LarrylLix said:Not quite a good diagnosis. Lightning jumping from one winding into another winding across the winding insulation is not due to any lack of grounding.
Distribution transformers may occasionally have lightning protection installed at it's primary bushings to prevent lightning surges from breaking down internal insulation but a direct hit from lightning is not stopped by lightning arresters or interwinding insulation. Most of the equipment explodes from the millions of joules and/or voltage avalaible due to the lightning hit.
So you are saying engineers who did the analysis lied? Or that California lightning does not cause catastrophic damage? Why do you believe anything inside a transformer will stop what three miles of sky cannot? Nobody except you said anything about 'stopping' lightning. Any protector that would do that is blown through. So transformers have an earth ground. Why are you arguing against what has been well understood and standard procedure for generations?
Why would insulation between 'primary' (ie 33,000 volts) and 'secondary (ie 240 volts) not breakdown? Because a transformer is properly earthed. Then hundreds of thousands (not millions as you only assumed) of joules dissipate harmlessly in earth.
Insulators also remain insulators IF proven protection is not compromised. No surge need break down insulation. Direct lightning strikes to AC power equipment is routine without damage. But only if that protection path is connected to earth.
Engineers said why that transformer exploded. Engineers said that transformer failure would not happen if a ground wire existed. Why do you know they are wrong? Especially when they said what we have long understood. Direct lightning strikes do not damage properly earthed transformers. Then even California lightning does not create plasma that shorts 33,000 volts into a 240 volt service.
All utility equipment has protection either inside or attached. In every case, that protection is earthed. Even California can have direct lightning strikes that cause significant damage - when a critical earth ground is missing. Reality does not change because you were not there.
Reclosers do nothing for protection. As made obvious by numbers. Lightning is done in microseconds. Reclosers operate in milliseconds or seconds. How does a centimeters gap in a recloser avert or block what three miles of sky could not? Obviously it does not. It does not do protection. It only attempts to restore service after lightning and its plasma has dissipated.
Recloser attempts to restore service hoping damage does not exist or has been isolated by fuses. Your numbers make it obvious - recloser could never do lightning protection. If earth ground for a transformer has successfully protected transformer's secondary to primary volt insulation, then a recloser can restore service. Routine is a direct strike incoming to a transformer without damage - if that transformer earth ground exists.
But that ground did not exist in California. So lightning shorted 33,000 volts to 240 volt service. Lightning did not explode that transformer into tiny pieces. A follow through current from 33,000 volt service was shorted by a lightning compromised transformer - that was missing its earth ground. Engineers who did the analysis said so. Even California can suffer significant damage from lightning.
Why claim what happened did not happen? Even California with less lightning needs that protection.