CKent
Electrical
- Aug 27, 2003
- 42
I would like to ask if anyone had personal experience in taking a power transformer (PXF) offline for a time. If there are any consequences which could be harmful to the life and efficiency of the PXF. And what could be done to maintain its integrity while offline.
I have seen a thread on "Long Time Storage of Transformers" thread238-98650 dated July 2004 but the length of time concern is about 2-3 years and even more than 10 years, which to my particular application would be too long.
We are operating a distribution utility with a primary voltage of 115 kV and secondary voltage of 34.5 kV, both L-L. We have 3 wdg PXFs with sizes ranging from 50MVA, 83 MVA to about 100MVA and 133MVA. Most of our substations have at least two to three PXFs. This was done based on previous medium/long range planning taking into consideration forecasted load growth. However, with the recent development in the electric industry in our country, much of concerns were directed towards loss cap limit. This is such a concern especially for distribution utility like us since we are forced to shoulder the excess loss above the loss cap.
Initial studies we made recently proved that in many cases, substations may well operate using one or two PXFs only, especially in off peak seasons, which is could be about 3-6 months a year. In short, there is a possibility of taking one PXF offline for a certain time of the year, say 6 months. This may be done by transferring the loads of the other PXF to the remaining PXF by closing the bus tie breaker. Now, assuming that I will have an overall loss reduction in operating one less PXF, I am concern if the PXF that would be idle (in place) for 6 months would degrade rather more than if we maintain it on-line? Should there be a concern in doing such? Are there any manufacturer's guide or warnings to go with this activity?
I have seen a thread on "Long Time Storage of Transformers" thread238-98650 dated July 2004 but the length of time concern is about 2-3 years and even more than 10 years, which to my particular application would be too long.
We are operating a distribution utility with a primary voltage of 115 kV and secondary voltage of 34.5 kV, both L-L. We have 3 wdg PXFs with sizes ranging from 50MVA, 83 MVA to about 100MVA and 133MVA. Most of our substations have at least two to three PXFs. This was done based on previous medium/long range planning taking into consideration forecasted load growth. However, with the recent development in the electric industry in our country, much of concerns were directed towards loss cap limit. This is such a concern especially for distribution utility like us since we are forced to shoulder the excess loss above the loss cap.
Initial studies we made recently proved that in many cases, substations may well operate using one or two PXFs only, especially in off peak seasons, which is could be about 3-6 months a year. In short, there is a possibility of taking one PXF offline for a certain time of the year, say 6 months. This may be done by transferring the loads of the other PXF to the remaining PXF by closing the bus tie breaker. Now, assuming that I will have an overall loss reduction in operating one less PXF, I am concern if the PXF that would be idle (in place) for 6 months would degrade rather more than if we maintain it on-line? Should there be a concern in doing such? Are there any manufacturer's guide or warnings to go with this activity?
