1George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

LIGHTNING PROTECTION OF MEDIUM VOLTAGE OVERHEAD LINES

• WITH COVERED CONDUCTORS BY ANTENNA-WITH COVERED CONDUCTORS BY

ANTENNA-TYPE LONG FLASHOVER ARRESTERS A

ALFA

2George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

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.

3George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

ALFA operating principle

12 – electrode; 13 – antenna

4George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

Protection of MV line by ALFA

14 - insulator; 15 – steel pipe

5George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

Line mock -up testing

6George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

Equivalent circuit diagram

Ul - lightning potential Uа - antenna potential

Clа - lightning-antenna Cаg - antenna-ground

R - leakage resistance

7George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

Antenna potential vs. time to breakdown

8George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

Simplified test outline

simulation of lightning leader approaching a line

U

9George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

Simplified test outline

simulation of lightning final stroke

U

10George Podporkin Ru Session 2 – Block 1 – Paper 19

Barcelona 12-15 May 2003

– 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