VAMP VAMP 59, Инструкции по установке, эксплуатации и настройке

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Technical description 2 Protection functions 2.7 Directional earth fault
protection I0φ> (67N)
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Modes for different network types
The available modes are:
 ResCap
This mode consists of two sub modes, Res and Cap. A digital
signal can be used to dynamically switch between these two
sub modes. This feature can be used with compensated
networks, when the Petersen coil is temporarily switched
off.
o
Res
The stage is sensitive to the resistive component of
the selected I
0
signal. This mode is used with
compensated networks (resonant grounding) and
networks earthed with a high resistance.
Compensation is usually done with a Petersen coil
between the neutral point of the main transformer
and earth. In this context "high resistance" means,
that the fault current is limited to be less than the
rated phase current. The trip area is a half plane as
drawn in Figure 2.7-2. The base angle is usually set
to zero degrees.
o
Cap
The stage is sensitive to the capacitive component of
the selected I
0
signal. This mode is used with
unearthed networks. The trip area is a half plane as
drawn in Figure 2.7-2. The base angle is usually set
to zero degrees.

Sector
This mode is used with networks earthed with a small
resistance. In this context "small" means, that a fault
current may be more than the rated phase currents. The
trip area has a shape of a sector as drawn in Figure 2.7-3.
The base angle is usually set to zero degrees or slightly on
the lagging inductive side (i.e. negative angle).
 Undir
This mode makes the stage equal to the undirectional stage
I
0
>. The phase angle and U
0
amplitude setting are
discarded. Only the amplitude of the selected I
0
input is
supervised.
Input signal selection
Each stage can be connected to supervise any of the following
inputs and signals:
 Input I
01
for all networks other than rigidly earthed.
 Calculated signal I
0Calc
for rigidly and low impedance
earthed networks. I
0Calc
= I
L1
+ I
L2
+ I
L3
= 3I
0
.