- #1
idp
- 6
- 0
I live in a highly corrosive coastal environment, a major problem we have is rusting of all components of our power transformers. I have investigated the use of 3CR12 (or equivalent) for the main tank (between 31,5MVA up to 63 MVA 132kV/22 or 11kV) (YyN0) in order to prevent rust problems.
It seems from my web reading that 3CR12 steel would be suitable for the main tank in terms of welding (ie construction) of the tank and general strength vs mild steel. (Although I don't know of any manufacturers using it in large power transformers)
My question however concerns the magnetic resistance of 3CR12 vs that of mild steel. During a phase to Earth fault, the magnetic flux in the core of the faulted phase is >>> than the other two healthy phases, the only path for this flux (as I understand it) is through the main tank of the transformer. Using mild steel for the tank, it is accepted that the magnetic resistance is low enough not to impede the flux path and thus allows for the Earth fault current return via the neutral. Does anyone have any idea of the impact of the slightly higher magnetic resistance of 3CR12 steel would have on the ability to act as the flux path during these fault conditions? IE, would the Earth fault (specifically high resistance Earth faults) still be able to be picked up by the neutral CT?https://drive.google.com/file/d/0B4jv0YTGHYuoMWh5am5fenpLUTNXek9lclhUUEtGZlRmVWNF/view?usp=sharing
Thanks for any response
It seems from my web reading that 3CR12 steel would be suitable for the main tank in terms of welding (ie construction) of the tank and general strength vs mild steel. (Although I don't know of any manufacturers using it in large power transformers)
My question however concerns the magnetic resistance of 3CR12 vs that of mild steel. During a phase to Earth fault, the magnetic flux in the core of the faulted phase is >>> than the other two healthy phases, the only path for this flux (as I understand it) is through the main tank of the transformer. Using mild steel for the tank, it is accepted that the magnetic resistance is low enough not to impede the flux path and thus allows for the Earth fault current return via the neutral. Does anyone have any idea of the impact of the slightly higher magnetic resistance of 3CR12 steel would have on the ability to act as the flux path during these fault conditions? IE, would the Earth fault (specifically high resistance Earth faults) still be able to be picked up by the neutral CT?https://drive.google.com/file/d/0B4jv0YTGHYuoMWh5am5fenpLUTNXek9lclhUUEtGZlRmVWNF/view?usp=sharing
Thanks for any response
