What is a circuit breaker? Why are there different types of circuit breakers? What is the circuit breaker curve for? In this article, the World of Electrical answers these questions, in addition to telling you everything you need to know about these important electrical components. So come on guys!
Breaker, what is it?
Circuit breakers are components used in residential, commercial and industrial switchboards, with the main objective of protecting electrical circuits. The circuit breaker is a mechanical device that was designed to act when it receives an overload current
So, when the circuit breaker trips it is protecting the cables and consequently the electrical equipment of that circuit, preventing a current greater than the supported limit from reaching them. Now you know that locking the circuit breaker is not a very smart choice, is it?
Many people think that the circuit breaker and the fuse perform the same function, but although they act as protective devices, their characteristics are quite different! One of the main differences is that after being tripped, the circuit breaker can be reset several times, while the fuse must be discarded after its first blow.
Types of circuit breakers
In addition to the correct dimensioning, the choice of the most appropriate type of circuit breaker is essential to ensure the efficiency of an electrical installation. Among the main types of circuit breakers, we can mention the thermal, magnetic and thermomagnetic. These concepts are directly related to the circuit breaker actuation mechanism.
The image below shows the working principle of the thermal breaker which is based on the deformation of a bimetallic blade. When this blade receives an overload the temperature on it deforms one of the metals differently from the other, creating a curve, this effect causes the mechanical contact to be opened and with this, the protection of the electrical equipment of this circuit occurs!
The thermal breaker is a device with a very simple mechanical characteristic, it is robust and inexpensive. The negative point is that it has a relatively slow action time, making this type of circuit breaker suitable against overload, but not the most suitable for short circuit protection.
Magnetic Circuit Breaker
The following image shows the operating principle of the magnetic circuit breaker which is based on electromagnetism. When there is some variation in electrical current passing through the coil turns, the magnetic field generated causes the metal plate of the contact to be attracted by opening the contact, and this consequently protects the electrical equipment of this circuit.
The magnetic circuit breaker is a high-precision device, with an almost instantaneous effect! And it is thanks to this instantaneous interruption speed that the magnetic circuit breaker offers protection against short circuit. The negative point is that this type of circuit breaker has a much higher cost.
Thermomagnetic circuit breaker
As its name suggests, the thermomagnetic circuit breaker is the junction of the magnetic and thermal circuit breaker. Of the types of circuit breakers mentioned so far, this is the most used in commercial and residential installations.
Among its main characteristics, we can mention the maneuver, which is the voluntary closing and opening of the circuit. In addition, the thermomagnetic circuit breaker offers protection against overload, as does the thermal circuit breaker. It also offers protection against short circuits, as well as the magnetic circuit breaker.
Circuit breaker categories
As we already said, the dimensioning of the circuit breaker is a fundamental part to guarantee the safety of the electrical installation! It is necessary to understand that there is an appropriate category of circuit breaker for each type of load, and it is precisely these categories that will indicate th
Rest assured, because it is very simple to understand! When the equipment is sensitive it needs a type of circuit breaker that has a very fast actuation time. In the case of very powerful motors, for example, the circuit breaker must have a slower operating time. Therefore, it is the curves of the circuit breakers that determine the time and current limits that the device supports.
Curved circuit breaker B
B-circuit breakers have an actuation current of 3 to 5 times greater than their rated current. For example, the actuation curve of a 20A circuit breaker varies between 60 and 100A. This type of circuit breaker is widely used in circuits with resistive loads, for example, electric heater, shower, toaster, electric oven, iron, etc.
C curve circuit breaker
The C curve circuit breakers have an actuation current of 5 to 10 times greater than their rated current. For example, the actuation curve of a 20A circuit breaker varies between 100 and 200A. This type of circuit breaker is widely used in circuits with inductive loads, such as lighting circuits, transformers, small motors, microwaves, sound equipment, television, computers, etc.
Curved circuit breaker D
D-curve circuit breakers have an actuation current of 10 to 20 times greater than their rated current. For example, the actuation curve of a 20A circuit breaker varies between 200 and 400A. This type of circuit breaker is widely used in industrial circuits such as a welding machine, generator, air conditioning , compressor, large engine, hydraulic pump, washing machine, etc.
Maybe you’re wondering, but where is the A curve breaker? This type of circuit breaker does not exist, because the electrical A is used for Amper and this could cause confusion! So now you know why the circuit breaker curves start with letter B.
The use of the circuit breaker is mandatory in electrical installations, but many people have no idea what types of circuit breakers are, let alone where they should be used. Below is a video from the Mundo da Elétrica channel on circuit breaker sizing, it is very worth watching to learn more and more!
Do you know someone who is always complaining that the circuit breaker turns off when going to shower? Submit this article and help us spread this important information. You may not know it, but the incorrect sizing of cables and circuit breakers may be the cause of the high value on your e