Brazil is the country that has the highest incidence of lightning in the world, offering great risks, both for people and for the electrical and electronic equipment that are in the facilities. Due to the many doubts surrounding this phenomenon of nature and the protection methods used, we decided to explain what lightning, lightning, lightning and SPDA are, in addition to talking about the application of SPDA in conjunction with DPS, come on a person!
Lightning and lightning: What are they?
Lightning strikes are natural and unpredictable phenomena and there is still much to be studied on the topic, lightning strikes are nothing more than what we know as lightning strikes, lightning strikes are defined as lightning strikes of atmospheric origin, which normally occurs between the cloud and the earth.
The rays appear basically because there is a big difference in negative and positive charges between the clouds and the earth respectively, there is a big difference in charges, there is a very strong attractive force between them that end up breaking the air resistance and meeting, or that is, an atmospheric discharge occurs.
Lightning strikes occur in a fraction of a second and are capable of reaching extremely high temperature, current and voltage values, causing various damages to people and electrical and electronic equipment, even if these discharges have arrived directly or indirectly at installations or yet the point of impact of the beam was at a certain distance the person is located.
Lightning and lightning: Protections!
There are devices that are capable of protecting electrical installations against this phenomenon of nature, which is DPS and SPDA. So that the combination of both protection features ends up generating doubts for some professionals in the area.
The first tip is about the obligation to install DPS even when an SPDA is already installed in the building.
The first tip to know about the combination of both protection features is to understand what SPD and DPS are, where they are installed and what are their characteristics and their respective functions! After that, it is easy to understand the need to install both overvoltage and lightning protection.
SPDA: What is it?
SPDA stands for the lightning protection system, which many know as a lightning rod. The SPDA is used on the outside of buildings, to prevent fires and other damage that may be caused due to the direct impact of lightning on the building.
The SPDA provides a path of least resistance possible for the high electrical current of the lightning to flow towards the earth, without damaging equipment or structures, in addition to protecting people inside the facility. the dangerous electric current of an atmospheric discharge, minimizing or canceling its impacts
DPS: what is it?
DPS stands for surge protection device, where the main function is to drain the overvoltage caused by lightning and limit this overvoltage, so as not to damage the electrical and electronic equipment contained in the installations.
It is important to note that overvoltage does not occur in electrical installations, that is, it only happens with lightning and other phenomena such as the start of large motors.
There are three classes of surge protection devices, which are classes I, II and III. But, it is important to understand that these classes cannot be compared with each other, because each class has a particularity and a specific application.
One of the main factors that differentiate the classes of DPS is the capacity and the speed of flow of the overvoltage, acting in the protection against lightning strikes directly, which is when the lightning strikes the installation itself, or indirectly, which is when the lightning strikes the distribution network.
SPDA and DPS working together?
Now that we know what SPDA, DPS, their characteristics and applications are, we can conclude that DPS and SPDA can protect installations against lightning strikes, only one of these two protection methods is needed to protect the electrical installation against lightning strikes, correct ?
In fact it is not quite like that! It is wrong to say this, because as we have already seen, the DPS and SPDA serve different purposes.
DPS and SPDA: What does the standard say?
According to the NBR 5410 standard, when the objective is protection against atmospheric overvoltages transmitted by the external power line, such as protection against switching overvoltages, the DPS must be installed close to the line entry point in the building or in the building. main switchboard, located as close as possible to the entry point.
However, when the objective is protection against overvoltages caused by direct lightning strikes on or near the building, the DPS must be installed at the entry point of the line in the building.
The NBR 5410 standard requires the installation of protection devices in an installation such as, for example, IDR and DPS in the distribution boards, regardless of which installation.
But, the best way to find out which class of protection devices is correct to be used in buildings with the SPDA system is by consulting the NBR 5419 standard, which is the specific standard on lightning discharges.
SPDA: where and how to use it?
You may not know it, but many buildings do not require protection against direct lightning strikes on the building’s structure or entry lines, ie DPS class I, but the standard requires at least the installation of class II DPS in buildings.
When SPDA exists in the building, DPS class I must be installed for direct effects and DPS class II for indirect effects. However, when there are very sensitive equipment in the installation, it is advisable to install a class III DPS in that particular outlet.
For this protection to occur efficiently, the DPS must comply with the standards and be selected according to the indications of NBR 5410, which highlights the level of protection, maximum continuous operating voltage, as long as the device supports the short-circuit current. circuit, in addition to the rated discharge current and impulse current.
There are other factors and characteristics of the DPS that must be analyzed before being installed, so we put this complete video below explaining in extremely simple detail how to choose the correct DPS for each installation.
We finish one more article here and we hope to have