The table below shows an overview of the typical minimum rated voltage Ur for the surge arrester, depending on the highest voltage Us and grounding of the system according to IEC 60099-4.
Highest voltage of system
Solidly earthed neutral system
Isolated neutral system or delta winding
Impedance earthed neutral system
Resonant earthed neutral system
Us [kV]
Ur [kV]
Ur [kV]
Ur [kV]
Ur [kV]
3.6
3
6
3
6
7.2
6
9
9
9
12
9
15
12
15
17.5
15
24
15
24
24
18
30
21
30
36
27
45
33
45
52
39
661)
45
661)
72.5
54
961)
661)
961)
1) High-voltage surge arrester
Surge arrester selection according to IEEE C62.11
The table below shows an overview of the typical minimum duty cycle voltage Ur for the surge arrester, depending on the highest line to line voltage Us and grounding of the system according to IEEE C62.11.
