MBfreak
MEMBER EMERITUS
Some input from lightning protection in outdoor HV switchgear ( ie > 145 kv up to 1250 kV AC and DC) .
Power lines not included
Stage 1
Umbrella wires ( steel wires dia 45 mm) around 6 meters above the highest HV part. At least 4 meters outside the switchgear foot print.
Stage 2
Incoming HV line earth conductor solidly earthed in at least the last three pylons.
Stage 3
Hanging surge arrestors in the last HV pylon b4 switchgear
Stage 4
Surge arrestor on incoming lines in the HV Switchgear
Stage 5
185 sqmm copper nework buried in quad pattern 2,2 m, 1 m down and all concrete rebars connected to that
Stage 6
Surge arrestors as close as possible to all capacitor banks, reactors and power transformers.
Stage 7
NO phase to phase surge arrestors.
Stage 8
Building for control , protection, aux pwr xfs , communication designed as a Farady cage.
This usually works very well.
Have seen only two calamities over 35 years, both in Iran. South west half desert
So strong and often recurring surges that even very high powered modern arrestors ( 60 kA/ 90 kJ)
overheated , exploded and power transformers and CVTs died on the next heavy strike.
Ola
Power lines not included
Stage 1
Umbrella wires ( steel wires dia 45 mm) around 6 meters above the highest HV part. At least 4 meters outside the switchgear foot print.
Stage 2
Incoming HV line earth conductor solidly earthed in at least the last three pylons.
Stage 3
Hanging surge arrestors in the last HV pylon b4 switchgear
Stage 4
Surge arrestor on incoming lines in the HV Switchgear
Stage 5
185 sqmm copper nework buried in quad pattern 2,2 m, 1 m down and all concrete rebars connected to that
Stage 6
Surge arrestors as close as possible to all capacitor banks, reactors and power transformers.
Stage 7
NO phase to phase surge arrestors.
Stage 8
Building for control , protection, aux pwr xfs , communication designed as a Farady cage.
This usually works very well.
Have seen only two calamities over 35 years, both in Iran. South west half desert
So strong and often recurring surges that even very high powered modern arrestors ( 60 kA/ 90 kJ)
overheated , exploded and power transformers and CVTs died on the next heavy strike.
Ola


