Recent content by a430

Hello everybody, Iam with electricpete,check for any loose connection on the CT circuit.

Hello everyone, I have been invited to present a paper in a seminar on engineering safety can someone help with some inputs please.

Hello Ralph, It is really very stange,the earth fault is always on the primary and is the secondary relay that always flags, the Ncts are not on the point,but they are connected to the same station ground,and are very close to each other.

Hello Hi-set please how did you solve the problem ? or are you still having the trippings?

Thanks alot scotty, Like you rightly said, the scheme is the Hi-z type,and after carrying out a magnetisation test, i discovered that the X-class cts on the nuetral bushings have higher knee points than the out-door cts on both primary and secondary, that was why i replaced it with standard type...

HI,everybody. I have a 90MVA 330/132/13.8KV Yyd transformer that always trips on REF due to an earth fault on the 330KV line,and is very stable during normal loading. I have sometime ago carried magnetisation test on all CTS and discovered that the ones on the Neutral bushings were of the X-...

Hello Everyone, I have a project to install an 18.5MVA Transformer, the client beleives he has an excellent and reliable Differential protection and thus doesnt need an REF protection,how do we convince him.

Hi khadisa. I have not heard of such class of Cts,and on the Seimens can you please send more details, is it a single core? or wnat is it like.

Hi everyone. Iam sorry, i mean MCSU Alstom type.

Hi everyone. please, if i must protect my transformer for REF,then can anyone recommend Alstom VCSU earth fault relay for this purpose. Thanks.

Hi everyone, I will please like to know if i can use nuetral earth fault protection in place REF in a star Delta transformer.Wnat is the implication of not providing REF protection on Y/D transformer.

Hello Khadisa/Unclebob. If i understand what you are trying to say, your transformer is star/star and therefore your CTs should be in delta both sides.

Hello davidbeach. What i understand is that there is a terminal to be connected to a star point, that is terminal 27, and even if he eliminated the interpossing CTS that terminal will be left unconnected since inputs to the relay will both be in delta.

Thanks Ralphchritie I have earlier on carreid magnetisation test on the cts,and discovered that the bushing one is not the same class with that of the outdoor, and thus shorted it out and mounted one with similar charecteristics,and the relay type is CAG14ZF14A. The circuit was designed a very...

Thanks Ralphchristie. It is a high impedance scheme,and at one time i treid to reverse the polarity during some checks on stability and discovered it to be more stable the way it is at the moment.