VARISTOR PROTECTION AGAINST THERMAL DESTRUCTION WITH PROTECTIVE FAST DISCONNECTION SHUTDOWN

Subject of the invention is a protection device for the protection of varistors featuring a fast varistor shutdown inside the circuit which protects the varistor against destruction in the case of overheating. In practice the varistors are exposed to overvoltages originating from atmospheric discharge or excessive oscillation of the network voltage which induces major currents through the varistor, its heating and if the situation persists an overheating of the varistor which leads to their thermal destruction, explosion or fire in the vicinity, should they not be adequately protected. The protective device for the varistor with fast disconnector which includes a mechanical disconnection mechanical system with terminal contact made preferably from spring sheet metal whose disconnection time is additionally reduced by adding springs into the mechanical system located in a special enclosure attached to the varistor which it protects as a special unit integrated into the varistor circuit, and in the case of overheating the varistor separates it from the network and signalises such a condition by switching a signal contact to indicate the exceptional status of the device which is subject of the invention. The protection device with fast disconnection for the protection of the varistor is due to its technical concept as a special unit generally applicable regardless of the varistor dimensions, various nominal voltage levels, while during overheating its implementation prevents a negative impact of varistor fumes and can be applied also with special versions of varistor protection as for example with two varistors operating by connecting their back with a common varistor terminal. Predmet izuma je varovalna naprava za zaščito varistorja z lastnostjo hitrega odklopa varistorja iz tokokroga, ki ščiti varistor v primerih pregrevanja pred uničenjem. V praksi so varistorji izpostavljeni prenapetostim, ki izvirajo iz atmosferskih razbremenitev ali prekomernih nihanj omrežne napetosti, kar povzroči visoke tokov skozi varistor, njegovo segrevanje in v primerih predolgega trajanja prenapetosti pregrevanje varistorja in v kolikor niso zaščiteni pred termičnim uničenjem,njegovo eksplozijo inpožar v neposredni okolici. Varovalna naprava zazaščito varistorja s hitrim odklopom, ki vključuje odklopni mehanski sistem z priključnim kontaktom, izdelanim prednostno iz vzmetne pločevine, ki mu povečamo hitrost odklopa z dodajanjem vzmeti v odklopni mehanski sistem, nameščenim v pos