ELECTRICAL SUPPLY SYSTEM PROTECTION: SURGE PROTECTION DEVICES FOR RESIDENTIAL, COMMERCIAL AND INDUSTRIAL APPLICATIONS

For the optimal protection of electrical systems, and in addition to the use of differential, magnetic and thermal overload devices, it is important to protect the installation with SPDs (Surge Protection Devices) a.k.a. surge arresters.

These components, situated inside the main and/or secondary switchboards are designed to protect equipment, systems and assets within the building from over-voltages caused by direct current,  circuit-breaker (switching) activity or voltages induced by lightning during thunderstorms.

The choice of the device to be installed must follow the relevant regulations such as CEI 81-10 for the sizing of complete lightning protection systems and, CEI 64-8 covering the design and installation aspects of protection systems within domestic, commercial and industrial electrical systems. In addition to specifying the installation of SPDs, these standards differentiate between the types of SPD – classifying them as:

• Type 1 SPDs, which can be installed inside an electrical panel to ensure the protection of people and systems from currents caused by lightning introduced into buildings through overhead power lines or installed lightning rods.
• Type 2 SPDs, which can be installed in secondary switchboards to protect systems and equipment from induced and switching over-voltages.
• Type 3 SPDs feature small dimensions that allow installation within 503 boxes or in electrical panels for the protection of sensitive electronic equipment such as TVs, boilers, modems, Hi-Fis, refrigerators or dishwashers.

For a clear understanding of the product, it should be borne in mind that SPDs are also characterised by their design technology. Specifically, there are:

• Switching SPDs, in which the management of the over-voltage is entrusted to a spark gap or to the more modern GDT. This type of arrester is recognized for its high galvanic isolation and high discharge current capability.
• Voltage limiting SPDs, where a varistor used in the device intervenes for the duration of the over-voltage by clamping the voltage locally to a constant and low value ​​that typically can be tolerated by the downstream equipment.

Additional to the above are products classified as Type 1+2. These devices offer the combined benefits of both Type 1 and Type 2 SPDs, boasting high galvanic isolation, an absence of follow-on current or leakage current and a high discharge capacity.

Finder’s wide range of SPDs ensures protection against direct, induced and switching over-voltages and can be summarised as:

• Type 1+2 surge arresters with high discharge capacity, no follow-on current and no leakage current for single-phase/three-phase applications (230/400 V AC) with lightning currents up to 100 kA: Types 7P.02, 7P. 03, 7P.04 and 7P.05.
• Type 1+2 surge arresters for quick mounting on the distribution bars of three-phase TT and TN systems (230/400 V AC) without follow-on current and no leakage current: Types 7P.03.8.255.Sx07, 7P.03.8.255 .Sx12, 7P.04.8.255.Sx07 and 7P.04.8.255.Sx12.
• Type 1+2 surge arresters with low Up value for single-phase/three-phase applications: Types 7P.12, 7P.13, 7P.14 and 7P.15.
• Type 2 surge arresters for single-phase or three-phase systems with cartridge restraint system: Types 7P.21, 7P.22, 7P.23, 7P.24, 7P.25 and 7P.27
• Type 2 surge arresters without leakage current for single-phase or three-phase AC systems. Reference types 7P.42, 7P.43, 7P.44 and 7P.45.
• Surge arresters for photovoltaic applications. For Type 2 devices, refer to Type 7P.23.9; for Type 1+2 refer to Type 7P.03.
• Type 3 surge arresters suitable for single-phase applications for recessed installation (503 boxes) and for DIN rail Types 7P.31, 7P.32, 7P.36 and 7P.37
• Type 2+3 surge arresters for the protection of 2-wire signal and data transmission lines Types 7P.62 and Ethernet with Type 7P.68.

FOR FURTHER INFORMATION ON FINDER SPDs FOR RESIDENTIAL, COMMERCIAL AND INDUSTRIAL APPLICATIONS, DOWNLOAD THE GUIDE HERE.

In accordance with the new edition of CEI 64-8, the installation of surge protection devices is mandatory in cases where the effects of the surge can cause injury to persons, or damage to property and public buildings. It is also mandatory to install one or more SPDs in places close to commercial activities and in all public areas with constant occupation.

In this context, installing products from the Finder range will ensure that this mandatory protection is met and, according to the SPD Type and application, may contribute other beneficial characteristics, such as:

• Type 1 SPDs with varistor and GDT in series ensure galvanic isolation between phases and zero leakage current.
• Type 1 SPDs with low residual voltage (Up) ensure effective protection starting from the energy delivery point.
• From Type 1 and Type 2 devices with their replaceable cartridge restraint systems to Type 3 SPDs protecting LED lamps, sensitive electronics and data lines, this is a range that is well recognized for being feature rich and versatile over a wide range of applications.

And finally, all Finder SPDs equipped with replaceable cartridges have remote fault signalling contacts either as standard or as an option.

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