Secondary Y-ph Earthing of Potential Transformer

Something sounds inconsistent about this. There are such things as "corner grounded" configurations, but I'm unsure why there would be a fuse in the grounded phase.

In addition to #1,

The Why: because, if the star point is grounded, with the Y-phase also grounded, you will get a short circuit through the ground !

Er, because the drawing is wrong?

Mr. Giri, try the Instrument Transformers - A Reference Manual by Kappa Electric.

For clarity,the picture is posted here with the grounded part part is clouded.

Mistakenly I have written that ground is given after the fuse.Its actually before the secondary side MCB.

Pls help!!!

Does this drawing depict accurately the actual installation at site?

Has the question been asked of the individuals and organisation that produced it?

Dear PWSlack...I didn't get the answer from any corner,neither able to ask the manufacturer.So thought of getting help here.:)

Does this drawing depict accurately the actual installation at site? Please check, then answer either yes or no, as either response will enable the forum to help with the query appropriately.

The actual wiring can only be checked during the panel shutdown,by drawing out the PT module.This kind of wiring is shown in HT & LT panels.If anybody aware of this pls help...

Dear,

Giri,

Usually, Y-phase of the secondary side is grounded(intentional ground) and copper link(not fuse) is used.In case of any earth fault in the secondary circuit of the of the PT, the short circuit current flows thro' the circuit , completed the current loop thro' the two ground points(one in Y-phase and other grounded point) and blowing up the fuse to protect the PT.

Thanks,

Manindra.

Dear Manindra,

What I am not able to understand is that ,if we ground any phase directly,the protection equipment will trip/must trip,in this case its primary side fuse.(HT fuse).why this is not happening.

The above answer by you doesnt solve my question fully.

(No,its not grounded after fuse.I wrongly told this.Primary side fuse provided.Secondary side MCB provided & the grounding is provided at secondary before MCB)

Thanks for your interest though:)

Unfortunately I don't have the answer to your query, but am writing this to confirm your observation. In some of our installations which are more than 40 years old, 110V PT secondary is connected like this. Y-ph is solidly earthed and neutral kept floating. I am also confused about this. This seems to be the old practice as I see the same configuration repeating in panels supplied by Brown Boveri and Reyrolle.

Newer panels come with neutral grounded pt secondary.

In old installation, in various panels, instead of neutral point earthing of secondary of P.T., Y-Phase( middlle phase) is earthed (intentional earth ), so that, in case of any earth fault in secondary circuit, fuse provided in the secondary circuit(in other two phases of P.T.) is blown off to protect the circuit and various instruments connected in the secondary circuit.

Manindra.