18
SN odvodniki prenapetosti
MV surge arresters
2SS15N splošno
2SS15N generally
2.1 2SS15N
2.1 2SS15N
Namen
Kovinsko oksidni srednjenapetostni odvodniki
prenapetosti so namenjeni za vgradnjo v SN omrežje do
45 kV kot zaščita pred direktnim udarom strele.
Lastnosti
Vrhunsko kvaliteto jim zagotavlja:
• zmogljiv varistorski blok
• toga konstrukcija ohišja
• varistorji so neposredno zaliti s silikonom
Splošni podatki:
• Temperaturno območje T: -60 °C…+85 °C
• Material ohišja: silikon (UL 94 V-0)
• 100 % končna kontrola
• Priključni navoj: M12x20 mm
• IEC razred I
• Testirani po standardih: IEC 60099-4
IEC 60099-5
• Certifikat izdal: CESI - Italija
Opis delovanja
Varistorji iz cinkovega oksida so nelinearni upori,
pri katerih je tok odvisen od napetosti. Odvodniki z
vgrajenimi ZnO varistorji imajo veliko upornost. Ob
nastopu prenapetosti se upornost zmanjša v času 25 ns.
Zaradi tega ima odvodnik sposobnost odvajanja velikih
impulznih tokov v zelo kratkem času. Po prenehanju
prenapetosti se upornost ponovno poveča na prvotno
stanje. Odvodniki tipa 2SS15N vzdržijo najmanj 20
udarov atmosferskih praznjenj.
Izračun in izbira
Posebno pozornost je potrebno nameniti izbiri
ustreznega tipa ZnO odvodnika.
1. Podatki omrežja distributerja
• U
max
- maksimalna napetost
• t
- čas trajanja kratkega stika
• k
z
- faktor zemeljskega stika
k
z
= 1,40 - neposredno ozemljeno
k
z
= 1,40 - 1,7 z malim uporom
k
z
= 1,73 - 1,8 z izol. nevtralno točko
2. Podatki za odvodnike tipa 2SS15N
• k
0
= 0,8
• k
t
= faktor trajne obratovalne napetosti za časno
prenapetost (Diagram 1)
Usage
Metal oxide middle voltage surge arresters are designed for
installation in MV power networks up to 45 kV as protection
against direct lightning strikes.
Characteristics
The top quality is ensured with:
• top quality varistor block
• rigid construction of housing
• varistors are directly enclosed by silicone
General data:
• Temperature range T: -60 °C…+85 °C
• Housing material: silicone (UL 94 V-0)
• 100 % final control
• Connection thread: M12x20 mm
• IEC class I
• Tested according to standards: IEC 60099-4
IEC 60099-5
• Certifikate issued by: CESI - Italy
Description of activity
Zinc oxide varistors are non-linear resistors where the
current depends on voltage. Surge arresters with built-in
ZnO varistors have large resistance. When over voltage
occurs the resistance decreases in time of 25 ns. Because
of this the surge arrester has an ability of discharging
enormous pulse currents in a very short time. When over
voltage stops the resistance increases back to its primary
condition. The surge arresters type 2SS15N resist at least 20
strokes of atmospheric discharging.
Calculation and choice
It is necessary to grant special attention for the selection of
a suitable type of ZnO surge arrester.
1. Data of electric network
• U
max
- maximum voltage
• t
- duration time of short circuit
• k
z
- factor of grounding
k
z
= 1,40 - directly grounded
k
z
= 1,40 - 1,7 with little resistance
k
z
= 1,73 - 1,8 with neutral insulating spot
2. Data for surge arresters type 2SS15N
• k
0
= 0,8
• k
t
= factor of continuous operating voltage for over
voltage duration time (Diagram 1)
1
3
4
5
6
9
7
8
2
