Abstract
This paper presents the results of experimental studies of voltage phenomena in the switching operations of vacuum switching devices made by various manufacturers in several different configurations of 6 kV, 10 kV, 20 kV and 35 kV networks. During switching-on operations of the inductive loads, re-ignition of the electric arc between the contacts of the vacuum switching devices appears. Each arc ignition appearance leads to overvoltages with gradients close to those of lightning overvoltages. Switching-off operations of the inductive loads with vacuum switching devices leads to the cutting of the current before it passed through a natural zero and the appearance of multiple re-ignition of the arc between their contacts. All this leads to significant overvoltages on the equipment insulation. The analysis of surges in the studied networks, and the measures and means to reduce the stress of isolation are proposed.
Highlights
Iako su im pri uključenjima strmine bliske strminama atmosferskih prenapona, niže su od 170 kV/ s, i ne bi trebalo da predstavljaju opasnost za međunavojnu izolaciju 35 kV namotaja transformatora 35kV/10kV pod uslovom da nije došlo do degradacije njihove izolacije tokom eksploatacije
[4] Petar Vukelja, Jovan Mrvić, Dejan Hrvić, 2007, "Overvoltages at vacuum switching devices operation",CIGRE, "Transient Phenomena in Large Electric Power Systems",Symposium [18-21], Zagreb, 2007, Croatia
Summary
Pri uključenjima neopterećenih transformatora 35kV/10kV, 35kV/20kV i 20kV/6kV, kablovskih ili nadzemno kablovskih vodova sa neopterećenim transformatorima 20kV/0,4kV, 10kV/0,4kV, 6kV/0,4kV i motorima 6 kV vakuumskim prekidačima dolazi do višestrukih prethodnih paljenja električnog luka između kontakta njihovih polova (slike 1 i 2). Najviši prenapon koji se pojavio pri 8 izvedenih uključenja (16 članova uzorka prenapona) je [3,34] p.u. Uključenja neopterećenih kablovskih i nadzemno-kablovskih vodova 20 kV i 10 kV ne dovode do pojave prethodnih paljenja električnog luka između kontakta polova vakumskog prekidača. Razlog je što je na kablovskim vodovima prisutan zaostali napon, jer se u tako kratkom periodu vremena ne mogu potpuno rasteretiti
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