Paidong Industrial Zone Qiligang,Yueqing City,Zhejiang province,China.
Paidong Industrial Zone Qiligang,Yueqing City,Zhejiang province,China.
Shopping Cart
  • No products in the cart.

    What is a circuit breaker?

    Its basic function is to interrupt current after protective mechanism detect a fault

    A circuit breaker has a function to protect an electrical circuit from damage caused by overcurrent, overload, leakage current or short circuit, it is an automatically operated electrical switch designed. Its basic function is to interrupt current after protective mechanism detect a fault. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.

    Circuit breakers are made in multiple sizes, like the small devices that protect low voltage circuits or individual household appliance, and the large switchgear designed to protect high voltage circuits support an entire city.

    How many types of circuit breaker?

    A circuit breaker is an indispensable safety device in electrical equipment, and a qualified circuit breaker has a long service life. For different application environments and actual use requirements, there are many types of circuit breakers to choose from. There are ACB, VCB, etc. for high-voltage alternating current, MCB, MCCB, RCCB, RCBO, AFCI, etc. for low-voltage alternating current, and for direct current, there are also high-voltage DC circuit breakers.

    How circuit breaker works?

    A circuit breaker is a mechanical switching device. When the current on the circuit exceeds the rated current of the circuit breaker due to some conditions such as a short circuit or overload, the circuit breaker will trip to disconnect the circuit, thereby protecting the equipment on the circuit. The mechanical handle of the circuit breaker can also be opened and closed manually, which is convenient for daily maintenance and other work.

    The rated current of a circuit breaker refers to the highest current value that the circuit breaker can continuously carry when other conditions (temperature, etc.) remain within the specified range.

    TOMC7-63 40A 2P DC Circuit Breaker MCB

    Miniature circuit breaker(MCB) ensure electrical safety in homes offices and other buildings as well as for industrial applications by protecting electrical installations against overloads and short circuits.
    Once a fault is detected, the miniature circuit breaker automatically switches off the electrical circuit to prevent damage to wires and to avoid the risk of fire.

    Molded case circuit breaker(MCCB) for short, has the functions of short circuit protection, overload protection, and switching circuit, generally, with leakage protection, we call it a molded case leakage circuit breaker.
    It is mainly used for terminal power distribution and can carry load directly. The maximum rated current shall not exceed 1600A. Its function is relatively simple, with thermal-magnetic, electromagnetic tripping, Undervoltage tripping, fault tripping, alarm and other functions, with several groups of auxiliary contacts.

    A residual current device(RCD), residual current circuit breaker(RCCB), or earth leakage circuit breaker(ELCB), is a safe life-saving device that is designed to prevent humans from getting an ongoing fatal electric shock if you touch something live, such as a bare wire.
    Tongou always adheres to the principle of “quality first”, adheres to management informatization, and production automation continuously improves production process quality and production management level.

    Air circuit breaker is a circuit protection device for high current, commonly used in large circuit distribution box system, it can prevent overload, short circuit, ground fault, leakage protection, remote control and other integrated circuit breakers. Therefore, its operation may be efficient and reliable in accordance with the IEC 60947-2 series of standards.

    1. What is the Overcurrent, Short Circuit, Overload and Leakage Current?


    Overcurrent as any current that exceeds the rated current of the device for which the conductor is carrying capacity. Overcurrent is the result of overload, short circuit, arc or ground fault. The effects of overcurrent include fire, conductor insulation damage and equipment damage.

    Short Circuit

    A short circuit is an overcurrent that greatly exceeds the normal full load current of the circuit. In addition, a short circuit leaves the normal current carrying path of the circuit and takes a short-circuit around the load and back to the power source. A short circuit is an overcurrent, but not an overload.


    According to IEC, overload means that the operation of the equipment exceeds the normal, full-load rating, or the operation of the conductor exceeds the rated current carrying capacity, which will cause damage or dangerous overheating when it lasts for a long enough time. An overload is not a short circuit, ground or arc fault.

    Leakage Current

    Leakage current is the current that flows from the AC or DC circuit in the device to the distribution box or ground, and it can come from input or output. If the equipment is not properly grounded, current will flow through other paths such as the human body. This can also happen if the grounding efficiency is inefficient or interrupted intentionally or unintentionally, If the value of the leakage reaches a certain level, It may cause electric shock, resulting in personal injury or even death.

    2. Circuit Breaker Components

    After having a certain understanding of the function of the circuit breaker, we can understand the structure of the circuit breaker to know how it works.

    Although medium and low voltage circuit breakers have unique designs in terms of current intensity, voltage and application, there are five main components in different types of circuit breakers.

    The four universal circuit breaker components are:

    • 1. Frame – Protect the internal parts of the circuit breaker from external materials
    • 2. Operating mechanism –Provide circuit breaker opening and closing methods
    • 3. Arc extinguisher – The arc is extinguished when the circuit breaker interrupts the fault.
    • 4. Contacts – Allow current to flow through the circuit breaker when closed.


    The circuit breaker frame provides the stiffness and strength required to successfully respond to the breaking process and achieve the required breaking rating. It insulates and isolates current to protect personnel and equipment during use or operation. The frame can be made of metal or plastic molded insulating material.

    The molded case frame is made of a strong insulating material, such as glass polyester or thermoset composite resin (plastic frame). TONGOU Electrical provides miniature circuit breakers, molded case circuit breakers, insulated case circuit breakers and low voltage power circuit breakers in molded case frames.

    Two types of operating mechanism – circuit breaker component

    There are two types of operating mechanisms:

    1. Over toggle mechanism (OTM).
    2. Two-step stored energy.
    TOMC3-63 Miniature Circuit Breaker

    What is an over toggle mechanism (OTM)?

    The function of the Over Toggle Mechanism (OTM) is to provide a means of opening and closing the circuit breaker. When the operating handle is moved toward the ON or OFF position, the springs are compressed. They store the mechanical energy of this movement. At the over the center of toggle point, the springs release that stored energy and push or pull the switch blades closed or open.

    This over toggle mechanism is the quick-open, quick-break type, meaning that the speed of contacts point open or close after the toggle point is independent of the speed of the operator.

    In addition to indicating whether the circuit breaker is ON or OFF, the operating mechanism handle also indicates when the circuit breaker is tripped by moving to an intermediate position between ON and OFF.

    TONGOU’s residential circuit breakers, miniature circuit breakers and molded case circuit breakers use over toggle mechanisms.

    What is a two step stored energy mechanism?

    A two step stored energy mechanism is used when a large amount of energy is required to close the circuit breaker and when it needs to close rapidly. it is is a mechanism for closing a breaker where a spring is charged (first step) and then an action is performed (second step) to close the breaker. there are advantages of this mechanism are fast reclosing and safety.

    Fast reclosing is achieved by storing the charging energy in a separate closing spring. Safety is achieved by providing spring remote charging.

    In addition to indicating whether the circuit breaker is ON or OFF, the operating mechanism handle also indicates when the circuit breaker is tripped by moving to an intermediate position between ON and OFF.

    The two step energy storage process aims to store energy for the closing spring and release the energy to close the circuit breaker. It uses separate opening and closing springs.

    This is important because it allows the closing spring to be charged independently of the opening process. The closing spring can be manually charge (or recharged) by the charging handle or electrically loaded by a motor. The motor can be operated remotely to provide the operator with maximum safety.

    TOW45 Air Circuit Breaker

    What is the difference between a fuse and a circuit breaker?

    Before understanding the difference between them, you can briefly understand what a fuse is.

    What is a fuse?

    The fuse is composed of conductive material with a low melting point, which is connected between the positive poles of the two power terminals. If there is an abnormal overload current in this circuit, it will melt to protect other equipment from being damaged by the surge. Of course, a fuse lets normal current flow through it.

    Therefore, fuses also have different specifications to deal with different situations, and fuses of different specifications need to be used according to the usage scenarios.

    The difference between a six-point circuit breaker and a fuse is listed below:

    1. Can it be used repeatedly. After the fuse is blown, it cannot be used again, and the circuit breaker can continue to be used after it trips, provided that the circuit breaker itself has no problems

    2. Response time. Basically, a fuse has a much faster response time than a circuit breaker, meaning the fuse will open the circuit faster.

    3. Application scenarios. A single circuit breaker can be used to protect many devices, while a single fuse can only protect a single device.

    4. Protecting content. Fuses can only protect equipment from power overload, while circuit breakers can not only protect equipment from power overload but also prevent hazards caused by short circuits.

    5. Working principle. Fuses are thermal as well as electrical characteristics of conductive materials, while circuit breakers are electromagnetic and switching principles.

    6. Cost. A single fuse costs much less than a single circuit breaker.

    Open chat
    Can we help you?