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How do DC Circuit Breakers Work?

As their name suggests, Direct Current (DC) circuit breakers protect electrical devices that operate on direct current. The significant distinction between direct current and alternating current is that the voltage output in DC is constant. In contrast, the voltage output in Alternating Current (AC) cycles several times each second.

What is the Function of a DC Circuit Breaker?

The same thermal and magnetic protection principles apply to DC breakers as they do to AC circuit breakers:

Thermal protection trips the DC circuit breaker when the electric current exceeds the rated value. Bimetallic contact heats expand and trip the circuit breaker in this protective mechanism. The thermal protection functions faster because the current generates more heat to expand and open the electric connection as the current is considerable. The DC circuit breaker’s thermal protection protects against an overload current that is slightly higher than the typical operating current.

When strong fault currents are present, magnetic protection trips the DC circuit breaker, and the response is always instantaneous. Like AC circuit breakers, DC circuit breakers have a rated breaking capacity that represents the most significant fault current that can be interrupted. The fact that the current being stopped is constant with DC circuit breakers means that the circuit breaker must open the electric contact farther to interrupt the fault current. A DC circuit breaker’s magnetic protection guards against short circuits and faults far more extensive than an overload.

Things to Consider When Buying an AC Circuit Breaker

Because the protection mechanism for AC and DC currents is almost identical, the design of specific circuit breakers can work with both. It is, nevertheless, critical to double-check that the current type of the electric supply and the circuit breaker are identical. If you place the wrong circuit breaker, you cannot adequately protect the installation, and electric mishaps may occur!

Another significant factor to consider is the rated current of the electric cable that connects the DC circuit breaker to the protected electric equipment. An undersized cable can overheat, melting its insulation and generating an electrical fault, even if you correctly set the DC circuit breaker.

DC circuit breakers are available in miniature and molded case versions, like AC circuit breakers.

Three Types of Miniature Circuit Breakers:

  • Circuit Breakers Type B (trips at 3-5 times rated current).
  • Type C (trips at 5-10 times rated current).
  • Type D (trips at 10-20 times rated current).

Molded case circuit breakers are often larger and feature changeable protective levels.

DC Circuit Breaker in a Photovoltaic (PV) System

Photovoltaic systems have the potential to be a potent renewable energy mechanism. You can use one or more solar panels. In addition, you can use an inverter and other electrical and mechanical components to combine them. On the other hand, you must preserve the same systems and maintain them at all costs. The tiniest mishap in any function might quickly escalate into a significant issue for the entire setup.

As a result, DC breakers are essential components of a Photovoltaic (PV) system. It will cover the complete procedure of its operation, wiring, and safety precautions in detail below.

How Does It Work in a Photovoltaic (PV) System?

The most important question is: how do DC circuit breakers work? DC circuit breakers act the same way as AC circuit breakers, with heat and magnetic protection.

When the electric current exceeds the rated value, the thermal protection trips the breaker. The bimetallic contact heats up and expands as the current generates much more heat. Thermal protection can assist in current overloaded situations.

Magnetic protection in DC circuit breakers trips the breaker when many fault current is present. Even at their most extreme, DC circuit breakers can break fault current. Magnetic protection is vital in DC circuit breakers because it can prevent short circuits and other failures.

Why are DC Circuit Breakers Important for Solar PV Panels?

DC breakers are critical in solar Photovoltaic (PV) panels systems. Circuits for solar panels are a pricey component of the system. As a result, it is vital to safeguard them using a DC circuit breaker. You can connect the Solar PV System panels’ circuits to a combiner box. The DC circuit breaker also protects the circuits and boards.

It can turn the solar irradiation into direct current via photovoltaic solar panels, and photovoltaic installations require the use of DC circuit breakers. Even a minor discrepancy might be highly costly. In the case of electric vehicles, you can use the EV charging stations to recharge their batteries. Technicians set up the system here to work with direct current. As a result, DC circuit breakers are required in these systems to avoid any mishaps. Because they both use direct current, photovoltaic solar panels and electric vehicles can work well together. It is also unnecessary to convert this direct current to an alternating current. You can easily control the automatic systems with DC circuit breakers. That occurs for them to be able to respond quickly.

Products Available


This DC Circuit breaker is the best fit for homes that can use up to 750V 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 broader utilization.


This product can also hold up to 1000 volts of current with a 63A rated current. It also provides sufficient protection from short circuits, overload, and infrequent operations. You can use it in DC applications like photovoltaic systems, communications, and many more.

Although both the products are perfect for domestic usage, the GYM9 DC-6KA 4P MCB for PV can handle a capacity of BCD, while the GYM9 DC-6KA 3P MCB For PV also can handle BCD capacity. Also, there are four poles in 4P MCB, while there are just three poles in 3P. That means that the 4P MCB can handle the same capacity of current when compared to the 3P MCB.


DC circuit breakers are less prevalent than AC circuit breakers, but they’re just as significant because the users can use them in households and businesses. DC circuit breakers are a relatively new technology for homeowners, as most household gadgets operate on alternating currents. They play a critical part in the electrical protection of high-cost energy-efficient technologies like LED bulbs, photovoltaic solar panels, and electric cars. DC circuit breakers will have a larger market as these technologies reach a wide range of consumers. On the other hand, DC circuit breakers are a well-established and well-known technology in the commercial world. They play a significant part in protecting high-precision machinery and arc welding.

When an electrical system necessitates the use of DC circuit breakers, it is usually advisable to retain the services of expert engineers and technicians to ensure that you can choose and install the proper smart breaker

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