Miniaturisation of CT Sensors

Hi everyone,

I am new to the world of electronics and in my final year of an Open University course I am working on a project which would look to take the existing electricity monitoring technology and develop it to measure every outlet in a property rather than the property as a whole.  However, fundamental to my project is the ability to miniaturise products such as the split core current transformer (SCT013) discussed elsewhere on this site.

The question that I really need some help with is whether in theory this would be possible and what are the challenges that the theory faces?  My thought process is that the aforementioned product is designed to fit around a particular size of cable, but if the cable is smaller e.g. a live wire to a plug socket, is it simply a case of scaling down the technology to get the same result?

Any insight would be very helpful.

Thank you all in advance.

Robert Wall's picture

Re: Miniaturisation of CT Sensors

You need to consider things like frequency response, inductance, and core saturation - in general you need to learn about transformers! The requirement to pass a 50 Hz signal without attenuation inevitably means that there is a minimum value of inductance that will "work". It's possible to make smaller CTs than the YHDC SCT-013-000, especially if you do not need a split core, but it's a mistake to think that a single wire of around 1.5 mm2 CSA is the norm. For many people, especially in the USA, even the YHDC one is too small.

inquisitive student's picture

Re: Miniaturisation of CT Sensors

Dear Robert,

Thank you very much for your feedback. I will certainly investigate transformers and increase my understanding of the challenges. You give me confidence that in theory at least, my thinking is not ridiculous. 

Kind regards. 


Eric_AMANN's picture

Re: Miniaturisation of CT Sensors


I can't help you in your investigations but I think it is very interesting idea.

In some electrical fuse box (see attached), the CT used in this project (SCT013) is just too big.

A smaller CT would be great ! Or at least a CT that can be split in two parts like this one (the black CT on the left)



inquisitive student's picture

Re: Miniaturisation of CT Sensors

Dear Eric,

Thanks for the feedback.  Your image did help me as I had not considered the fuse box itself and fitting sensors that way, which is obviously the easiest solution, but as you have demonstrated, messy.  I am thinking that sensors built in to the plug socket itself, using the buildings electrical system to send the data back to a transmitter, would be ideal for new buildings.

Following Roberts advice above, I have a very basic understanding now of transformers, but am struggling with the scale issue as everything is just numbers and scientific language to me.  I am thinking that better minds than mine will have worked this out, however, if it is not possible to reduce the size of the sensor, in a new build, I don't think that it would be difficult to design the casings that fit them.

Thanks for your help.



Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.