PT Ratio Meaning

[NorEE]

Kind sirs,

Please englighten me with this issue.

We are using PT with Ratio: 13.8 kV/3R/110V/3R/110V/3V

What does this mean?

Thank you in advance and sorry for the ignorance.

 

[DTR2011]

I would guess that the 3R is 1/Sqrt of 3

see

http://eng-tips.com/viewthread.cfm?qid=321282

for more on PTs with similar markings.

 

[NorEE]

i guessed as much. but im baffled w the 110/3V thing..

 

[DTR2011]

I believe the consensus was that the divide by 3 winding was to be feeding a 59N relay, used as a ground (earth) over voltage relay.

Do you have schematics to confirm that this is what is connected to the PT?

 

[scottf]

Correct...110/3V winding would be connected in a broken delta configuration and used for zero-sequence voltage detection.

 

[NorEE]

smallgreek,

thank you for the insight sir. i will try to upload the diagram for the connections.


scottf,

sir i believe both you and smallgreek are correct on this. thank you for your time.

 

[DTR2011]

@scottf-

As far as nameplate data requirements are concerned, is there something new in relevant standards that calls for this? I don't recall seeing that in North American standards.

@NorEE-

You are welcome! Please post a picture of nameplate, if you can.

 

[scottf]

smallgeek-

No, this is normally seen in IEC applications.

IEEE VTs would normally use a 120V rated secondary or 69/67V rated secondary.

 

[NorEE]

@smallgeek,

sir sorry for the late reply.

For now i can only provide a connection diagram as the plant is currently running and their are no provisions to take pictures of VT nameplates. ^^