capacitor bank for transformer test

[Pafi]

Hello!
I would like to ask if someone knows anything about how the large - 100Mvar/ 6kV - capacitor bank used for high power transformer load test can be protected. It is a special case where this bank is used only for 5-6 hours at a time and only few times a year. Maybe someone is working in transformer producing companies where this method is used and knows more about this subject. I was thinking to divide it in several parts and use double star connection for each with unbalance relay.
Any comment is highly appreciated!
Thanks!
Pafi

 

[electricuwe]

Using a capacitor bank for transformer testing seems quite strange for me. However, for protection you can monitor:

- the difference in voltage between the midpoints of several branches (using series connection) in parallel

- the difference in current between different parallel branches

- as considered by yourself: the difference in starpoint voltage in a double star connection

In all cases the initial difference would be small and only a function of tolerances whereas a fault would cause a large difference.

 

[ghostbuster7]

Cap banks are sometimes used for the 180 hz. induced test, especially if it is a reactor.Usually the 180 hz. M-G sets are not large enough to handle this type of load.Cap banks are used to offset this high inductive loading factor.