What is the Definition of a Miniature Circuit Breaker?

A Miniature Circuit Breaker (MCB) is a self-acting electrical switch employed for safeguarding low voltage electrical circuits from damage that results from excess current caused by overloads or short circuits. The functionality of MCBs is analogous to fused isolators; however, MCBs are reusable even after the circuit is interrupted following an overload or short circuit. Additionally, MCBs are more sensitive to faults in comparison to fuses.

The Functioning Principle of the DC MCB

The working principle of an MCB encompasses two operation arrangements. One arrangement is attributed to the thermal effect of overcurrent, while the other is ascribed to the electromagnetic effect of overcurrent. The thermal operation of MCBs relies on the deflection of a bimetallic strip when there is continuous overcurrent flow. The strip is heated and bends, which causes a mechanical latch to be released. Since the mechanical latch is attached to the operating mechanism, it triggers the opening of the miniature circuit breaker contacts. On the other hand, during short-circuit conditions, the sudden increase in current causes electromechanical displacement of a plunger that is connected to the tripping coil or solenoid of the MCB. The plunger then hits the trip lever, which promptly releases the latch mechanism, leading to the opening of the circuit breaker contacts.


Why to choose a DC MCB with Non-Polarity?

The selection of non-polar direct current (DC) micro-breaks in energy storage systems can bring about various advantages. Compared to traditional DC micro-breaks, non-polar DC micro-breaks are more effective in offering reverse current protection, as the incoming and outgoing lines do not differentiate between positive and negative. This allows the circuit to be protected from both directions, ensuring the reliable operation of solar photovoltaic power generation systems.

On the contrary, traditional polarized DC micro-breaks can only protect circuits from one direction, and cannot effectively break the current in the opposite direction, leading to potential malfunctions and accidents. In addition, if the positive and negative poles are connected in reverse, a short circuit will occur, which will cause the current to directly connect the positive and negative poles of the power supply, leading to a large current that can burn the wires and power supply. Such short circuits can also cause malfunctions and accidents, including fire, which is dangerous and harmful.

To mitigate these risks, the ONCCY Non-polarity miniature circuit breaker can adjust the distance between the moving and static contacts, shorten the arc jumping distance, and increase the arcing coil. As a result, the DC arc can enter the arc extinguishing chamber more smoothly from either direction, and the arc can be cut into smaller arcs through the arc extinguishing grid, effectively cutting off the fault and providing a higher level of safety for energy storage systems.

In summary, the use of non-polar DC micro-breaks in energy storage systems can provide effective reverse current protection and ensure reliable operation, while traditional polarized DC micro-breaks can lead to malfunctions, accidents, and potential fire hazards. By employing innovative technology like the Aswich Non-polarity miniature circuit breaker, these risks can be mitigated, and energy storage systems can operate more safely and efficiently.

The Two Types of DC MCB

DC miniature circuit breakers (MCBs) come in three types, each with unique characteristics. Type B DC MCBs trip at a current range of 3 to 5 times their rated current. They are best suited for low switching surge inductive or resistive loads in household and light commercial settings.

Type C DC MCBs trip at a current range of 5 to 10 times their rated current. They are typically used in fluorescent lights and small motors that experience high inductive loads and switching surges. These MCBs are more appropriate for industrial and commercial settings that require high induction.

Products Available

There are many products available on the Onccy.com,official website that you can buy. Some products are listed below:


EDB1-63 3P 蓝色手柄

This DC circuit breaker is the best fit for homes that can use up to 1200V with a rated current of 63A line. It can help in protecting overload, short circuit, and infrequent operation. It has an indicator function, transparent cover and can adapt to broader utilization.


EDB1-125 2P 蓝色手柄

This product can also hold up to 200 volts of current with a 250A rated current. It also provides sufficient protection from short circuits, overload, and infrequent operations. You can use DC applications like photovoltaic systems, communications, and many more.


How to choose a Non-polarity DC breaker for an energy storage system?

When selecting a Non-polarity DC breaker for an energy storage system, several important factors should be considered. The first of which is determining whether it is polar or non-polarity. It is recommended to choose non-polar DC micro-break products for energy storage systems. Secondly, the application field should be taken into account, with two options available on the TUV certification: DC systems and PV systems. It is strongly advised to select products that have passed the DC SYSTEM test, as the standards for this test are much stricter than those for PV SYSTEM. ONCCY’s Non-polar DC micro-breaks have successfully passed both the DC SYSTEM and PV SYSTEM tests, making it an ideal choice for both photovoltaic and energy storage systems.

The third consideration is the rated working voltage Ue, which should be selected based on the parameters of the energy storage system. Similarly, the fourth consideration is the rated current In, which should also be selected based on the parameters of the energy storage system. When it comes to the fifth consideration, the rated short-circuit breaking/interrupting capacity Icu & Ics, it refers to the circuit breaker’s ability to safely cut off the fault current. This function is not necessarily related to its rated current and is typically divided into limit breaking capacity Icu and operating breaking capacity Ics. Choosing a circuit breaker with a higher breaking capacity can provide better protection for the energy storage system.

ONCCY’s non-polar DC micro-break has a breaking capacity of up to 10KA, which can greatly enhance the safety of your energy storage system. The sixth consideration is the tripping curve, where B curve or C curve is usually chosen based on the application scenario. Lastly, the commonly used international certifications are CE, CB, TUV, SAA, and UL, which can be selected based on the regulations of the country where the project is located. ONCCY’s non-polar DC micro-break has passed CE, CB, TUV, SAA, and UL, providing safety protection for energy storage systems worldwide.