CT saturation detection algorithms
CT saturation detection algorithms
(OP)
Hi
On reviewing the CT specs for a trfr diff scheme, I noticed that the CT kneepoint voltage (specified by the manufacturer) is way below my calculations. The CT and protection scheme is provided as a package by the manufacturer. I came up with a value for the transient dimensioning factor, Ktd, of 25. The manufacturer uses a value of 4. They claim that it is not necessary for a higher Ktd and subsequent Vk, as their relays' CT saturation detection algorithms will ensure stability.
The CT they design only provides 0.14V/turn. I would have preferred at least 0.5V/turn.
Local utilities around here tend to ignore the relay saturation detection algorithms when specifying CT's and base it on first principles. Result is much larger CT's but that's what the utilities insist on.
I would like to hear experiences of others as to in-field experience of the saturation detection algorithms and whether these are factored into CT sizing calcs.
Thanks.
On reviewing the CT specs for a trfr diff scheme, I noticed that the CT kneepoint voltage (specified by the manufacturer) is way below my calculations. The CT and protection scheme is provided as a package by the manufacturer. I came up with a value for the transient dimensioning factor, Ktd, of 25. The manufacturer uses a value of 4. They claim that it is not necessary for a higher Ktd and subsequent Vk, as their relays' CT saturation detection algorithms will ensure stability.
The CT they design only provides 0.14V/turn. I would have preferred at least 0.5V/turn.
Local utilities around here tend to ignore the relay saturation detection algorithms when specifying CT's and base it on first principles. Result is much larger CT's but that's what the utilities insist on.
I would like to hear experiences of others as to in-field experience of the saturation detection algorithms and whether these are factored into CT sizing calcs.
Thanks.





