GE L30 User Manual

5-182 L30 Line Current Differential System GE Multilin
5.6 GROUPED ELEMENTS 5 SETTINGS
5
where: ,
,
ECA = element characteristic angle
IG = ground current
Z_offset is the offset impedance, for which magnitude is the OFFSET setting and angle is the FWD ECA
When NEUTRAL DIR OC1 POL VOLT is set to “Measured VX”, one-third of this voltage is used in place of V_0. The following
figure explains the usage of the voltage polarized directional unit of the element.
The figure below shows the voltage-polarized phase angle comparator characteristics for a phase A to ground fault, with:
• ECA = 90° (element characteristic angle = centerline of operating characteristic)
• FWD LA = 80° (forward limit angle = the ± angular limit with the ECA for operation)
• REV LA = 80° (reverse limit angle = the ± angular limit with the ECA for operation)
The above bias should be taken into account when using the neutral directional overcurrent element to directionalize other
protection elements.
Figure 5–71: NEUTRAL DIRECTIONAL VOLTAGE-POLARIZED CHARACTERISTICS
• NEUTRAL DIR OC1 POLARIZING: This setting selects the polarizing mode for the directional unit.
– If “Voltage” polarizing is selected, the element uses the zero-sequence voltage angle for polarization. The user
can use either the zero-sequence voltage V_0 calculated from the phase voltages, or the zero-sequence voltage
supplied externally as the auxiliary voltage V_X, both from the
NEUTRAL DIR OC1 SOURCE.
Table 5–30: QUANTITIES FOR "MEASURED IG" CONFIGURATION
DIRECTIONAL UNIT
OVERCURRENT UNIT
POLARIZING MODE DIRECTION COMPARED PHASORS
Voltage
Forward –V_0 + Z_offset × IG/3 IG × 1∠ECA
I
op
= |IG|
Reverse –V_0 + Z_offset × IG/3 –IG × 1∠ECA
V_0
1
3
---
VAG VBG VCG++()zero sequence voltage==
I_0
1
3
---
IN
1
3
---
IA IB IC++()zero sequence current== =
827805A1.CDR
VAG
(reference)
VBG
VCG
–3I_0 line
3I_0 line
ECA line
–ECA line
LA
LA
LA
LA
ECA
FWD LA
line
FWD Operating
Region
REV Operating
Region
FWD LA
line
REV LA
line
REV LA
line
–3V_0 line
3V_0 line

GE L30 Specifications

General

Brand	GE
Model	L30
Category	Relays
Language	English