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Is the cycloaliphatic resin insulator a good insulator? problem about flashover, corona cutting, tracking, vandalism. Please friend help me!
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Epoxy resin cast insulator ha considerable satisfactory experience for more than 30 years in the electric power industry applied by worldwide recognized manufacturers such as ABB, Alstom, Square-D, Cutler-Hammer, S&C, Powell, etc.used by many utilities and industrial facilities.
Cycloaliphatic Compound Insulators had been extensively used in indoor MV switchgear and later for outdoor electrical apparatus such as oil transformer bushing, spacer insulator, air insulated substation and SF6 Insulated switchgear.
Recent test in several epoxy compound formulation confirm the adequate tracking and erosion resistance for outdoor use. In addition, the insulators evaluated did not flashover at nominal service voltage (and higher) under a wide range of simulated contamination conditions.
The overall good performance of the insulators has been related to material formulation, design, and manufacturing of the insulators.
There is available in the market a new generation of cycloaliphatic epoxy insulation material with enhanced hydrophobic properties.
There are several suggested references that could be consulted as follow:
1. Experiences with New Hydrophobic Cycloaliphatic Epoxy Outdoor Insulation Systems, C. Beisele and B. Kultzow.
2. Electrical Performance of Cycloaliphatic Epoxy Materials and Insulators for Outdoor Use, Gorur, R.S.; Montesinos, J.
3.
4.
Cycloaliphatic Compound Insulators had been extensively used in indoor MV switchgear and later for outdoor electrical apparatus such as oil transformer bushing, spacer insulator, air insulated substation and SF6 Insulated switchgear.
Recent test in several epoxy compound formulation confirm the adequate tracking and erosion resistance for outdoor use. In addition, the insulators evaluated did not flashover at nominal service voltage (and higher) under a wide range of simulated contamination conditions.
The overall good performance of the insulators has been related to material formulation, design, and manufacturing of the insulators.
There is available in the market a new generation of cycloaliphatic epoxy insulation material with enhanced hydrophobic properties.
There are several suggested references that could be consulted as follow:
1. Experiences with New Hydrophobic Cycloaliphatic Epoxy Outdoor Insulation Systems, C. Beisele and B. Kultzow.
2. Electrical Performance of Cycloaliphatic Epoxy Materials and Insulators for Outdoor Use, Gorur, R.S.; Montesinos, J.
3.
4.
BenNeideck
Electrical
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?
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 can share some experiences on stability of dimensions and curing methods. The manufacturers of the resin recommend certain gelation cycle followed by further curing cycle. You can follow the cycle suggested by the manufacturer or you may have to devise your own process to achieve best results. This is particularly done as post curing treatment.
Our experience ( for glass filament reinforced)reveal that the cycle recommended is just not sufficient.
In general parlour you can call it heat treatment that is to be done at elevated temperature such that the curing process is almost completed. With this you will get dimensional stability and can avois biuld up of stresses due to shrinkage at a later date.
in our application, we had gelation at 80 deg for 2 hours followed by 3 hours at 140 deg C followed by 3 hours at 160 deg. The last cycle may be increased to get better stability. This was for a system comprising resin CY184 and Hardener HT907 of Ciba Specialty.
With this you will increase glass transition temperature and can get better thermal properties.
Good luck
Our experience ( for glass filament reinforced)reveal that the cycle recommended is just not sufficient.
In general parlour you can call it heat treatment that is to be done at elevated temperature such that the curing process is almost completed. With this you will get dimensional stability and can avois biuld up of stresses due to shrinkage at a later date.
in our application, we had gelation at 80 deg for 2 hours followed by 3 hours at 140 deg C followed by 3 hours at 160 deg. The last cycle may be increased to get better stability. This was for a system comprising resin CY184 and Hardener HT907 of Ciba Specialty.
With this you will increase glass transition temperature and can get better thermal properties.
Good luck
If you are going to do it yourself, be careful about eliminating ALL air bubbles. Epoxy is such a good insulator that you will get quite a bit of PD in the bubbles. Even the big bys have difficulty with this, and we have some 33kV metalclad boards with epoxy encapsulated busbars, CTs etc which are a real nightmare for PDs. Even a layer of dust seetling overnight can dramatically alter your PD readings!
Epoxies seem to be reasonably good at voltages below 33kV, but the jury still seems to be out at 33kV and up, for outdoor use. Or is somebody willing to show that am I wrong? (A user, that is, not a salesman!)
Bung
Epoxies seem to be reasonably good at voltages below 33kV, but the jury still seems to be out at 33kV and up, for outdoor use. Or is somebody willing to show that am I wrong? (A user, that is, not a salesman!)
Bung
Sportbikenut
Electrical
I've done quite a bit of work with cycloaliphatic. The resin is quite amazing, however the trick is:
> Filler content / loading
> Manufacturing process and resin mix process
> stress relief
> bushing design
I've designed bushings that have performed quite well, with over 20 years in the field. But I've seen copies of my parts that eroded badly, simply because of a few differences in the filler and process. I've found that the epoxy vendors have a pretty good idea of what their products will do, but nothing beats field experience.
In most cases, I find that failed parts are a result of poor product design, not material considerations. Material problems tend to take much longer to show up (unless they are way off on the mix), while design problems show up in about 3-6 years. How the product handles water on its surface is very important. The part should be tested at electrical levels far beyond what most engineers (and standards) assume. The surface material will degrade somewhat and the design must take that into account. Once you get PD, the part erodes rapidly. I've seen designs that performed better covered in salt water, than clean new parts. It's pretty easy to create parts that pass test when new, but it's much harder to create parts that will still pass after 10 years.
> Filler content / loading
> Manufacturing process and resin mix process
> stress relief
> bushing design
I've designed bushings that have performed quite well, with over 20 years in the field. But I've seen copies of my parts that eroded badly, simply because of a few differences in the filler and process. I've found that the epoxy vendors have a pretty good idea of what their products will do, but nothing beats field experience.
In most cases, I find that failed parts are a result of poor product design, not material considerations. Material problems tend to take much longer to show up (unless they are way off on the mix), while design problems show up in about 3-6 years. How the product handles water on its surface is very important. The part should be tested at electrical levels far beyond what most engineers (and standards) assume. The surface material will degrade somewhat and the design must take that into account. Once you get PD, the part erodes rapidly. I've seen designs that performed better covered in salt water, than clean new parts. It's pretty easy to create parts that pass test when new, but it's much harder to create parts that will still pass after 10 years.
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