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Sepam delay set while in TMS mode changes after being applied

Any delay set in the Sepam while in TMS mode will become adjusted after it is applied

Product Line
Sepam Series 20, 40, 80


Sepam and SFT2841 software tool can work with the two setting modes: 10 I/Is or TMS. Natively, Sepam is working with 10 I/Is mode which gives the tripping time in s (or ms) for a current 10 times higher than Is. This tripping time has a resolution of 10 ms. This means that if you enter a tripping time of 258 ms, SFT2841 will display an Out of range box reminding you the minimum and maximum values but also the step which is 10 ms. So in this case, you will have to chose the closest value acceptable by SFT2841, which would be here 260 ms.

Now if you are working with TMS mode, and you enter a delay of 2, SFT2841 will adjust this value to transform it to a value acceptable in 10 I/Is mode by Sepam (meaning with 10 ms resolution for its delay). A delay of 2 in TMS mode is equivalent to a delay of around 185 ms that is not acceptable by Sepam (due to resolution issue of 10 ms). To double-check this you can use SFT2841 to modify the settings in two different modes available. 

In 10 I/Is Mode: IAC Ext Inv, Is = 480 A, Ts = 180 ms settings is equivalent to TMS Mode: IAC Ext Inv, Is = 480 A, Delay = 1.944. In 10 I/Is Mode: IAC Ext Inv, Is = 480 A, Ts = 190 ms settings is equivalent to TMS Mode: IAC Ext Inv, Is = 480 A, Delay = 2.052.
According to our documentation, TMS settings resolution is one digit, which is what we find here.

The setting mode can be different on SFT2841 and on Sepam and this can be independently set on each. Engineer can prefer working with TMS mode on SFT2841 while technician who are doing commissioning tests can prefer working with 10 I/Is mode that give them directly a tripping time for 10 Is. On SFT2841 side, the setting mode is set thanks to Options/Setting Mode… menu. On Sepam side, the setting mode is set within General settings menu.
Thus, the conversion is being done to force the delay to be compatible.
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