What is the configuration of HV to LV transformers? The LV side is obviously star, but what about the HV? Is it star or delta? As there is no neutral on HV, I had kind of assumed it would be delta, derived from a star at the 33KV substation.
If a single HV phase goes down, leaving two working, what's the effect of the LV?
Quite often your lights go dim rather than off during a power failure, and I assumed this was one HV phase going down on a DELTA-STAR TX. One one winding is receiving full volts, the other two ending up in series because of the lost phase, in series cause lower volts on two of the LV phases.
The other day though, a site fed from its own pole mounted TX lost an LV phase completely, and it turned out the farmer had pulled down one HV phase quite close to the TX. I assume that must be a STAR-STAR TX? Can't see how loosing one HV phase would cause one LV phase to drop otherwise?
Farmer hadn't even realised he had taken out the line.
If a single HV phase goes down, leaving two working, what's the effect of the LV?
Quite often your lights go dim rather than off during a power failure, and I assumed this was one HV phase going down on a DELTA-STAR TX. One one winding is receiving full volts, the other two ending up in series because of the lost phase, in series cause lower volts on two of the LV phases.
The other day though, a site fed from its own pole mounted TX lost an LV phase completely, and it turned out the farmer had pulled down one HV phase quite close to the TX. I assume that must be a STAR-STAR TX? Can't see how loosing one HV phase would cause one LV phase to drop otherwise?
Farmer hadn't even realised he had taken out the line.