2. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 1 LIGHTNING PROTECTION OF MEDIUM VOLTAGE OVERHEAD LINES WITH COVERED CONDUCTORS BY ANTENNA- WITH COVERED CONDUCTORS BY ANTENNA-TYPE LONG FLASHOVER ARRESTERS A ALFA

3. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 2 Lightning protection diagram 1 – thunderstorm cloud; 2 – lightning channel; 3 – space charge; 4 – pole; 5 – insulator; 6 – insulator flashover channel; 7 – binding; 8 – insulating cover; 9 – conductor’s core; 10 – surface flashover channel; 11 – piercing clamp.

4. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 3 ALFA operating principle 12 – electrode; 13 – antenna

5. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 4 Protection of MV line by ALFA 14 - insulator; 15 – steel pipe

6. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 5 Line mock -up testing

7. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 6 Equivalent circuit diagram Ul - lightning potential Uа - antenna potential Clа - lightning-antenna Cаg - antenna-ground R - leakage resistance

8. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 7 Antenna potential vs. time to breakdown

9. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 8 Simplified test outline simulation of lightning leader approaching a line U

10. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 9 Simplified test outline simulation of lightning final stroke U

11. George Podporkin Ru Session 2 – Block 1 – Paper 19 Barcelona 12-15 May 2003 10 –ALFA flashovers well before a direct contact of the channel with a conductor. –ALFA protects the line against both induced overvoltages and direct lightning strokes. –A simple design makes ALFA less expensive than conventional metal oxide arresters. CONCLUSIONS