Checkbox to turn on 87T protection is disabled in SFT2841 for Sepam Series 80

搜尋常見問題

Issue
User is unable to enable 87T protection because the checkbox is disabled or grayed out and cannot be checked.

grayed out on box

Product Line
Sepam series 80

Environment
SFT2841 Software

Cause
The relay does not meet the Un1/In and/or Un2/In' constraints:

CT formula

Notation:

S: HV/LV transformer rated power
Un1: Winding 1 rated voltage

Located in SFT2841 Sepam settings > Particular characteristics: "Un1"

Un2: Winding 2 rated voltage

Located in SFT2841 Sepam settings > Particular characteristics: "Un2"

In: Winding 1 CT rated current

Located in SFT2841 Sepam settings > CT-VT sensors: "Rated current (In)"

I'n: Winding 2 CT rated current

Located in SFT2841 Sepam settings > CT-VT sensors: "Rated current (I'n)"

Resolution
Verify the Sepam configuration.

Sepam settings > CT-VT sensors: confirm that values are correct for the CT rated current on both Winding 1 (In) and Winding 2 (I'n)
Sepam settings > Particular characteristics: confirm that values are correct for the rated voltage on both Winding 1 (Un1) and Winding 2 (Un2) sides. Also verify that Rated Apparent Power is correct.
Once the system configuration has been validated, verify that the equations listed under "Cause" are satisfied. If the equations are not satisfied and all system configuration is correct, 87T protection may not be supported on the specific system.