19
SN odvodniki prenapetosti
MV surge arresters
2SS15N splošno
2SS15N generally
Legend
Curve T1:
without preliminary energy.
Curve T2:
100 kA, 4/10 µs
preliminary energy.
Legenda
Krivulja T1:
brez predhodne
energije.
Krivulja T2:
100 kA, 4/10 µs
predhodna energija.
Karakteristike /
Characteristics
1,5
1,45
1,35
1,3
1,25
1,2
1,15
1,1
1
0,11
10
100
1000
10000
1000000
t(s)
k
t
T1
T2
k
t
=f(t)
1,4
1,05
Diagram 1 /
Diagram 1
3. Izračun in izbira
• Trajna obratovalna napetost sistema:
[kV]
• Predhodna obratovalna napetost odvodnika:
[kV]
• Najvišja pričakovana časna prenapetost odvodnika:
[kV]
• Trajna obratovalna napetost odvodnika:
[kV]
Ustrezen odvodnik prenapetosti izberemo iz tabel s
podatki na podlagi višje izračunane vrednosti med U
C1
in U
C2
tako, da izberemo prvo višjo trajno obratovalno
napetost U
C
, ki je podana v tabeli.
3. Calculation and choice
• Continuous operating voltage of system:
[kV]
• Preliminary operating voltage of surge arrester:
[kV]
• Highest expected transient over voltage of surge arrester:
[kV]
• Continuous operating voltage of surge arrester:
[kV]
We choose a suitable surge arrester from the tables with
data based on higher calculated value between U
C1
and U
C2
.
Therefore we choose the first higher value of continuous
operating voltage U
C
, which is offered in the table.
Izračun zaščitne razdalje
1. Podatki omrežja distributerja
Stopnja zaščite naprav na daljnovodih je odvisna
od razdalje med ščiteno napravo in odvodnikom.
Prenapetostni odvodnik ščiti v določeni razdalji od
mesta, kjer je montiran. Za izračun so potrebni najmanj
naslednji podatki.
• l
z
- zaščitna razdalja odvodnika
• U
z
- zdržna udarna napetost izolacije opreme
• U
res
- maksimalna vrednost preostale napetosti za
določen tip odvodnika
• v
- hitrost širjenja udarnega vala
po vodih
v
= 300 m/μs - nadzemni vod
v
= 150 m/μs - kabel
Calculation of shielding distance
1. Data of electric network
Level of protection for devices on power lines depends on
the distance between the protected device and the surge
arrester. The surge arrester protects in a certain distance
from the spot where it is mounted. For the calculation, there
are at least the next data necessary.
• l
z
- shielding distance of the surge arrester
• U
z
- allowed trigger voltage of insulating equipment
• U
res
- maximum value of residual voltage for the
chosen type of surge arrester
• v - speed of shock wave spreading through electric
wires
v = 300 m/μs - overhead wire
v = 150 m/μs - cable
2
1
3
4
5
6
9
8
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