IEC07000189 V2 EN-US
Figure 116: Earth fault in Direct earthed system
8.3.3.6 Settings for two step residual overvoltage protection
M13853-21 v13
Operation
:
Off
or
On
UBase
(given in
GlobalBaseSel
) is used as voltage reference for the set pickup values. The
voltage can be fed to the IED in different ways:
1. The IED is fed from a normal voltage transformer group where the residual voltage is
calculated internally from the phase-to-earth voltages within the protection. The setting
of the analog input is given as
UBase
=Uph-ph.
2. The IED is fed from a broken delta connection normal voltage transformer group. In an
open delta connection the protection is fed by the voltage 3U0 (single input). Section
Analog inputs
in the Application manual explains how the analog input needs to be set.
3. The IED is fed from a single voltage transformer connected to the neutral point of a power
transformer in the power system. In this connection the protection is fed by the voltage
UN=U
0
(single input). Section
Analog inputs
in the Application manual explains how the
analog input needs to be set.
ROV2PTOV will measure the residual voltage corresponding to the nominal phase-to-earth
voltage for a high-impedance earthed system. The measurement will be based on the neutral
voltage displacement.
The setting parameters described below are identical for the two steps (
n
= step 1 and 2).
Therefore the setting parameters are described only once.
OperationStepn
: This is to enable/disable operation of step n.
Characteristicn:
Selected inverse time characteristic for step
n
. This parameter gives the type
of time delay to be used. The setting can be,
Definite time
or
Inverse curve A
or
Inverse curve B
or
Inverse curve C
or
Prog. inv. curve
. The choice is highly dependent of the protection
application.
Un>
: Set operate overvoltage operation value for step
n
, given as % of residual voltage
corresponding to
UBase
:
1MRK 505 370-UEN D Section 8
Voltage protection
Busbar protection REB670 215
Application manual
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