When lightning hits an installation, high impulse currents and impulse voltages appear within conductive systems, which can be compared to an enormous tsunami.
If this tsunami is not broken, important electrical equipment will be destroyed. The lightning tsunami is similar to an impulse current reaching its peak value within only 10 millionths of a second, and reducing its value again by 50% within 350 millionths of a second. In order to control this lightning force successfully, a specified lightning and surge protection concept is necessary.
Safe lightning and surge protection is based on the Lightning Protection Zones (LPZ) concept described in IEC 62305-4. The relevant principle is that the object to be protected is divided into protection zones. This principle can be applied to protect a detached house as well as a large-scale installation.
The protection zones are divided up, firstly from the outside area of the object to be protected, and thereafter in the inside area. Surge arresters are installed at the boundaries of the different protection zones. The DEHN + S"OHNE Red/Line product range provides the correct surge protection devices for every type of installation.
The first protective stage LPZ 0A -1 requires a 'wave breaker' to discharge the majority of the lightning current. The surge protection device used for this stage is therefore also called a lightning current arrester.
Such impulse energies can be controlled safely by spark gaps only, as these 'switch' the lightning impulse current wave and therefore reduce the pulse time. The function of the subsequent protective stages is to discharge the residual impulse currents of the lightning flood wave and to reduce the surges induced by the electromagnetic field to a bearable level for downstream equipment.
According to the application, the DEHN 'wave breakers' are designed as combined lightning current and surge arresters, co-ordinated lightning current arresters and lightning current arresters. By using the DEHNventil, DEHNbloc Maxi and DEHNbloc product ranges, the user finds the correct solution for every type of installation.
DEHN's modular Red/Line multipole DEHNventil M combined lightning current and surge arresters are designed for protecting low voltage installations and terminal devices against surges, even during direct lightning strikes.
The devices are used according to the lightning protection zones concept at boundaries 0A - 2.
The all-in-one Type 1 modules are pre-wired, combining spark-gap-based lightning current and surge arresters consisting of a base part and plug-in protection module. They provide maximum system availability due to their RADAX Flow follow-on current limitation. The devices have a discharge capacity up to 100kA (10/350 us) and there is no tripping of 32A gL/gG fuses up to short-circuit currents of 50kArms.
By using encapsulated creepage discharge spark gaps, combined with their compact design, makes DEHNventil M units ideal for use in switchgear installations and distribution boards. The surge arresters can be connected in series up to nominal currents of 125A as per IEC 60364-5-53.
The DEHNventil M units are easily exchanged by simply pressing the module release button, and the user can see the operating state/fault indication by a mark in the inspection window. A new innovation is the monitoring of the neutral module, which is a requirement for maintenance purposes.
DEHN's DEHNbloc Maxi Class 1 lightning current arresters are designed to reliably protect LV installations against surges, even with direct lightning strikes. The devices are used at the LPZ 0A - 1 boundary, and with their high insulation resistance, they can be installed upstream of the supply metre.
Due to DEHNbloc Maxi's unique encapsulated technology, special safety distances from busbars or other equipment are not required by the arresters and no special flameproof enclosures are necessary. With a discharge capacity of 50kA (10/350) per pole, the DB 1 arresters fulfil the highest requirements of international lightning protection standards.
The unique design allows simple energy co-ordination with downstream surge protective devices in DEHN's Red/Line family, without the need for additional cable lengths or decoupling coils. The leakage current-free spark gap-based arresters are robust in design and are housed in red thermoplastic to UL 94 V-O.
DEHNbloc H lightning current arresters have successfully provided maximum protection between LPZ 0A - 1 for many years. The device replaces the approved pressure-controlled encapsulated creepage discharge spark gap by a modern Radax-Flow spark gap.
While single or two-stage protection concepts are designed for small sized electrical installations, a three-stage protection concept has proven to be an economical and technical optimum for medium-sized and major installations.
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