Where:
IEC 60071-3 explicitly allows that if a specific insulator type is proven by pollution testing, the creepage distance may be reduced. This is a crucial flexibility clause. Iec 60071-3
Outcome: Substation busbars were reconfigured to use longer insulator posts and increased phase spacing. Where: IEC 60071-3 explicitly allows that if a
| Standard | Focus | Difference from IEC 60071-3 | |----------|-------|-----------------------------| | IEEE Std 1313.2 (US) | Environmental factors for NESC | Uses simpler altitude correction (3% per 300 m) and pollution maps based on US regions. Less granular than IEC. | | ANSI C29 series | Insulator tests | Does not prescribe creepage; references IEC 60071-3 indirectly. | | GB/T 26218 (China) | Pollution selection | Very similar to IEC 60071-3 but with specific maps for Chinese industrial zones. | | Standard | Focus | Difference from IEC
| Aspect | IEC 60071-1 (AC) | IEC 60071-3 (HVDC station) | |--------|------------------|-----------------------------| | Principal stress | RMS AC + peak impulses | DC + polarity reversal + harmonics | | Temporary overvoltages | Earth faults, Ferranti effect | Load rejection, commutation failures | | Switching impulses | Line energization, fault clearing | Valve firing, DC line energization | | Polarity reversal | Not applicable | Critical (especially for cables) | | Clearances in air | Governed by AC peak | Governed by DC + superimposed impulse | | Altitude correction | Based on AC breakdown | Separate DC and AC corrections |