For DC withstand: ( U_cw,DC = 630 \times 1.10 = 693 , \textkV ) → ( U_rw,DC = 693 \times 1.10 \approx 762 , \textkV ). Standard DC test voltage = 750 kV (1 min).
Standard LIWV from IEC 60071-3 for ±500 kV: choose 1050 kV (closest standard value). Iec 60071-3
Assume ( k_sa = 1.10 ) (indoor valve hall) → ( U_rw = 920 \times 1.10 = 1012 , \textkV ) For DC withstand: ( U_cw,DC = 630 \times 1
| Term | Symbol | Description | |-------|--------|-------------| | Direct voltage (steady state) | ( U_d ) | Average DC voltage under normal operation. | | Direct voltage (no-load) | ( U_d0 ) | Ideal no-load DC voltage. | | Continuous operating voltage | ( U_C ) | Maximum steady-state DC voltage (including tolerances). | | Temporary overvoltage (TOV) | ( U_TOV ) | DC overvoltage of limited duration (e.g., load rejection, filter detuning). | | Slow-front overvoltage (SFO) | ( U_SFO ) | Impulse with time to peak ( T_p > 20 \mu s ), e.g., energization of DC line. | | Fast-front overvoltage (FFO) | ( U_FFO ) | Impulse with ( 0.1 \mu s < T_p < 20 \mu s ), e.g., valve firing. | | Polarity reversal voltage | ( U_pr ) | Voltage change from positive to negative or vice versa (critical for cable insulation). | Assume ( k_sa = 1
Insulation Co-ordination for HVDC Converter Stations: A Comprehensive Review of IEC 60071-3
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