Retrofitting Reyrolle LMT breakers with cycloaliphatic resin bushings

[BenNeideck]

I am currently researching the possibilities of manufacturing bushings to replace paper wound condenser type bushings that we have on Reyrolle LMT X1 type 11kV circuit breakers in our distribution substations. We have a number of these breakers that are experiencing PD problems on the bushings, and rather than replace the whole breaker we are hoping a cheaper more viable option may be to make Cycloaliphatic Resin bushings.

The original bushings however have a form of stress relief. What I am trying to find out is whether or not we would need to include some sort of stress relief in the Cycloaliphatic Resin bushings as well.

Can anyone help with any technical data or ideas on this type of resin, both in general and also more specifically in regards to the stress relief?

Also, is anyone aware of companies that have had similar problems with LMT breakers (or similar) and what their solutions were?

 

I am currently employed within the Reyrolle organisation, and until recently was the Chief Engineer for the Distribution Switchgear Business.
With regard to your bushing situation, you need to apply a great deal of care if you are considering changing the design of the product. You cannot deal with the circuit breaker in isolation, the field control around the primary bushings is influenced by the proximity of the earthed metalwork when the breaker is in service. We have a great deal of experience with this in our retrofit business with both screened and inscreened bushings. We have found that the best solution is to.
(a). Identify that the discharge is real and of a level to cause concern,
(b). Ensure that your substation environment is within reasonable parameters to prevent future problems. (There have been more than 100,000 panels of LMT switchgear sold around the world during the past 40 years, and bushing discharge problems have not been experienced if the substation environment is reasonable.)
(c). Retrofit the Oil Circuit Breaker with our Vacuum replacement. This breaker retrofit is extremely cost effective and it has been fully tested in conjunction with LMT fixed portions to IEC standards. It also gives the added benefit of reducing maintenance, improving SCADA and increasing the fault rating of the entire switchboard usually without a busbar outage.

I hope that the above is useful to you. Once again I would advise against carrying out design modifications to the original equipment that could compromise its short circuit performance.
We can provide spares, retrofit, refurbishment, repair and technical support for LMT and other aged Reyrolle products.

Regards,
Richard Blakeley,
VATech Reyrolle.