Westinghouse UTT On Load Tap Changer Failures

[dithomas]

Has there been documentation or studies done on the failure rate of the old Westinghoue 13.8kV UTT on load tap changers?
These are the units with arching type transfer switches.

I have two if these units in service built in 1967 and on 12MVA 69/13.8 transformes. Both with close to 400,000 operations. I would like to present the case to the owner to be thinking about replacing the units and would like to present some failure data.

Dan

 

[prc]

Probably you may get the data from Doble Company. But do you want such data to replace a 50 year old accessory with moving components? But since the transformer has also completed that many years of service,the best policy may be to leave the whole equipment as such with some non-invasive maintenance and cost effective diagnostics.

 

[jschwei314]

As a customer: Do I need a Load Tap Changer? What happens to my site if I do not have a LTC?

 

[dithomas]

jscwei314,

That is a rather good riddle!!!!
The 69 kV line is an unregulated line and my swing 10 to 15 pecent.
If and LTC is on a transformer and left on one tap coking can form on the contacts.
Will vfd and 2300 volt motor tolerate a + - 15% swing?
What is the weather like?

D

 

[stevenal]

While I prefer a lower maintenance vacuum style LTC, I cannot recall any failures of UTCs. Gas-in-oil testing will tell you much.