GE LPS-D, Instruction Manual, Page: 25 / 436

GE Power Management LPS-D Line Protection System 1-
7
1 PRODUCT DESCRIPTION 1.2 INTRODUCTION
1
In the LPS-D relay, the four straight lines of the quadrilateral characteristic are developed from a combination
of the following three characteristics:
1. The reactance characteristic (section 1). The tilt of the reactance characteristic is determined by the char-
acteristic timer setting. The range of this setting is 80° to 155° in 1° steps.
2. The restricted directional characteristic (sections 2 and 4)
3. The right (positive) resistive blinder (section 3)
The following definitions pertain to all the distance functions:
I
A
= phase A current at relay
I
B
= phase B current at relay
I
C
= phase C current at relay
I
0
= zero-sequence current at relay
V
A
= phase A to ground voltage at relay
V
B
= phase B to ground voltage at relay
V
C
= phase C to ground voltage at relay
X
1
= positive-sequence component of X
X
2
= negative-sequence component of X
X
M
= memory (pre-fault) value of X
Z x
1
= Zone x positive-sequence reach setting - ZxR
∠
POSSEQANG
Z x
0
= Zone x zero-sequence reach setting - ZxR
∠
ZERSEQANG
Note: The magnitudes of Zx
1
and Zx
0
are identical - these quantities differ in phase angle only.
K
0
1 = Zone 1 zero-sequence compensation factor - Z1K0
K
0
= zero-sequence compensation factor
a) REACTANCE CHARACTERISTIC
The reactance characteristic used for the ground quadrilateral is the similar as the existing negative / zero
sequence phase angle comparator reactance characteristic. The function has been modified by the addition of
a fourth comparator input (Pol. #3). The operate and polarizing signals used in this function are:
Operate: I
φ ′
Z – V
φ
Pol.# 1: I
0
Z
1
Pol.# 2: I
2
Z
1
Pol.# 3: I
1 F
Z
1
where:
I
φ ′
Z is the compensated IZ product
Z
1
is the positive sequence replica impedance
V
φ
is the phase to ground voltage
I
0
is the zero sequence current component
I
2
is the negative sequence current component, referenced to the proper phase.
I
1 F
is the fault component of the positive sequence current component, referenced to the proper
phase. The pre-fault load current is removed from this quantity.
All zones of ground reactance characteristics will have a characteristic timer with a pickup range of 90° to 155°
in 1° steps. The characteristic timer will be used to “tilt” the reactance characteristic (Tent) to prevent overreach
on non-homogeneous systems, as shown below in Figure 1–2: TENT CHARACTERISTIC. Note that the “tent”