Generic CT Clamp Setup ~12% inaccurate readings

Support
1

Hi, I’ve just installed Iotawatt and loving the granular data I’m able to get. I bought some generic SCT-013-050 50a/1v CT Clamps from here SCT-013 10a 20a 30a 50a 100a Open-Close-Stromwandler sct013 nicht-invasiver Wechselstrom sensor Split-Core-Stromwandler - AliExpress 502

I’ve removed the burden resistor from the CT clamps and that’s the only mod I’ve done. I’ve added them as inputs but not sure what to set the phase lead and turns values to. Someone in another forum with similar CT’s told me that Phase Lead of 3 and Turns of 1860 was correct and to leave the iotawatt Burden setting at 20, but I’m seeing measurements are inaccurate at about 12-15% too low. Ie, when I stand infront of my solar inverter screen to check live data it’s showing 3.632kw, but iotawatt Status is showing 3.109kw. It’s also not a fixed difference, could be 8% could be 15% depending on power levels measured.

My physical electricity meter doesn’t show me the actual live consumption/export, but I’m guessing the Grid feed value is correct because that is an unmodified 100a/50a CT, and you can see from the screenshot that I’m exporting more than the solar is reporting being generated (blue is my inverter). I’ll see if I can validate total day consumption from my utility company and compare to iotawatt.

Anyway, I was hoping that someone that has used these Aliexpress CT’s could advise on whether my configuration is correct, or what needs to change in order to get accurate results from the 3x50a CT’s.

Thanks in advance.

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2

What a bargain! $0.99 - 91% off. Makes you wonder how they can do it.

Two things:

The picture doesn’t say YHDC and there have been other inferior knockoffs lately.

Why didn’t you just get all 100A:50mA and eliminate the burden removal and guesswork? Still not sure it is genuine either but its picture does have the YHDC URL printed on it.

3

99c? My link says $5.81 AUD ripped off! Ha!

I’m not sure what YHDC is nor can I see a url printed on them.

Apologies I’m a bit new to this stuff. I was advised to get the 100a:50a for the grid feed and 50a/1v for the circuits so that’s what did. Was easy enough to remove burden resistors from them. I asked the seller if the knew the phase lead and turn ratio but of course they had no idea what I was talking about.

If there is a better option I’m happy to change, they only cost me $20 so can get different ones if that’s preferred.

4

Should I get the 100a/50ma or are there more appropriate CT’s? These 3 are monitoring solar, hot water and split system AC. For smaller circuits would 100a be too big? Thanks

5

If you can get one of the 50A:50mA CTs already in the table that would be best, but plenty of users have YHDC SCT000-100 (100A:50mA) and e we irks fine. Just hope you are not getting any of the counterfeits.