Circuit Breaker

Manhua Electric: Your Professional Circuit Breaker Supplier!

Our staffs of Manhua Electric have over thirty years of experience in the production and export of electrical products. Our main products include switchboards, automatic transfer switches (ATS), circuit breakers, contactors, lightning arresters, photocells and timers. Starting in 2017, we started operating a warehousing center in Chicago, USA. As a supplier of United Nations tender projects, we have been participating in power construction projects in overseas markets.

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Good Reputation
We have cooperated with partners in Saudi Arabia, Kuwait, Thailand, Vietnam, Japan and other countries, and have gained their trust because of the excellent quality of our products.

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Quality Guaranteed
We ensure that all production processes are carried out in accordance with the ISO9001 system, and all products have passed CE certification, and some products have also passed UL and VDE certification.

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High Productivity
We have our own standard factory buildings and warehousing centers, which can supply electrical products in large quantities and independently complete all work from raw materials, product production, assembly to packaging.

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Warm Service
We sincerely welcome all customers who come to inquire about our products, and provide professional product knowledge and technical guidance, as well as complete warranty and after-sales services.

What is Circuit Breaker?

A circuit breaker is an electrical safety device designed to protect an electrical circuit from damage caused by over current. Its basic function is to interrupt current flow to protect equipment and to prevent the risk of fire. 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. They are made in varying sizes, from small devices that protect low-current circuits or individual household appliances, to large switchgear designed to protect high voltage circuits feeding an entire city.

Features of Circuit Breaker

High Security

Our circuit breakers are equipped with power management features to block power surges to avoid battery rupture and explosion caused by short circuits, protecting your motors from electrical damage.

Stable Operation

The copper lugs of these circuit breakers provide a highly conductive connection between the circuit breaker and the wire and also prevent the formation of oxide layers.

Resettable Structure

These circuit breakers have a pull-to-trip lever that can be used as a switch. They combine switching and circuit protection into one device, allowing quick manual reset operation for a quick reset

Waterproof Design

Made with rust-proof bolts and a corrosion-resistant housing, these circuit breakers can be fixed to an electrical panel or other mounting location and prevent water or moisture from entering and causing damage.

Application of Circuit Breaker

Replacement of Fuse

Compared to another switchgear-like fuse, a circuit breaker is smaller in size and can be automatically reset for repeated operation. A circuit breaker can be automatically reset post-repair of the circuit and ensures continuous supply. Using a circuit breaker instead of a fuse eliminates the cost of replacement, saves time, and enables high-voltage operation.

As a Switch

The circuit breaker can also act as a switch that manually turns on and turns off the power supply to electrical equipment in the power system. It can be used as a switch to manually turn on and turn off the supply for repair or replacement purposes. When power system components like transformers, coils, and other equipment or circuit breakers need to be repaired or replaced, a circuit breaker isolates those components.

Switch Loads

Circuit breakers are used in switching different kinds of loads in households, commercial, buildings, and industrial places. They are used as switchgear to protect electrical equipment in household and commercial areas from faulty current, overcurrent, short-circuit, and fire.

Types of Circuit Breaker

Low Voltage Circuit Breakers (V < 1000 Volts)

Miniature Circuit Breaker (MCB): MCB (Miniature Circuit Breaker) is one of the most popular household circuit breakers that operate for low voltages. It can be turned on and off manually and works through magnetism. The bimetallic strip in the MCB senses the overcurrent and releases a mechanical latch. MCB comes in various types such as A, B, C, D, G, H, and K.

Air Break Circuit Breaker: Air Break circuit breakers are used in low voltage applications with a less contact life of about 6 short circuits. This circuit breaker is of two types- plain air break and magnetic blow-out air break circuit breakers. The air break circuit breaker employs the method of high résistance interruption for arc quenching. The resistance of the arc is increased by reducing the area of the cross-section and increasing the length of the arc. Arc can also be quenched by cooling and spitting it inside the circuit breaker.

Medium Voltage Circuit Breakers (1 kV - 33 kV)

Minimum Oil Circuit Breaker (MoCB): Oil circuit breakers generally use transformer oil as an insulating medium to extinguish the arc. It is because oil is a good dielectric medium having a high dielectric strength of 110 kV/cm. The ions meant for producing the arc react with oil to release gasses like hydrogen (70-80%), methane, ethylene, and acetylene. Since hydrogen is a good conductor of heat, the hydrogen bubble near the contact cools down the system to promote de-ionization for the production of the electric arc. The turbulence of oil in the arc path is another factor that forbids its production. The contact life of such circuit breakers is around 6 short circuits and is more likely to be replaced frequently.

Vacuum Circuit Breaker: A vacuum circuit breaker uses a medium with pressure less than that of the atmospheric pressure i.e. pressure less than 760 mm of Mercury. Unit Torr (1 mm of Hg) is used to measure such low pressures. In vacuum circuit breakers, a vacuum arc quenching medium of 10-5 to 10-7 Torr is used. The dielectric and insulating strength of the medium is the highest among other circuit breaker mediums. The presence of the vacuum allows micro projections to produce metal ions and form an electric arc. The vacuum breaker is fast enough to interrupt the faulty current within the very first cycle. The explosion possibility of the vacuum circuit breaker is NIL and it offers a contact life of about 100 short circuits.

High Voltage Circuit Breakers (33 kV-220 kV) and Extremely High Voltage Circuit Breakers (V > 400 kV)

Air Blast Circuit Breaker: Air blast circuit breakers are used as a replacement for oil for medium, high, and extremely high voltages. However, air blast circuits are frequently used for high voltages of more than 110 kV. High-pressure air or compressed air is used as a method for quick arc quenching instead of other gasses like nitrogen, carbon dioxide, and hydrogen. The choice of air instead of other gasses reduces the cost and size of the circuit breaker. Due to the presence of air instead of oil, there is no risk of fire. The contact life of air blast circuit breakers is around 25 short circuits and they offer re-closures (reuses).

SF6 Circuit Breaker: Sulphur Hexafluoride Circuit Breaker uses SF6 gas for extinguishing the arc in high and extremely high voltage applications. The sulfur hexafluoride gas has high dielectric strength and electronegative properties of absorbing the free electrons. The gas produces negative ions which are relatively slower than free electrons to enable ionization for arc generation. The contact life of SF6 circuit breakers is around 25 short circuits and the same gas can be used after operation. Other features include a low risk of fire, and non-explosive, noble, and non-poisonous properties.

Components of Circuit Breaker

The Frame

The frame is the body of the circuit breaker. It’s an external shell that encloses and protects all the other components. The material used to make this casing determines how much current the breaker can accommodate.
For instance, a metal-clad frame is used for circuit breakers designed for high-voltage circuits. On the other hand, the insulated and moulded cases are for medium and low-voltage circuit breakers, respectively. Apart from protecting the rest of the components, another purpose of the frame is to hold the breaker in position in the consumer unit (CCU) box.

Operating Mechanism

The breaker’s operating mechanism is another part that plays a vital role in the overall operation of this electrical mainstay. It provides a means of turning the circuit on and off by closing and opening the breaker contacts.
Most circuit breakers today use the quick-make, quick-break toggle mechanism. In this system, the contacts close or snap open quickly regardless of the speed used to move the handle. This handle is designed to show three conditions: on, off, and when the circuit is opened automatically. In the case of the third scenario, you’ll need to move it to the off position before switching it on.

Trip Unit

The trip unit is the most important component in any circuit breaker because it activates the operating mechanism. Considered the brain of the breaker, it detects an overload or short circuit and triggers the operating mechanism to open the contacts. The trip units used today are electronic, and their advanced nature offers flexible mounting configurations. As such, it’s easier to design a breaker system based on the application.

Contacts

The electrical contacts allow the flow of current in the breaker when the circuit is closed. A typical electric circuit breaker has two types of these components: fixed and floating contacts. The breaker controls the floating contact, and it moves away from the fixed contact when the breaker trips. As a result, the flow of current to the load is broken.
While discussing the power supply system, it’s also worth mentioning another set of vital parts of a circuit breaker the terminal connectors. They connect the breaker system to the power source and the load. Moreover, these components are electrically connected to the contacts, controlling the load’s power supply.

Arc Extinguisher

When the operating mechanism is called to action, arcs are drawn between contacts as the breaker interrupts the flow of the current. This arc of electricity can reach very high temperatures and damage the circuit breaker. To prevent this from happening, the arc extinguisher provides a quenching mechanism to help solve the problem. This component contains a series of contacts designed to open gradually and divide the arcs, making it easier to extinguish.

Standard Current Ratings of Circuit Breaker

Circuit breakers are manufactured in standard sizes, using a system of preferred numbers to cover a range of ratings. Miniature circuit breakers have a fixed trip setting; changing the operating current value requires changing the whole circuit breaker. Larger circuit breakers can have adjustable trip settings, allowing standardized elements to be applied but with a setting intended to improve protection. For example, a circuit breaker with a 400 ampere "frame size" might have its over current detection set to operate at only 300 amperes, to protect a feeder cable.

For low voltage distribution circuit breakers, International Standards, IEC 60898-1 defines the rated current as the maximum current that the breaker is designed to carry continuously. The commonly available preferred values for the rated current are 1 A, 2 A, 4 A, 6 A, 10 A, 13 A, 16 A, 20 A, 25 A, 32 A, 40 A, 50 A, 63 A, 80 A, 100 A, and 125 A. The circuit breaker is labeled with the rated current in amperes prefixed by a letter, which indicates the instantaneous tripping current that causes the circuit breaker to trip without intentional time delay expressed in multiples.

Circuit breakers are also rated by the maximum fault current that they can interrupt; this allows use of more economical devices on systems unlikely to develop the high short-circuit current found on, for example, a large commercial building distribution system.

Using Benefits of Circuit Breaker

Make Enough Electrical Current Available
Electrical current requirements for major appliances are far higher than those for lighting and other minor appliances. Your home’s electrical system would be immediately overloaded if you connected your dishwasher or electric range to a standard electrical outlet. You can make sure your device receives enough electrical current with a dedicated circuit without having to worry about overcharging the other outlets in your home.

Eliminate Electrical Safety Risks
Installing dedicated circuits all around your house can help to keep your electrical system safe and secure. An appliance may put your home at risk for an electrical fire if it is connected to a standard circuit rather than a dedicated one. You’ll feel more at ease after your new appliances are installed if you invest in dedicated circuits.

Observe the National Electrical Code
The National Electric Code mandates that all major appliances be wired to separate circuits. To avoid violating the National Electric Code and paying high fines, create separate circuits before adding your next appliance. The National Electric Code was created to make sure that all residential and commercial properties are protected from electrical safety threats.

Factors to Consider When Choose Circuit Breaker

Testing and Maintenance

One major factor to consider when finding the right circuit breaker is testing. You can test a good circuit breaker regularly, about once a year. If you live in an area with extreme weather, consider testing it more frequently. In addition to testing, you want a circuit breaker that is easy to maintain. If testing reveals an issue, you must fix your circuit breaker or get some professional to maintain it and point out any issues.

Maximum Interrupting Capacity

Another important factor to consider is maximum interrupting capacity (MIC). The MIC is the highest current the breaker can interrupt, and more appliances and electronics require a higher MIC. An MIC of 10,000 amps is standard, but it’s easy to trip this when using multiple appliances simultaneously. Larger businesses need higher MICs to function safely and avoid constantly tripping the breaker.

Voltage Rating

The circuit breaker should prevent current irregularities, so voltage is another factor to consider. The voltage rating is essential for safety, ensuring the circuit breaker can safely trip when overloaded. While most homes have low-voltage circuit breakers, businesses and areas with power lines use medium or high-voltage circuit breakers. Find a circuit breaker with the same or higher rating than the open-circuit voltage, as it can prevent explosions or arcing when a short circuit happens.

750VDC 250a 4p MCCB DC Molded Case Circuit Breaker

Frequency

Frequency is another important factor, as you want something below 60 Hertz. Typical circuit breakers have a frequency range between 50 and 60, so stay in that range. Regularly going above 60 Hz can degrade the circuit breaker and reduce its power rating. A lowered power rating can hurt your circuit breaker and prematurely age it.

Adjustable Moulded Case Circuit Breaker MCCB

Setup

In addition to the circuit breaker’s standards, you must consider how you’ll install it. You don’t want to expose it to too much heat or sunlight, and you also want low moisture. Too many variables like this can damage the circuit breaker and lower its ability to protect your electronics from power surges.

What Causes a Circuit Breaker to Trip？

Breakers can trip for a few reasons but with the same purpose in mind – to keep you safe. So be mindful if you’re planning to reset the breaker. Here’s how to know when it is safe or not.

Overloaded Circuit
The most common cause of a circuit breaker tripping is too much current being drawn by lighting, devices or appliances on a given circuit, overloading it. Overloading wiring in a circuit generates immense heat, which can cause a fire.

Is it safe to reset the breaker when it tripped from an overloaded circuit? Depending on the age and design of your home, overloads can be somewhat common but normally easy to pinpoint. If a breaker tripped when on the initial use of an appliance or light, it is possible that is what overloaded it.

Short Circuit
The wiring in your home consists of three different types of wires: a live or hot wire, a neutral wire, and a ground wire. When a live wire comes into contact with the neutral wire, a ‘short’ occurs, allowing a lot of current to flow and overload the circuit. Short circuits are generally a much bigger problem than a circuit overload, as they can potentially create a risk of both fires and electrocution. A specific type of short circuit, a ground fault surge, occurs when the hot wire touches either the ground wire or a metal electrical box that the ground wire is connected to.

Old or Faulty Circuit Breakers
Though not nearly as common as the above causes, a circuit breaker might trip – not due to a problem with the circuit – but with the breaker itself. If your breaker or your electrical panel is old, faulty, or not wired properly, it can also cause the breakers to trip. Remember, repeatedly resetting a breaker could result in an arc flash or a fire. If the circuit is not overloaded and the breaker trips after one attempt at resetting it, leave it in the tripped state. It is essential that you contact a professional electrician to determine the source of the problem.

On the other hand, outdated breaker boxes can have worn connectors, and a breaker may not trip when it should, which can cause a circuit to overload and start an electrical fire.

How Do You Reset a Tripped Circuit Breaker?

If your circuit breaker and fuse aren’t accessible or labeled, it’s a good idea to take the time to figure out each switch or fuse and the area it controls. Then, when a circuit or fuse trips or blows, you’ll know exactly which one it is.

To reset your circuit breaker, turn off the breaker by moving the switch or handle to the “off” position. Then, turn it back on. For safety, it’s a good idea to stand back from, or to the side of, the panel, just in case any sparks come from the breaker when it’s moved. You might even consider wearing safety goggles to protect your eyes.

If a circuit breaker trips due to exceeding its maximum amperage, its switch handle will have moved between the “on” and “off” positions. You may see a red area indicating that the circuit breaker has tripped. However, it depends on your electrical panel. For some panels, the trip only causes a minimal movement of the handle; in that case, you’ll need to look closely at the switches to figure out which one has tripped.

It's best to prepare for a power outage ahead of time. Remember to keep a flashlight and batteries near the electrical panel to help illuminate the area if the power is off (and if you can’t use the flashlight on your cell phone to preserve its battery). Wait a few minutes after resetting the circuit breaker before unplugging and plugging in your various appliances to try and figure out what specifically overloaded the circuit or caused the trip.

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Frequently Asked Questions of Circuit Breaker

Q: What is a circuit breaker used for?

A: By definition a circuit breaker is an electrical safety device, a switch that automatically interrupts the current of an overloaded electric circuit, ground faults, or short circuits. Circuit breakers "trip", shut off, current flow after protective relays detect a fault.

Q: What are the three types of circuit breakers?

A: There are three basic circuit breaker varieties: standard breakers (which include both single-pole and double-pole circuit breakers), ground fault circuit interrupter circuit breakers (GFCIs) and arc fault circuit interrupter circuit breakers (AFCIs).

Q: Which circuit breaker is used?

A: The most widely used electrical circuit breakers for domestic electrical connections are Miniature circuit breakers (MCBs) Residual current circuit breakers (RCCB) and Mounded Case Circuit Breaker (MCCB).

Q: Can I use circuit breaker as a switch?

A: It's quite evident that though they share a similar function on a basic level, they are two separate entities. Circuit breakers may work as effective as safe switches, but they are not switches. They are not interchangeable. Therefore, using a circuit breaker as a switch is not recommended.

Q: What happens without a circuit breaker?

A: Without working circuit breakers, any electrical issues could potentially start a fire or even electrocute you when you turn on the lights or plug something into an outlet. While this is obviously great in terms of safety, it can still be frustrating when you have a circuit that is constantly getting tripped.

Q: Which type of circuit breaker is best?

A: There are different types of low-voltage circuit breakers; Miniature Circuit Breakers (MCB) are used for handling current below 100 amps. They are a favorite for applications that don't have high currents. If your application has current exceeding 100 amps, a molded-case circuit breaker (MCCB) might be ideal.

Q: How long does a circuit breaker last?

A: Most common circuit breakers last 30-40 years. Electrical panels can last for decades but should be inspected every 10-30 years. In fact, it typically happens over a period of time. As components like breakers and switches in your panel overheat due to heavy use and high temperatures, materials will begin to wear out. This is when you'll start to notice signs of burning in your panel.

Q: Do all houses have circuit breakers?

A: All homes have a circuit breaker box, electrical panel, fuse box, or breaker panel. While it goes by many names, “fuse box” is technically incorrect. This includes Housing Board flats and private residences. Homeowners have a two-year grace period to install the RCCB. Failure to do so by July 1, 2025 may result in a fine of up to $5,000.

Q: What happens if a circuit breaker is overloaded but not tripped?

A: If your circuit breaker is overloaded and fails to trip, it can lead to dangerous consequences, like an electrical fire. If you hear, see, or smell signs of fire, leave the home and call 911. If the circuit breaker does not trip, then the overload could damage the wiring. With the power continuing to flow through damaged wiring, an electrical fire could occur.

Q: Is it safe to turn off circuit breaker?

A: The danger is minimal if all you're doing is shutting off a circuit breaker, since you won't be removing the entire panel cover to expose the service wire connections or the hot bus bars inside. This is a sign that one of your circuits is getting overloaded on a regular basis. Your circuits are only able to handle up to a certain level of voltage. Beyond this voltage, you run the risk of starting an electrical fire. This is why the circuit breaker trips, shutting off the flow of electricity in your home.

Q: How many amps is a circuit breaker?

A: The standard for most household circuits are rated either 15 amps or 20 amps. An important note to remember is that circuit breakers can only handle about 80% of their overall amperage. That means a 15-amp circuit breaker can handle around 12-amps and a 20-amp circuit breaker can handle about 16 amps.

Q: Do circuit breakers use AC or DC?

A: The circuit breakers are used to break electric power. DC power is used because it allows for a battery bank to supply close/trip power to the breaker control circuits in the event of a complete AC power failure. While dc breakers are commonly used in industrial sections, AC circuit breakers can be found in residential units as well. AC carries the importance of being easy to extinguish the arc at a crossing point. This takes place because AC has a zero-crossing point in each cycle.

Q: Can I use MCB instead of RCCB?

A: Many people use MCB rather than using RCCB because in earlier times, MCB was the only option which was available. Thus, many people rely on it rather than RCCB. In the case of RCCB, the fault zone of the electrical circuit can be easily identified.

Q: Which is better fuse or circuit breaker?

A: Fuses offer circuit protection that is inexpensive, straightforward and fast protection. Their faster circuit protection time is perhaps their biggest benefit over circuit breakers. This is important when protecting sensitive electronic equipment. Circuit breakers provide better protection for three-phase applications.

Q: Do I need RCCB if I have ELCB?

A: If you have an Earth Leakage Circuit Breaker (ELCB) installed in your home, you do not need to change it to a Residual Current Circuit Breaker (RCCB). Both the ELCB and RCCB are electrical safety devices that cut off the electricity supply immediately upon detecting leakages that may result in an electric shock.

Q: Why do people trip on ELCB?

A: An Earth Leakage Circuit Breaker (ELCB) trips when there is an earth fault or leakage in a circuit or equipment，such as some water heaters, washing machines and cookers may cause the ELCB to trip. If the ELCB trips repeatedly and doesn't reset, it means there is a fault in the system. ELCBs introduce additional resistance and an additional point of failure into the Earthing system.

Q: Why is my breaker on but no lights?

A: This indicates that either the receptacle tripped or it's not working properly. Hit the 'RESET' button on the GFCI to reset the circuit breaker. If this doesn't fix the issue, you can also try testing your GFCI to see if it needs replacing. GFCIs need annual testing to ensure they're protecting your outlets.

Q: How do I know if my breaker is still good?

A: The multimeter has two prongs. Touch one prong to the circuit breaker's terminal screw and touch the other prong to a ground screw, usually on a metal bar along the right side of the circuit box. The multimeter should read a between 120 and 240 volts. Anything else indicates a faulty circuit breaker.

Q: What is the difference between a circuit breaker and a main breaker?

A: Main breaker: Large two-pole circuit breaker that limits the amount of electricity coming in from outside to protect the circuits it feeds. It also identifies your breaker panel's amperage capacity. Circuit breakers: Stacked in the panel and have an ON/OFF switch that controls the flow of power.

Q: Can a house have two circuit breakers?

A: It is possible to have up to six breakers to control subpanels and other circuits; however, most main panels have one main breaker. Many may have a fused disconnector that may be pulled out instead. Sometimes homes have two circuit breaker panels controlling power to different parts of a house, such as a large addition or a second story, for example.

As one of the most professional circuit breaker manufacturers and suppliers in China, we're featured by quality products and competitive price. Please rest assured to buy buy customized circuit breaker made in China here from our factory. Contact us for quotation.

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