TRIP
Neutral
admittance
calculation
BLOCK
PICKUP
IG
VG
RELEASE
t
Timer
Operation
characteristics
Blocking
logic
GUID-1C8D95FA-FA08-4869-B74B-40D2096F160F V1 EN
Figure 175:
Functional module diagram
Neutral admittance calculation
The residual current can be selected from the
IG or I0
setting. The setting options are
"Measured IG" and "Calculated I0". If "Measured IG" is selected, the current ratio for IG-
channel is given in
Configuration/Analog inputs/Current (IG,CT)
. If "Calculated I0"
is selected, the current ratio is obtained from phase-current channels given in
Configuration/Analog inputs/Current (3I,CT)
.
Respectively, the residual voltage can be selected from the
Vg or V0
setting. The setting
options are "Measured VG" and "Calculated V0". If "Measured VG" is selected, the
voltage ratio for VG-channel is given in
Configuration/Analog inputs/Voltage
(VG,VT)
. If "Calculated V0" is selected, the voltage ratio is obtained from phase-voltage
channels given in
Configuration/Analog inputs/Voltage (3V,VT)
.
Example 1
: VG is measured from open-delta connected VTs (20/sqrt(3) kV : 100/sqrt(3)
V:100/3 V). In this case, "Measured VG" is selected. The nominal values for residual
voltage is obtained from the VT ratios entered in Residual voltage VG:
Configuration/
Analog inputs/Voltage (VG,VT)
: 11.547 kV : 100 V. The residual voltage pickup value
of 1.0 × Vn corresponds to 1.0 × 11.547 kV = 11.547 kV in the primary.
Example 2
: V0 is calculated from phase quantities. The phase VT-ratio is 20/sqrt(3) kV :
100/sqrt(3) V. In this case, "Calculated V0" is selected. The nominal value for residual
voltage is obtained from the VT ratios entered in Residual voltage V0 :
Configuration/
Analog inputs/Voltage (3V,VT)
: 20.000kV : 100V. The residual voltage pickup value
of 1.0 × Vn corresponds to 1.0 × 20.000 kV = 20.000 kV in the primary.
In case, if "Calculated V0" is selected, the residual voltage nominal value
is always phase-to-phase voltage. Thus, the valid maximum setting for
residual voltage pickup value is 0.577 × Vn. The calculated V0 requires
that all three phase-to-ground voltages are connected to the protection
relay. V0 cannot be calculated from the phase-to-phase voltages.
When the residual voltage exceeds the set threshold
Voltage pickup value
, a ground fault
is detected and the neutral admittance calculation is released.
Section 4
1MAC059074-MB A
Protection functions
372
615 series ANSI
Technical Manual
Summary of Contents for Relion 615 series
Page 1: ... RELION PROTECTION AND CONTROL 615 series ANSI Technical Manual ...
Page 2: ......
Page 39: ...Section 17 Glossary 1181 Table of contents 615 series ANSI 33 Technical Manual ...
Page 40: ...34 ...
Page 64: ...58 ...
Page 216: ...210 ...
Page 884: ...878 ...
Page 1038: ...1032 ...
Page 1136: ...1130 ...
Page 1172: ...1166 ...
Page 1180: ...1174 ...
Page 1186: ...1180 ...
Page 1192: ...1186 ...
Page 1193: ...1187 ...
Page 1194: ......
Page 1195: ......