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iwire:
Your method will work assuming everything is phased correctly. If not phased correctly you have enough experience to know of the problem and how to correct it.
On accuracy. If the CT is a split core type, then centering is probably a greater problem. Following are two experiments.
1. Fluke 8100Y Hall type split core probe with a 3/4" diameter hole. Current wire was #12. Load my 1500 W heater. Max-min readings with the wire in different positions was 11.02 to 11.15. This probe is out of calibration, but that does not affect this experiment. The error here from position differences is about 1.2%. The maximum error is not from center to one side but from one side to another. In other words this split core has substantial leakage flux.
2. A home made current transformer. This is using a continuous tape wound core with no split air gap. Very high permeability material, probably Supermalloy, bought probably 40 or more years ago from Arnold. Since my purchase of the core Arnold sold their tape wound core business to Magnetic Materials.
This transformer is very crudely made. I wound 10 turns loosely on only about 1/8 to 1/4 of the toroid circumference. The center hole of the core is about 1.2". The total variation in current measured for any position of the one #12 wire thru the toroid hole was 10.56 to 10.55 or about 0.1%. And this might be more a result of line voltage variation than wire position in the core.
http://www.magmet.com/tapewound/
http://www.magmet.com/tapewound/intro2.php
I suggest you experiment with one of your CT units and evaluate the variation in current output for position variations.
A question. When you normally apply a fixed CT are there components supplied with the CT to hold the wire in the center, or is there normally no problem with wire position? I suspect that good commercial CTs for fixed applications use continuous tape wound cores and thus wire position is not a major factor except for very high precision.
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