# Definitions - GE UR Series Instruction Manual

Line differential relay.

8.2 OPERATING CONDITION CALCULATIONS
8.2 OPERATING CONDITION CALCULATIONS
2
I
= Operating parameter
op
2
I
= Restraining parameter
rest
I _L
= Local current phasor
I _R
= Remote current phasor
S 1
= Slope 1 factor
S 2
= Slope 2 factor
P
= Pickup setting
BP
= Breakpoint between 2 slopes
σ
= Dynamic correction factor for local phasor error estimated by the covariance matrix
loc
σ
= Dynamic correction factor for remote phasor error estimated by the covariance matrix
rem
I_R1
= Remote 1 current phasor
I_R2
= Remote 2 current phasor
σ
= Dynamic correction factor for remote 1 phasor error estimated by the covariance matrix
rem1
σ
= Dynamic correction factor for remote 2 phasor error estimated by the covariance matrix
rem2
where (see Section 8.1.18)
σ
SumOfSquares
=
2
I
>
op
Trip Condition:
--------- -
2
I
rest
The relays at all terminals are arranged so that current into the protected circuit is defined as 'positive flow'. This
means that on a two terminal installation with a through current flow, a given phase current angle will be different by
NOTE
180°. For this condition, the angle of the terminal with flow into the line could be 0° and the other terminal would be
180°.
The operating parameter is estimated with the following equation:
8
2
I
I _L I _R
=
+
op
The restraining parameter
condition is met:
<
1.
If
I _L
BP
and
2
then
I
2 S 1
=
rest
>
2.
If
I _L
BP
and
2
then
I
2 S 2
=
rest
<
3.
If
I _L
BP
and
8-18
(
(
Re PhaseletSum
n
2
I
op
1
;
Restraint Condition:
--------- -
2
I
rest
2
2
I
is calculated with one of the following four equations depending on which corresponding
rest
<
I _R
BP
2
2
2
2
I _L
2 S 1
I _R
2 P
+
+
<
I _R
BP
2
2
2
2
(
)
I _L
BP
2 S 1
BP
+
>
I _R
BP
L90 Line Differential Relay
) Re Phasor
(
)
(
Im PhaseletSum
+
n
n
1
2
σ
σ
+
+
loc
rem
2
2
2
2
2
S 1
I _R
2 P
+
+
+
8 THEORY OF OPERATION

## 8.2.1 DEFINITIONS

) Im Phasor
(
)
)
n
n
8.2.2 2 TERMINAL MODE
σ
σ
+
loc
rem
GE Power Management