SCT-013-005 Potential Damage

Hi folks this is my first post.

Our house in Canada uses 8-9 KWh per day and 250 to 350 watts when no one is around. I want to use the 5A CT on each 120V leg for more resolution in the quiescent state in parallel with a 100A CT for the entire range. My question is at high currents say 80-100A cause damage to the 5A CT. Once it hits saturation I assume the secondary current maxes out and won’t melt the copper wire.

Also are all the windings the same so I can just change the internal resistor to better adjust the voltage range i.e. modify 100A into a 30A.


I’m a bit puzzled by those numbers: 250 - 350 W over 24 hours is 6 - 8.4 kWh, so you cannot be using much for the rest of the time. You can only use 100 A for 15 minutes to make up the difference!

Would it not be a better idea to monitor the high power load(s) separately?

I doubt that you will melt the secondary winding, however the waveform you get out will bear little relationship to the primary wave. If you are looking at the YHDC SCT-013- range, your best option would be to buy the 100 A : 50 mA and add the burden resistor of your choice, calculated to suit your needs.

A warning however: if you intent to regularly overload the input, you will certainly need to be very careful to protect the input circuit of your ADC. The 50 mA version comes with a TVS inside, that will go some way to limiting the output voltage, but it probably won’t be enough on its own. The test report in Resources > Building Blocks should give you some indication of how a CT will perform given that (mal)treatment, and from that you should get a good idea of what you’ll need to do.