CT Saturation Test: : Should H1 and H2 be open? 2

[kwaedza]

Would like to be sure about doing a CT Saturation Test. I am a ware that the best would be to apply a variable voltage at the secondary X1 and X2. But tel me, must H1 and H2 be left open or must shorted (this looks unlikely for testing large CTs inserted in transformer bushings or swtchgear, though).

 

[rcw retired EE]

Open circuit H1 & H2 for saturation test. A high accuracy, high impedance voltmeter across H1 - H2 during the test will give data for the turns ratio test.

Example: 1200:5 C200 ANSI CT. With 120 V across X1-X2, 0.5 volts will appear on H1-H2.

 

[scottf]

Yes, primary must be open-circuit for excitation/saturation test.

Keep in mind on bushing CTs, you're likely not testing them while the device (transformers, breaker, etc...is energized. As long as there is an isolation switch open on the high side, then that is an open-circuited primary.

 

[Millbo]

Your more than likely using some sort of CT test set. The auto and semi-automatic ones will take care of opening the H1 to H2 circuit for you during your saturation test and will close that circuit to measure the turns ration as well as verify polarity.

In short:
Like the others said yes, they will be open.