sepam 20 user manual - Schneider Electric
sepam 20 user manual - Schneider Electric
sepam 20 user manual - Schneider Electric
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Protection functions Overfrequency<br />
ANSI code 81H<br />
PCRED301005EN - 06/<strong>20</strong>08<br />
Operation<br />
The protection function picks up when the positive sequence voltage frequency is<br />
above the set point and the positive sequence voltage is more than <strong>20</strong> % of Vnp<br />
(Unp/3).<br />
If a single VT is connected (U21), the function picks up when the frequency is higher<br />
than the set point and the U21 voltage is more than <strong>20</strong> % of Unp.<br />
It includes a definite time delay T.<br />
U32<br />
U21<br />
Vd<br />
MT10542 Block diagram<br />
Vd > 0.2 Vnp (1)<br />
(1) or U21 > 0.2 Unp if only one VT.<br />
If there is only one sensor (U21), the voltage signal is connected to terminals 1<br />
and 2 of the connector CCT640, whatever the phase.<br />
Characteristics<br />
&<br />
F > Fs<br />
Fs set point<br />
Setting 50 to 53 Hz or 60 to 63 Hz<br />
Resolution 0.1 Hz<br />
Accuracy (1) ±0.1 Hz<br />
Pick-up / drop-out difference<br />
Time delay T<br />
0.2 Hz ±0.1 Hz<br />
Setting 100 ms to 300 s<br />
Accuracy (1) ±2 % or ±25 ms<br />
Resolution<br />
Characteristic times<br />
10 ms or 1 digit<br />
(1)<br />
Operation time pick-up < 100 ms (typically 80 ms)<br />
Overshoot time < 100 ms<br />
Reset time < 100 ms<br />
(1) In reference conditions (IEC 60255-6) and df/dt < 3 Hz/s.<br />
T<br />
0<br />
time-delayed output<br />
“pick-up” signal<br />
3/33<br />
3