Current transformer connection

[neluvel1210]

We have three current transformers to protect an asynchronous motor. We connected the ends of the three phases of the engine to the terminals P2 and realized the star to the terminals P1. Does it matter that we didn't connect to P1? Of course it will take into account the meaning of the secondary wraps of the Transformers.

 

[RRaghunath]

Your connection is more appropriate for Voltage transformers, unless you mean motor star point (CT primary doesn't have star point) and the CT type is wound CT. Bar primary CTs are more common.
If the above understanding of mine is correct, the answer to your question is - it doesn't matter how you connect P1 & P2 in the CT primary circuit. However, general convention is for CT secondary star point and that is 'Towards Object'.

 

[JG2828]

For everyone who doesn't like to download files:

 

[neluvel1210]

Thank you for your answer. The U2, V2, W2 are the ends of windings terminals of stator (not shown on image attached). In series with every phase is introduced a current transformer with P1 and P2 terminals. The star for stator winding is realized on current transformers.

 

[waross]

If the P1 terminals are the motor star point, then it doesn't matter. Motor star points are never connected except when CTs are inserted for motor protection or differential protection.
Then the star point is made up (P1 to P1 to P1) and insulated.




Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[neluvel1210]

Thank you. The current transformers are used for motor protection.