Current Transformers
I see a great deal of different ideas of how to hook up current transformers for inverter limiting. So, the theory first.
This link covers it very well. The relevant line is: V= [I (pri)/N] x R. This is Ohm's Law. The transformer is providing current across the burden resistor, not voltage. When working with a current source the appropriate math and circuit must be applied. It is because there is a burden resistor driven by current that we can get a voltage reading. If there were no resistor the voltage across the CT would go theoretically infinite. In the link there is talk about how these are protected from an open circuit with zener diodes. If you were to pull the coil up on a SCT013-X3, the CT that ships with these inverters, you will find a zener.
So the voltage signal is a result of the value of the burden resistor. These inverters use a 50 ohm resistor in the inverter.
The first misconception, that the wires from the CT to the inverter can't be longer than X. In my application I've got 60 feet of #18 zip cord running from the CTs at the mains to the inverter. Yet the reading is spot on. The reason is the CTs are current sources. They will put out what ever voltage is necessary to deliver the current, I (pri)/N to the burden resistor. Resistance is series will have no effect on the voltage at the burden resistor. And because it is about current, noise is not really an issue.
Second misconception, If you are using more than one CT, they have to be put in series. It doesn't make any sense to put current sources in series, they should be put in parallel. You put voltage sources in series. And unless the voltage sources are the same V, it won't work to put them in parallel. With two CTs, the current is doubled. So we need to bring the burden resistor down to 25 ohms to get the same voltage reading. In my case:
View attachment 25742
I used a 47 ohm resistor. This keeps the real load at 30 watts on the service while the inverter sees 0 watts. The difference in the two readings remains 30 watts when I'm not limiting. It works solidly, when I hovered over the two hours in the graph above, they both said 30watt-hours.