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Surge arrester selection according to IEC 60099-4The 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 |
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Us [kV] | Ur [kV] | Ur [kV] | Ur [kV] | Ur [kV] |
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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 C62.11The 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. System L-L voltage | Four-wire multi-grounded neutral wye | Three-wire low impedance neutral circuit | Three-wire high impedance neutral circuit |
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Us [kV] | Ur [kV] | Ur [kV] | Ur [kV] |
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4.16 | 3 | 6 | 6 | 6.9 | - | - | 9 | 8.3 | 6 | 9 | - | 12 | 9 | 12 | - | 12.47 | 9 or 10 | 15 | - | 13.8 | 10 or 12 | 15 | 18 | 22.86 | 15 | 21 | - | 23 | - | - | 30 | 34.5 | 27 | 36 | - |
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