DEVICE FOR PROTECTION AGAINST OVERVOLTAGE AND NULL MONITORING

The invention relates to a device for protection against overvoltage and for monitoring the null, meant for protecting the mains supplying the domestic subscribers, connected to the electrical network. According to the invention, the device consists of an electronic circuit (A) connected, by means of some conductors, to some terminals (1, 2, 3 and 4) of a magnetic-thermal and differential service line circuit breaker (B) and to the ground terminal (5). The electronic circuit (A) comprises a supply unit (BA), an overvoltage sensing unit (BST), a summation unit (BS), a phase change unit (BSF), a return voltage unit (BTI), an execution and triggering unit (BED), a signalling and resetting unit (BSR). The connection module thereof provides the protection of the domestic subscriber power mains to industrial frequency overvoltages, to the effects of breaking the null from the power mains or from the domestic subscriber line as well as the protection of the power supplier against fraudulent attempts to steal electric energy and the optical signalling of the activation of all these protections. The subscriber disconnecting and the signalling of the failure status is also maintained after the elimination of the failure causes, until the operator takes knowledge of the existence of a previous failure condition and resets the system. Invenţia se referă la un dispozitiv de protecţie la supratensiune şi monitorizare a nulului, destinat protecţiei coloanei generale de alimentare a abonaţilor casnici, branşaţi la reţeaua electrică de transport a energiei electrice. Dispozitivul conform invenţiei constă dintr-un circuit electronic (A), conectat prin intermediul unor conductori, la nişte borne (1, 2, 3 şi 4) ale unui întrerupător de branşament (B) de tip magnetotermic şi diferenţial şi la borna (5) de pământ. Circuitul electronic (A) este compus dintr-un bloc de alimentare (BA), un bloc de sesizare a supratensiunii (BST), bloc sumator (BS), un bloc de schimbare fază (BSF), un bloc al tensiunilor de întoarcere (BTI), un bloc de execuţie şi declanşare (BED), un bloc de semnalizare şi resetare (BSR). Modulul de conectare al acestora asigură protecţia coloanei electrice a abonatului casnic la supratensiuni de frecvenţă industrială, a efectelor ruperii nulului din reţeaua electrică de transport a energiei electrice sau din coloana de abonat casnic, cât şi la protecţia furnizorului de energie electrică împotriva încercărilor frauduloase de sustragere a energiei electrice şi semn