CT Polarity Tests

Does AC have polarity?

Every 50 or 60 times a second.

Are you saying that you are an engineer? How is it then that you cannot posit a legible question on a basic engineering forum?

Rectify me if my understanding is in the negative half of the cycle.... but here is what polarity of a CT means (for those who dont understand it) with respect to EMI circuits: When AC is given to the Primary coil (P1-P2) with P1 +ve and P2 -ve during first half cycle which induces +ve on S1 and -ve on S2 of the Secondary coil then the polarity of the coils are said to be same else opposite. I hope I am clear!!! :)

The primary side of the current transformer (CT) is the one with the big hole.

http://en.wikipedia.org/wiki/Current_transformer

OK so not everyone has come across a current transformer before, but still a simple search (by you) of the internet would have produced the answer immediately.

One more little point, please spell 'enginer' as 'Engineer', misspelling is one thing (it happens to all of us) but misspelling or misusing the title 'Engineer' is one of my 'hot buttons'.

http://www.thefreedictionary.com/hot+button

Jack - Electrical Engineer

CT must have polarity and it is important to identify the polarity correctly. The incorrect polarity will affect the Watt meter, Energy meter, pf meter, Differential protection, Reverse power protection, Directional over current protection, comparator etc. (if the CT is used for these purpose).

I posted the simple CT polarity test method before (see http://cr4.globalspec.com/thread/33197). It is again pasted. I tested CT polarity by using this method - it is very simple and very easy.

"All you need a 1.5V dry cell battery, a analog multimeter and few pieces of wire. Connect the multimeter in CT secondary to measure DC current. Quickly connect and disconnect the battery in the primary. You can now find the primary terminal entering the current (connected to the positive terminal of the battery) and secondary terminal exiting the current (from DC ammeter polarity). It is so simple, quick and interesting."

If it is a ring like CT, pass a wire through the ring and consider one end of the wire S1 and the other end S2.

- MS