Interposing PT open delta to star/star connection.

[keyrose]

Hi everyone,

I did mistake in choosing interposing PT. Now I want to use it by changing PT connection.

I have 12kV/120V main PT open delta to open deta connection and interposing PT is 120V/120V delta/star connection. Secondary of interposing PT is connected to distance relay. I need 120V phase to phase in relay terminal and with this connection I am getting 208V phase to phase. (I would have to select 120/69V interposing PT.)

Now I want to change interposing PT from delta/star to star/star to get 120V in relay terminal.

Can I do this? As secondary of main PT is open delta and centre line is connected to earth.
I want to remove ground from centre line of open delta and want to change interposing PT to star/star

I have attached the drawing. Please comment.

Keyrose

 

[davidbeach]

What's the point? You still have that open delta in the circuit, you still have thrown away all the zero sequence voltage information. Do yourself and your relay a huge favor and fix the main VT. Also, any decent relay can take 69 or 120V line to neutral.