CT saturation

[cranky108]

When does CT saturation become too much?

Yes CT saturation is a problem when it impedes a relays ability to determines when it needs to operate. But what exactly is that point?
I have heard numbers of 10 to 30% for electromechinical relays. but what is it for microprocessor relays?

 

[bacon4life]

Various relay vendors often have recommended calculations for each family of relays. Here is an example from SEL:

https://cms-cdn.selinc.com/assets/L...eePoint_AH_20200501_Web.pdf?v=20200504-195517

 

[salem]

some factors can cause CT saturation, like high connected burden, fault current value, and DC offset, fault angle inception, remanence/residual flux.
for numerical relays, normally relay manufacturers are giving CT requirements for their relays.