Rockwell Automation 865 Differential Protection Relay User Manual
Page 89
Protection Functions
3-45
865-UM001A-EN-P – July 2009
Figure 3.30 –Inverse Delay of type RI
Figure 3.31 – Inverse Delay of type RXIDG
Parameter Setting using IEC, IEEE and IEEE2 Equations
This mode is activated by setting delay type to ‘Parameters’, and then
editing the delay function constants, i.e. the parameters A ... E. The idea
is to use the standard equations with one’s own constants instead of
the standardized constants as in the previous chapter.
Example for GE-IAC51 delay type inverse:
k
=
0.50
I
=
4
pu
I
pickup
= 2
pu
A
=
0.2078
B
=
0.8630
C
=
0.8000
D
=
–0.4180
E
=
0.1947
37
.
0
8
.
0
2
4
1947
.
0
8
.
0
2
4
4180
.
0
8
.
0
2
4
8630
.
0
2078
.
0
5
.
0
3
2
=
⎥
⎥
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎢
⎢
⎣
⎡
⎟
⎠
⎞
⎜
⎝
⎛ −
+
⎟
⎠
⎞
⎜
⎝
⎛ −
−
+
⎟
⎠
⎞
⎜
⎝
⎛ −
+
⋅
=
t
The operation time in this example will be 0.37 seconds. The
resulting time/current characteristic of this example matches quite
well with the characteristic of the old electromechanical IAC51
induction disc relay.