Surge suppressors

How to make an application design for the requirement of surge suppressors for SF6 / VCB breakers feeding transformers and motors. In this case the surges deveoped by the breaker due to chopping currents / virtual chopping etc and not related to external circuits .

 

[electricuwe]

I'm also aware of the fact that this may cause a problem especially for cast resin transformers but I do not know a good reference for specifying a surge suppressor for that application either.

Does a SF6-breaker behave the same way as vacuum breaker ?

 

[cuky2000]

Even thought the modern design of vacuum breakers use special alloy that made the chopped wave more friendly, still surge caused by vacuum breaker may be a concern for dry insulated machinery such as motor or dry type transformer do to their lower dielectric withstand capability.

A surge mitigation strategy could be using arrester and surge capacitor. However the initial cost, O&M and space required by those surge mitigation devices should be evaluated not only from the technical but from the economical stand point.

For oil insulated apparatus the BIL rating is higher and the surge created by vacuum breaker is not a concern.

SF6 breaker performs better than the vacuum from the surge point of view.