Kryteria doboru elementów w typowych dwustopniowych układach ochrony urządzeń przed przepięciami występującymi w sieci energetycznej

Praca omawia kryteria doboru elementów w rezystorowo-warystorowych i rezystorowo-diodowych układach ochrony przepięciowe. Badania symulacyjne pokazują znaczenie elementów szeregowych dla zwiększenia parametrów zabezpieczeń, oraz ograniczenia.

---

One of the basic requirements for EMC is resistance on transient of high-energy appeared in supplying lines. The aim of this paper is specification of correct selection of mains (220V 50Hz) protection equipment. The protector provided as the second stage of a comprehensive surge voltage protection is under consideration. The limiting overvoltages acceptable in the third and second stage of a comprehensive protection (4kV, 6kV) to the level acceptable in the first stage (1.5kV) was assumed as the main criterion of construction of the circuit. The paper concerns the two-stage protector consisting of parallel elements - limiting shunt (varistors, protecting diode) and serial elements (resistors). As a typical interference impulse the surge impulse 1.2/50μs (8/20(μs) was assumed (EN 61000-4-5:1995). The mains supply voltage and its tolerance specify the breakdown voltage of applied parallel elements. The class of element depends of energy of transients. The proper selection of serial protection elements is important for receiving of high resistance on interference. A criterion of choice of parameters of protector's elements is energy dissipated in elements after the surge. The research was carried with use of the computer simulation, applying PSPICE program. The results of simulations confirm the expectations concerning the crucial role of serial elements in overvoltages protection.