4.5.3.3
Functionality
The residual overvoltage protection function 59N, 59G is used in distribution networks
where the residual overvoltage can reach non-acceptable levels in, for example, high
impedance grounding.
The function picks up when the residual voltage exceeds the set limit. 59N, 59G operates
with the definite time (DT) characteristic.
The function contains a blocking functionality. It is possible to block function outputs, the
definite timer or the function itself, if desired.
4.5.3.4
Operation principle
The function can be enabled and disabled with the
Operation
setting. The corresponding
parameter values are “Enable” and “Disable”.
The operation of 59N, 59G can be described by using a module diagram. All the modules
in the diagram are explained in the next sections.
GUID-852F56DB-266E-4CB8-BC58-01D4BA605FD0-ANSI V1 EN
Figure 314:
Functional module diagram
Level detector
The residual voltage is compared to the set
Pickup value
. If the value exceeds the set
Pickup value
, the level detector sends an enable signal to the timer. The residual voltage
can be selected with the
VG/V0 Select
setting. The options are "Measured VG" and
"Calculated V0". If "Measured VG" is selected, the voltage ratio for VG-channel is given
in the global setting
Configuration/Analog inputs/Voltage (VG,VT)
. If "Calculated
V0" is selected, the voltage ratio is obtained from phase-voltage channels given in the
global setting
Configuration/Analog inputs/Voltage (3V,VT)
.
Example 1:
VG is measured from the 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
Section 4
1MAC059074-MB A
Protection functions
628
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: ......