Manual 37138C
ESDR 4T - Current Differential Protection Relay
© Woodward
Page 31/46
Modifying the Tripping Characteristic
Release value
Is/In X=000%
Trigger Value I
S
/I
N
(X2)
50 to 300 %
Definition of the threshold characteristic for the monitoring of levels 1 and 2.
This value determines the horizontal position (X2 coordinates of points P [X2/Y1]
and P [X2/Y2]) of the significant point on the trip and warning characteristic curve.
Diff. current 1
Id/In Y=000%
Limit value I
d
<I
N
(Monitoring level 1, Y1)
0 to 300 %
This value determines the vertical position (Y1 coordinate) of the significant point
P [X2/Y1] on the warning characteristic curve (monitoring step 1). The horizontal
position is identical to the tripping characteristic. The warning limit value is usually
set lower than the tripping limit value.
Diff. current 1
Delay 00,00s
Time lag for monitoring step 1
0.02 to 99.98 s
The threshold value for the differential current 1 must be exceeded for at least the
period of time indicated in this screen for tripping to occur. This value should be
set to at least 0.08 seconds when electrical restraint of inrush current or over excita-
tion is activated.
Diff. current 2
Id/In Y=000%
Limit value I
d
<I
N
(monitoring step 2, Y2)
0 to 300 %
This value determines the vertical position (Y2-coordinate) of the significant point
P [X2/Y2] on the tripping characteristic (monitoring step 2).
Diff. current 2
T1(Id<In) 00,00s
Time lag I
d
<I
N
(monitoring step 2)
0,02 to 99,98 s
The threshold value for the differential current 2 must be exceeded for at least the
period of time indicated in this screen for tripping to occur. The set time applies to
differential currents lower than 100 %.
Diff. current 2
T2(Id>In) 00,00s
Time lag I
d
>I
N
(monitoring step 2
[rapid trip step]
)
0,02 to 99,98 s
The threshold value for the differential current 2 must be exceeded for at least the
period of time indicated in this screen for tripping to occur. The set time applies in
the case of very large differential currents occurring which are larger than 100 %
(rapid trip step).
Diff. current
Hysteresis 000%
Differential current hysteresis
1 to 240 %
To prevent the signal relay constantly being opened and closed in the proximity of
the set threshold value, you can enter the percentage differential between the
pickup and release value (hysteresis), referring to the rated current I
N
.
