Kelly had a low-level nitrogen leak in a transformer that required a new bottle of nitrogen every day. Kelly's team had been unsuccessful in using the 'bubble test' for this application, and were contemplating the use of the helium.
This option, however, would not only require a lengthy period of time to set-up, but also to purge the transformer completely of the helium upon completion. Kelly's greatest concern was about the pressure in the system, since it was only 1 PSI. The transformer was de-energised for safety purproses, and Kelly began searching for the leak using their Ultraprobe 10,000.
After scanning the outer covers, bushing and man ways, Kelly was unsure if they would successfully locate this troublesome leak. The final area they checked was a cabinet containing isophase bushings, which was located on top of the transformer.
Eventually, the leak was found on the third bushing. This leak was so small that the Ultraprobe's display only read 2 dB on the maximum sensitivity setting. While the traditional helium method may have taken a couple of hours (or more), these checks only took a total of twenty minutes.
|
