Today I was working with something unrelated and wanted to change the burden resistor on one of the input channels. Before I heated up the soldering iron, I picked up an old SCT013-030 and pondered. That CT has an intenal burden of 62 ohms which when combined with the IoTaWatt 24 ohm burden yields an effective 17.30 burden. That was close enough for what I wanted to do, so I just went to the setup tab, selected “Burden Resistors”, and changed one of the inputs from 24 to 17.3. I configured the input as generic with 1860 turns and phase 3. Plugged in the unmodified SCT013-030 and it reads exactly the same as a standard SCT013-000.
The 30 A version is starting to push the envelope but it gets better as you go down. Here’s a quick chart that I made up:
So what I’m saying is that if you configure one of these voltage type CTs as generic 1860 turns phase 3 (wag), and set the burden for that input to the “Combined Burden” value in the table, you should get decent results.
This approach eliminates the need to do anything with burden resistors. I’ve not tried it with models other than 30, but it’s worth a look.
Newer IoTaWatt now in manufacture will have 20 ohm burden, so the table changes a little:
