# GE UR Series Instruction Manual Page 293

Line differential relay.

8 THEORY OF OPERATION
2
2
I
2 S 1
I _L
then
=
rest
>
>
4.
If
I _L
BP
and
I _R
2
2
2
(
then
I
I _L
BP
=
rest
b) 3 TERMINAL MODE
Operating conditions are estimated with the following equation:
2
I
I _L I _R1 I _R2
=
+
+
op
2
I
is calculated with one of the following 8 equations depending on which corresponding condition is met:
rest
<
<
1.
If
I _L
BP
and
I _R1
4
2
2
(
(
then
I
-- - S 1
I _L
=
rest
3
>
<
2.
If
I _L
BP
and
I _R1
4
2
2
(
(
(
I
=
-- - S 2
I _L
rest
3
2
2
-- - σ
(
2 P
+
loc
3
>
>
3.
If
I _L
BP
and
I _R1
4
2
2
(
(
(
I
-- - S 2
I _L
=
rest
3
2
2
-- - σ
(
2 P
+
loc
3
>
>
I _L
BP
I _R1
4.
If
and
4
2
2
(
(
(
I
=
-- - S 2
I _L
rest
3
2
2
-- - σ
(
2 P
+
loc
3
<
>
I _L
BP
I _R1
5.
If
and
4
2
2
(
(
I
-- - S 1
I _L
=
rest
3
2
2
-- - σ
(
2 P
+
loc
3
<
<
6.
If
I _L
BP
and
I _R1
4
2
2
(
(
I
-- - S 1
I _L
=
rest
3
2
2
-- - σ
(
2 P
+
loc
3
GE Power Management
2
2
2
2
(
)
2 S 2
I _R
+
BP
+
2
BP
2
2
2
)
(
)
2 S 2
I _R
BP
4 S 1
+
+
2
<
BP
and
I _R2
BP
2
2
2
2
)
(
)
(
S 1
I _R1
S 1
+
+
<
BP
and
I _R2
BP
, then
2
2
2
2
)
)
(
)
BP
+
S 1
I _R1
σ
σ
)
+
+
rem1
rem2
<
BP
and
I _R2
BP
, then
2
2
2
2
)
)
(
(
BP
S 2
I _R1
+
σ
σ
)
+
+
rem1
rem2
>
BP
I _R2
BP
and
, then
2
2
2
2
)
)
(
(
BP
+
S 2
I _R1
σ
σ
)
+
+
rem1
rem2
>
BP
I _R2
BP
and
, then
2
2
2
2
)
(
(
)
)
S 2
I _R1
BP
+
σ
σ
)
+
+
rem1
rem2
>
BP
and
I _R2
BP
, then
2
2
2
2
)
(
)
(
S 1
I _R1
S 2
+
+
σ
σ
)
+
+
rem1
rem2
L90 Line Differential Relay
8.2 OPERATING CONDITION CALCULATIONS
2
2
2
σ
σ
S 1
2 P
BP
+
+
+
loc
2
2
2
σ
σ
BP
2 P
+
+
+
loc
2
2
2
)
)
-- - σ
(
σ
I _R2
2 P
+
+
+
loc
rem1
3
2
2
2
2
(
)
(
+
S 1
I _R2
+
S 1
BP
2
2
2
)
)
(
)
(
BP
S 1
I _R2
2 S 1
+
+
2
2
2
)
)
(
(
BP
+
S 2
I _R2
BP
2
2
2
(
(
)
)
(
S 2
I _R2
BP
2 S 1
+
+
2
2
2
2
(
)
)
(
I _R2
BP
S 1
BP
+
rem
rem
σ
)
+
rem2
)
)
+
2
2
)
)
BP
+
2
2
2
)
)
(
)
)
+
3 S 1
BP
+
2
2
)
)
BP
+
)
)
+
8
8-19

L90