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    14 Jun, 2022
    Posted by elcb_admin
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    What is the DC Circuit Breaker?

    DC circuit breakers refer to circuit breakers used in DC power distribution systems from overcurrent and potential hazards. They perform the following functions:

    Interrupt the flow of current when it exceeds a predefined threshold.

    Protect electrical components from damage caused by excessive current.

    Prevent electrical fires and other safety hazards that can result from overcurrent conditions.

    Generally applicable to solar photovoltaic power generation and power distribution systems, battery energy storage systems, new energy vehicle DC charging systems, etc.

    A system in which the input power supply terminal of the circuit breaker is DC current.

    General DC circuit breakers include DC MCB (Miniature Circuit Breaker), DC MCCB (DC molded case circuit breaker), and Type B RCD (Residual Current Device).

    The DC Circuit Breakers Working Principle

    1. Current detection
    DC circuit breakers first require a current sensing mechanism to monitor the current levels in the circuit. This is usually achieved through a built-in current sensor, which can be resistive, current transformer (CT) or other type of sensor. When the current exceeds a preset safety threshold, the sensor triggers the circuit breaker’s protection mechanism.

    2. Signal processing
    Once an abnormal current is detected, the sensor sends a signal to the circuit breaker’s control unit. The control unit evaluates this signal and determines whether measures need to be taken to interrupt the circuit. In some advanced DC circuit breakers, this evaluation process may include complex algorithms to distinguish between true faults and temporary current fluctuations.

    3. Circuit breaking action
    If the control unit determines that the circuit needs to be opened, it activates the mechanical or electronic switching portion of the circuit breaker. In a mechanical circuit breaker, this may involve a fast-acting spring mechanism that rapidly separates the circuit breaker’s contacts, interrupting the current flow. In electronic circuit breakers, this may involve semiconductor switching devices such as transistors or thyristors, which can switch states very quickly.

    4. Arc suppression
    During the process of breaking a circuit, arcing may occur as the current attempts to maintain its path. Arcing can generate high temperatures, damage equipment, and possibly cause fires. Therefore, DC circuit breakers often contain arc suppression devices that rapidly cool the arc and dissipate its energy to prevent the arc from causing damage to the circuit breaker itself or connected equipment.

    5. Reset and restore
    Once the circuit is disconnected, the system can be safely inspected and repaired. After the problem is resolved, the circuit breaker can be reset manually or automatically. Some DC circuit breakers have an auto-reset feature that allows them to automatically restore connections after confirming that the circuit is safe. However, for certain types of failures, a manual reset may be required to ensure the safety of the system.

    Types of DC Circuit Breakers

    DC circuit breakers come in various types, each with its unique features and applications:

    1. Thermal-Magnetic Circuit Breakers: These breakers combine a thermal element, which reacts to heat generated by overcurrent, and a magnetic element, which responds to high current levels, to provide protection in a wide range of situations.
    2. Electronic Circuit Breakers: Utilizing electronic components, these breakers can offer faster response times and adjustable settings for overcurrent protection.
    3. Hybrid Circuit Breakers: Combining both mechanical and electronic components, hybrid breakers can provide fast, reliable protection while minimizing the risk of nuisance tripping.
    4. Part 3: The Role of Voltage Meters in DC Systems

    What is DC?

    Diagram of Four Kinds of Electric Currents - Direct, Alternating, Pulsating, Variable
    Source: Wikipedia

    Definition and Characteristics

    Direct current (DC) is a type of electrical current that flows in one constant direction. It is generated by sources such as batteries, solar panels, and fuel cells. Unlike alternating current (AC), which periodically changes direction, DC maintains a consistent flow, making it the preferred choice for many electronic devices and systems.

    Advantages of DC

    Direct current offers several advantages over alternating current:

    Efficiency: DC systems typically experience fewer energy losses compared to AC systems.

    Compatibility: Many electronic devices, such as computers and smartphones, require DC power to operate.

    Simplicity: DC systems can be easier to design and maintain due to their constant voltage and current levels.

    DC Circuit Breaker MCB (DC Miniature circuit breaker)

    DC miniature circuit breaker MCB is specially designed for direct current (DC) circuit applications and is used for over-current and short-circuit protection in electrical appliances or electrical equipment.

    DC MCB and the AC MCB are same functions. but, the usage scenarios of AC MCB and DC MCB are different.

    DC MCB mostly uses for direct current (DC) systems application, such as new energy, solar photovoltaic (PV) and Solar cell energy storage system. The voltage state of DC MCB is generally DC 12V-1500V.

    The difference between AC MCB and DC MCB in physical parameters on products.

    The AC MCB are marked as LOAD and LINE on products, and the DC circuit breaker symbol marked as positive (+), negative (-) signs and the direction of the current on products.

    TOMD6-63DC Direct Current Circuit Breaker
    DC CIRCUIT BREAKER-1

    DC MCCB (DC Molded Case Circuit Breaker)

    DC MCCB (DC Molded Case Circuit Breaker) are ideal for energy storage, transportation, and industrial DC circuits.

    DC molded case circuit breaker with same functions of AC MCCB, it has overload and short-circuit protection functions for high-current power distribution systems.

    They are also used in ungrounded battery supply circuits for emergency back-up and standby power. Available up to 150A, 750 VDC and up to 2000A, 600 VDC. For DC breakers used in grounded photovoltaic systems in solar installations, application engineering and review ensures protection requirements are met.

    DC MCCB (DC Mold Case Circuit Breaker) is a circuit control protection device for energy storage, transportation and industrial DC circuits. They are also used in ungrounded battery-powered circuits to provide emergency backup power and backup power. TONGOU produce high voltage dc circuit breaker,TONGOU DC MCCB can provide up to 150-800A, 380V-800V DC.

    TOSM8DC-125 125A DC MCCB
    TOSM8DC 125A DC MCCB
    TOSM8DC-125 125A DC MCCB
    TOSM8DC 250A DC MCCB

    Can i use a ac circuit breaker for dc?

    The signal of AC current is constantly changing its value for every second. The circuit breaker arc will be extinguished at 0 volts, and the circuit will be protected from big current.

    But the signal of DC current is not alternating, it works in a constant state, and the voltage value will only change when the circuit is tripped or the circuit is reduced as a certain value.

    Otherwise, the DC circuit will provide a constant voltage value for every second of a minute. Therefore, since there is no 0 volt point in the DC state, it does not suggest that use a AC circuit breaker for the DC state.

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