sepam 20 user manual - Schneider Electric

Protection functions Neutral voltage displacement
ANSI code 59N
PCRED301005EN - 06/2008
Operation
The protection function picks up if the residual voltage V0 is above a Vs0 set point,
with V0 =
V1 + V2 + V3 ,
b it includes a definite time delay T
b the residual voltage is either calculated from the 3 phase voltages or measured by
an external VT.
DE50249
Block diagram
Characteristics
Vs0 set point
Setting 2 % Unp to 80 % Unp if Vns0 (2) = sum of 3Vs
2 % Unp to 80 % Unp if Vns0 (2) = Uns/3
5 % Unp to 80 % Unp if Vns0 (2) = Uns/3
Accuracy (1) ±2 % or ±0.005 Unp
Resolution 1 %
Drop-out/pick-up ratio 97 % ±1 %
Time delay T
Setting 50 ms to 300 s
Accuracy (1) ±2 %, or ±25 ms
Resolution 10 ms or 1 digit
Characteristic times
Operation time pick-up < 55 ms
Overshoot time < 35 ms
Reset time < 55 ms
(1) In reference conditions (IEC 60255-6).
(2) Vns0 is one of the general settings.
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