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SN odvodniki prenapetosti MV surge arresters

2.2 Razred 1 - izračun in izbira 2.2 Class 1 - calculation and selection

2.2.1 Izračun 2.2.1 Calculation

Podatki omrežja distributerja Data of electric network
• Um – maksimalna napetost • Um – maximum voltage
• t – čas trajanja kratkega stika • t – short circuit duration time
• kz – faktor zemeljskega stika • kz – factor of earthing
kz = 1,40 – neposredno ozemljeno kz = 1,40 – directly earthed
kz = 1,40 – 1,7 z malim uporom kz = 1,40 – 1,7 with little resistance
kz = 1,73 – 1,8 z izolirano nevtralno točko kz = 1,73 – 1,8 with a neutral insulated spot

Podatki odvodnikov 2SS15N Data for surge arresters type 2SS15N
• k0 = 0,8 • k0 = 0,8
• k t = faktor trajne obratovalne napetosti za časno • k t = factor of permanent operating voltage for
prenapetost. temporary over voltage duration time.

Karakteristike za tip 2SS15N Characteristics for type 2SS15N
k =f(t)
t
1,5
1,45
1,4
1,35
Legenda: 1,3 Legend:
k t
Krivulja T1: 1,25 Curve T1:
brez predhodne 1,2 without prior
energije 1,15 energy
1,1
T2 T1
Krivulja T2: 1,05 Curve T2:
100 kA, 4/10 μs 1 100 k A, 4/10 μs
predhodna energija 0,1 1 10 100 1000 10000 100000 prior energy
t(s)

Izračun Calculation
• Trajna obratovalna napetost sistema: • Continuous operating voltage of system:

[kV] [kV]

• Predhodna obratovalna napetost odvodnika: • Preliminary operating voltage of surge arrester:

[kV] [kV]

• Najvišja pričakovana časna prenapetost odvodnika: • Highest expected transient over voltage of surge arrester:

[kV] [kV]

• Trajna obratovalna napetost odvodnika: • Continuous operating voltage of surge arrester:

[kV] [kV]

2.2.2 Izbira 2.2.2 Selection

Ustrezen odvodnik prenapetosti izberemo iz tabel s We choose a suitable surge arrester from tables with data
podatki, na podlagi višje izračunane vrednosti med UC1 based on higher calculated value between UC1 and UC2
in UC2 tako, da izberemo prvo višjo trajno obratovalno so, that we choose the first higher value of permanent
napetost UC, ki je podana v tabeli. operating voltage UC specified in the table.

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