The requirements for efficient overvoltage protection of electronic devices in low-voltage power systems

Povećana osjetljivost elektroničkih uređaja naširoko korištenih u niskonaponskim instalacijama zahtijeva odgovarajuću prenaponsku zaštitu. Zaštita opreme od potencijalnih prenapona se temelji na primjeni uređaja za zaštitu od prenapona (UZP). Najčešća situacija, posebno u stambenim zgradama, je primjena samo jednog UZP instaliranog u razdjelnom ormaru. Sveobuhvatna analiza ovakvog sustava prenaponske zaštite u širokim rasponima ovisnih parametara je provedena eksperimentalnim mjerenjima i velikim brojem simulacija. Dobiveni rezultati pokazuju da postojanje ugrađenih varistora unutar elektroničke opreme, s niskim zaštitnim naponima uzrokuje njihovo termičko uništenje zbog neadekvatne raspodjele energije prenapona između UZP i varistora. U radu su razmotreni zahtjevi za efikasnim sustavom zaštite koji neće izazvati uništenje ugrađenih varistora, i koji će pružiti odgovarajuće karakteristike prenaponske zaštite.The increasing sensitivity of electronic devices widely used in low-voltage AC systems requires an appropriate protection against voltage and current surges. Protection of the equipment against the prospective surges is based on application of surge protection devices (SPDs). Most common situation, especially in residential buildings, is application of only one SPD at distribution board. In the paper, comprehensive analysis of this type of overvoltage protection system with wide ranges of influencing parameters is performed through experimental measurements and number of simulations. Obtained results show that existence of built-in varistors within electronic devices, with low protection voltages causes their thermal destruction due to inadequate distribution of surge energy between SPD and varistors. The requirements for efficient protection system which will provide survival of built-in varistors, as well as proper overvoltage protection characteristics are described and discussed in the paper