used for three-phase power systems.
4P: Used for three-phase, four-wire systems; commonly utilized in dual power source switching systems.
The Core Differences Between MCCBs and MCBs
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Features
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MCB
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MCCB
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Rated Current
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Typically up to 125A.
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Extremely wide range, spanning from 16A to 1600A (or even higher).
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Breaking Capacity
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Typically 6kA – 10kA.
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Exceptionally high capacity, reaching upwards of 25kA to 100kA.
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Adjustability
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Non-adjustable (parameters fixed at the factory).
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Adjustable (current trip settings are typically adjustable).
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Applications
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Final distribution (homes, offices).
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Suitable for branch circuit distribution or main power distribution (factories, large shopping malls, data centers).
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Accessory Installation
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Infrequent.
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Supports a comprehensive range of accessories (shunt trips, alarm contacts, auxiliary contacts).
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Core Application Scenarios
Molded Case Circuit Breakers (MCCBs) are widely utilized across various sectors, including power distribution, construction, and industry:
Branch Circuit Protection in Distribution Systems: In factory distribution cabinets, Air Circuit Breakers (ACBs) typically serve as the main incoming switch, while MCCBs are employed to protect the downstream branch circuits.
Motor Protection: Specifically designed to provide protection tailored to the unique characteristics of electric motors—namely, their high starting currents and susceptibility to damage from phase loss.
Main Incoming Lines for Large Buildings: In commercial complexes and office buildings, MCCBs with ratings ranging from 400A to 800A are commonly used as the main switches within floor-level distribution panels.
Generator Output Protection: Safeguarding expensive diesel generators against the severe shock caused by load short circuits.
Why Choose Our Products?
Arc Suppression Design: MCCBs are required to handle massive fault currents; the arc-extinguishing chambers in PUGAO products feature thickened grids capable of instantly extinguishing powerful electric arcs.
Thermosetting Enclosure: The enclosure is constructed from high-strength thermosetting plastic, enabling it to withstand immense internal pressure and heat—without shattering—during a short-circuit fault.
Silver-Based Contacts: Large-surface-area silver alloy contacts ensure low contact resistance and an exceptionally long mechanical service life.
