CT typical resistance value

[Yuma]

Hi all,

Can anybody suggest typical values for the secondary resistance of these CTs?

50/1 A 15VA Cl. 1
50/1 A 10VA 5P20

These are fairly old CTs and I can't find the documentation from the manufacturer. Nor can I measure it because the plant cannot be stopped right now. My guess is something like 0,2 ohm, and in any case less than 1 ohm.

Thanks

 

[afroeeng]

If you know the number of turns and approximate dimensions of the cut and secondary tails you can calculate the figure using the standard resistivity value of copper.

 

[mgtrp]

Typical values for the resistance per turn of a CT are in the order of 0.0025 Ohms/turn. It is very unlikely that you are at 1 Ohm for your CT secondary resistance, and probably also below 0.2 Ohms.

 

[Yuma]

Afroeeng:
Thanks, unfortunately I don't have the data to make those calculations.

Mgtrp:
That is more or less what I was thinking. I'll assume 0,2 ohm and probably I'm still on the safe side. Many thanks.

 

[scottf]

Not to split hairs, but not all CTs are window-type CTs. For a HV or MV CT, you may not have any way of knowing the number of secondary turns.