How to ground surge protective device

- Aug 18, 2020-

As we all know, thunderstorm weather lightning impact and damage is very huge, so for a variety of power supply electrical equipment, do the corresponding lightning protection measures is also very important. With the continuous progress of modern lightning protection technology, lightning protection products are constantly bringing forth new ones. As a professional lightning protection device, surge protective device (SPD) has attracted the attention of many users in recent years.

Surge protective device (SPD), also known as lightning protection device, is an electronic device that provides security protection for various electronic equipment, instruments and communication lines. When the electric circuit or communication line suddenly produces peak current or voltage due to external interference, the surge protective device (SPD) can conduct and shunt in a very short time, so as to avoid the damage of surge to other equipment in the circuit. It is suitable for the requirements of surge protection in home, tertiary industry and industrial fields.


However, in thunderstorm weather, it is not enough to install surge protective device (SPD) to protect electronic equipment. More importantly, outdoor surge protective device (SPD) should be grounded in a standard way, because the surge protective device (SPD) will become a conductor and lead the induced current into the earth when lightning strikes. Therefore, if there is no grounding system ground wire or no standard grounding, the surge protective device (SPD) will lose its function.

So how to standardize the installation and grounding?

First of all, we must carefully survey the site conditions, and after careful planning, according to the size of the equipment and the incoming line position of the power supply bar, we should plan out enough space and arrange the position. Surge protective devices at all levels of power lines shall be installed at the entrance of the line entering the building, the interface of lightning protection area and near the protected equipment. During installation, the power should be cut off to prevent electric shock.

The installation of power surge protective device (SPD) is mainly to discharge a large amount of lightning and surge current and limit the surge voltage. Because the surge current is very large, the nominal discharge current and maximum discharge current of SPD are also large, so the cross-sectional area of the upper and lower leads should be certain. According to the different SPD series, the requirements of conductor cross-sectional area are also different. Generally speaking, the SPD grounding terminal of signal line surge protective device (SPD) should be connected with the local equipotential grounding terminal board in the equipment room with a cross-sectional area of not less than 4mm2, which can reduce the lead inductance, thus reducing its dynamic impedance and reducing the line residual voltage.

In addition, according to "technical code for lightning protection of building electronic information system", the installation of signal line surge protective device (SPD) shall comply with the following provisions: SPD of signal line shall be connected to the signal port of protected equipment. SPD output terminal of SPD is connected with the port of protected equipment.

It can be seen that surge protective device (SPD) has high technical requirements in installation and grounding. Only when it is installed in accordance with professional regulations and standards, can surge protective device (SPD) play its greatest role.