Anyone who works with electricity has heard these terms many times, but what are overloads and short circuits and what type of protection should we use to protect ourselves against each case?
In this article we will explain the difference between each of them and the type of protection to use to protect against each case or both!
Enjoy reading!
In general, a short circuit happens when we connect a circuit directly between phase-to-phase, phase-to-neutral or phase-to-ground, causing the current to rise sharply, causing equipment to burn or protections to trip. Overload, as its name suggests, is the excess load on the circuit, caused by too many equipment connected to the same circuit.
Overload
Overload is the term used when an electrical load requested in a circuit is above the limit that it can support. One of the most frequent causes of overload is the connection of too many devices to the same socket circuit using adapters or extension cords.
Another serious problem found in homes and industries is the installation of equipment without an adequate study of loads and selectivity, causing overload in the general panels and sometimes even in the power transformer.
Overload can cause, in more serious cases, damage to conductors, sockets, generators and/or transformers, causing a short circuit and potentially leading to damage to equipment and even fires.
For this reason, it is very important to correctly size the protection device and circuit conductors so that, in the event of an overload, damage is minimized.
Short circuit
In a more explanatory way, the short circuit, as the name suggests, is the shortest path that the electric current takes in a circuit. When two conductors in the same circuit are interconnected, the resistance drops suddenly and the current increases suddenly, causing this effect.
For single-phase and two-phase circuits, U=RxI where U is the circuit voltage, R is the resistance and I is the current; As the voltage is constant, if we suddenly reduce the resistance, the current will increase.
The longer the installation is exposed to a short circuit, the greater the damage caused by it. Therefore, it is very important, when sizing a protection device, to pay attention to the maximum short-circuit current between phase-to-phase, phase-to-neutral and phase-to-earth and the actuation time for the correct dimensioning of its protection.
To calculate the short-circuit current of a system, the impedance involved from the distribution network to the equipment to be protected is taken into account.
The short circuit causes a current increase greater than the circuit was designed to withstand, therefore, every short circuit is an overload, but not every overload is a short circuit.
Protection devices
Now that we know the difference between overload and short circuit, what type of protection should I use to protect against these phenomena?
For both cases, you can use both the fuse and the circuit breaker, however, it is more recommended to use the circuit breaker for overloads as it is a thermomagnetic device and acts more quickly in these cases. The fuse has a link that breaks when an overcurrent passes through it.
It is important to highlight that there are different types of fuses and circuit breakers on the market, each having a specific protection function and suitable for protecting specific equipment. For this reason, it is very important that the sizing of a protection device is carried out by a qualified and qualified professional.
Arsan Comercio e Serviços Ltda is a company specialized in providing engineering, maintenance and electrical installation services. With more than 10 years of market experience to provide the best. If you want to know more about this work, contact our professionals.
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