Lightning protection guide by OBO

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Last revision 2020

Vydal: OBO BETTERMANN s. r. o. Autor: OBO BETTERMANN

Strana 229 z 288

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TN-C net- works, severe interference can also occur the data cable. the losses are too great, certain transmission standards will longer complied with. Device 1 Device 2 Data cable Direct connection earth Indirect connection earth Gas-discharge table Equipotential busbar Earthing cable Indirect earth one side TBS Blitzschutz-Leitfaden 2018 / en / 2020/01/10 14:42:40 14:42:40 (LLExport_02613) / 2020/01/10 14:42:54 14:42:54 229 Chapter The internal lightning protection system . case interventions the cable, for ex- ample the integration connection sockets, plugs and adapters, even the bending radius too small, can safely assumed that signal losses will occur.5 Transmission characteristics Due their sensitive signal levels, data cables are particularly susceptible interference. This happens when the earth res- istance different different earthing systems, thus creating potential difference. Because the gas-discharge protector has resistance several gigaohms, there is direct connection between the individual earthing systems. This en- sures that the shield not exposed the full current at just one end. The connection the other end has low resistance, leads directly the equipotential bonding, the lightning current or surge voltage can arrested both ends. The high impedance one end prevents equalising currents from flowing. Data cable with indirect earth one side One way avoiding equalising currents earthing the shield indirectly one end. This can lead to connection errors complete interruption the signal. This done con- necting the shield the equipotential bonding via a gas-discharge protector. the two systems are connected via the shield, the equalising currents at- tempt eliminate the potential difference.3. The larger the difference potential, the greater the equalising currents.1.TBS Blitzschutz-Leitfaden 2018 / en / 2020/01/10 14:42:40 14:42:40 (LLExport_02613) / 2020/01/10 14:42:54 14:42:54 Cable shields minimise interference conducting away the currents from the parasitic capacitances. the current too great and the shield can- not withstand it, cable fires can occur. Equalising currents are, however, still able flow through the shield. The integ- ration surge protection devices also counts an intervention the cable. 3. If the shield impacted lightning, the gas-dis- charge protector ignites