Choose the setting value SeriesComp if the protected line or adjacent lines are
compensated with series capacitors. Otherwise maintain the NoSeriesComp setting value.
CVTtype
If possible, the type of capacitive voltage transformer (CVT) that is used for measurement
should be identified. Note that the alternatives are strongly related to the type of ferro-
resonance suppression circuit that is included in the CVT. There are two main choices:
Passive type
For CVTs that use a non-linear component, like a saturable inductor, to limit overvoltages
(caused by ferro-resonance). This component is practically idle during normal load and fault
conditions, hence the name ‘passive’. CVTs that have a high resistive burden to mitigate
ferro-resonance also fall in to this category.
Any
This option is primarily related to the so-called active type CVT, which uses a set of reactive
components to form a filter circuit that essentially attenuates frequencies other than the
nominal in order to restrain the ferro-resonance. The name ‘active’ refers to the fact that this
circuit is always involved during transient conditions, regardless of voltage level. This option
should also be used for types that do not fall under the other two categories, for example,
CVTs with power electronic damping devices, or if the type cannot be identified at all.
None
(Magnetic)
This option should be selected if the voltage transformer is fully magnetic.
3I0Enable_PG
This setting opens up an opportunity to enable phase-to-ground measurement for phase-
to-phase-ground faults. It determines the level of residual current (3I0) above which
phase-to-ground measurement is activated (and phase-to-phase measurement is blocked).
The relations are defined by the following equation.
0 max
3I0Enable _ PG
3
100
ph
I
I I× ³ ×
EQUATION2548-ANSI V1 EN (Equation 400)
Where:
3I0Enable_P
G
is the setting for the minimum residual current needed to enable operation in the phase-to-
ground fault loops in %
Iphmax is the maximum phase current in any of three phases
By default this setting is set excessively high to always enable phase-to-phase
measurement for phase-to-phase-ground faults. Maintain this default setting value unless
there are very specific reasons to enable phase-to-ground measurement. Please note that,
even with the default setting value, phase-to-ground measurement is activated whenever
appropriate, like in the case of simultaneous faults: two ground faults at the same time, one
each on the two circuits of a double line.
Section 8 1MRK 506 369-UUS -
Impedance protection
434 Line distance protection REL670 2.2 ANSI
Application manual
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