The very useful advantage of open delta connection is to
detect ground fault at any bus or line of a system. usually
open delta connection transformer is used in potential
transformer to detect ground fault as a 3rd core of PT.
By the open delta connection of PT we can monitor the
neutral shifting of the system as well as it can be use in
the genetating end substation for the maintenance of the
transformer in the time of low load demand.
When we change the tap position of 10MVA transformer it
suddenly tripped with Out of step indication and also with
Static differential relay indication, Transformer Bucholz
relay indn and Low oil level indication. Before 1 week the
same problem occured by changing the tap position. but at
that time only oltc bucholz relay activated. After testing
the TxR Relay team & PET team cant find any solid reason.
The values are ok also. So plz answer wat's the reason for
this incident? anybody plz help.