Circuit breakers are essential for the safety and efficiency of electrical installations, protecting against overloads and short circuits. With different types and characteristics, each circuit breaker is designed to meet specific needs, whether in residential, commercial, or industrial environments.
In this article, we'll explore the three main types of circuit breakers: miniature circuit breakers, molded-case circuit breakers, and air circuit breakers, so you can choose the best one for your project. Stay tuned!
Miniature circuit breakers
Miniature circuit breakers are compact electrical protection devices designed to interrupt currents in low-voltage circuits. They are widely used in residential and commercial installations to protect against overloads and short circuits.
The breaking capacity of a miniature circuit breaker ranges from 2A to 125A, depending on the manufacturer and application. Standard NBR NM 60898 defines the instantaneous actuation curves (B, C, and D) for miniature circuit breakers, which are adjusted according to the circuit protection needs.
It's important to note that miniature circuit breakers are not suitable for protecting electric motors, as they can trip during inrush current. For terminal circuits in buildings and similar systems, miniature circuit breakers are ideal, providing efficient and safe protection that's easy to operate by unqualified personnel.
Therefore, when installing, it is essential to consider the interrupting capacity and the correct specification to avoid undersizing and ensure the safety of the installations.
Molded case circuit breakers
You circuit breakers Molded-case circuit breakers are robust protective devices designed to interrupt high electrical currents in low-voltage circuits. Their main feature is their ability to withstand and interrupt large currents, with ratings ranging from 16A to 3200A.
Therefore, they are widely used in industrial and commercial environments, as well as in power distribution panels. After all, they offer adjustable thermal and magnetic protection, allowing for greater precision in protection against overloads and short circuits.
Molded case circuit breakers are essential in locations where high interrupting capacity and robustness are required—such as in motor circuits, generators, and power distribution systems.
Additionally, accessories can be added and their settings adjusted. Therefore, these circuit breakers are highly flexible and adaptable to the specific needs of each installation.
Open box circuit breakers
Air-type circuit breakers are high-capacity electrical protection devices. They are used in large installations, such as industrial plants, power plants, and substations.
These circuit breakers are designed to withstand very high electrical currents, being able to conduct up to 6300A and interrupt short-circuit currents greater than 300kA, depending on the model.
Air circuit breakers offer a wide range of settings and protections, including overload (function L), short-time delayed short-circuit (function S), instantaneous short-circuit (function I), neutral conductor protection (function N), and earth fault (function G).
These circuit breakers are selective, allowing for greater control and coordination in protecting the electrical system. Furthermore, they can be equipped with various accessories and communication modules.
Comparison table between miniature circuit breakers, molded case and open case
To more easily understand the 3 circuit breaker models we are working on in this content, we have created the following table:
|
Feature |
Miniature circuit breakers | Molded Case Circuit Breakers | Open Box Circuit Breakers |
|
Current capacity |
2A to 125A | 16A to 3200A | Up to 6300A |
|
Interrupting capacity |
3kA to 20kA | Up to 200kA |
Above 300kA |
|
Common applications |
Residential and commercial installations | Industries, distribution boards, motors |
Industries, plants, substations |
|
Thermal and magnetic protection |
Yes | Yes, adjustable |
Yes, with various adjustments
|
|
Performance curves |
B, C, D | L, S, I, N, G |
L, S, I, N, G |
| Cost | Lower cost | Intermediate cost |
Higher cost |
Trifásica Elétrica offers a wide range of low voltage circuit breakers, including miniature circuit breakers, molded case circuit breakers and open case circuit breakers.
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