I've been reading up alot on how to work with a CT. Basicly you have a primary current (eg: 100A) and a turns ratio (eg:1:2500) and a load resistance (eg:5 ohms) so now things are straight forward we can calculate the secondary current (40mA) and let's put a burden resistor 3 ohms to get 120mV while not exceeding the maximum power the CT can deliver. Now I'm currently working on an energy meter design, and while looking for the suppliers i'm getting these specs. enter image description here As you can tell the supplier is giving out " Rated primary current " and " Max primary current". I've opened a 80A rated energy meter and found out the CT's have a writing " 5 (80)A / 2.5mA/0.1 " , is it 5A or 80A ?

My questions :

  1. On an absolute maximum load 100A will this CT not saturate ?
  2. How can i work with this thing ? is it supposed to be saturated somehow and still work on both spectrums ?


Finally got a response from a supplier. The response is as follows,

enter image description here

  • 1
    \$\begingroup\$ Can you provide a link to a proper data sheet? \$\endgroup\$ – Andy aka Sep 19 at 15:07
  • \$\begingroup\$ I would interprete the rated primary current as the current for which the given accuracy is valid and the transformer would not overheat when operated at this current for a very long time. The maximum primary current is valid for a short time and with less accuracy. Details should be given in the datasheet. If not, I would look for a part with a better datasheet. \$\endgroup\$ – Uwe Sep 19 at 18:17
  • \$\begingroup\$ I can't find a good datasheet from any of those "CT for metering application" manufacturers. I've sent several emails asking for more information. If i get any more information i'll update the post for anybody who may fall in my situation and hopefully finds it useful \$\endgroup\$ – Sultanpepper Sep 21 at 19:42

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