Parameter OPERRAT. MODE = 3-phase
Phase-Phase
Phase-Ground
If you have configured address 213 VT Connect. 3ph to Van, Vbn, Vcn or Vab,
Vbc, VGnd, you can select whether a threephase voltage function will evaluate the
phase-to-ground voltage or the phase-to-phase voltages.
When selecting phase-to-phase, these variables are derived from the phase-to-ground
voltages. The selection is, for example, important for single-pole faults. If the faulty
voltage drops to zero, the affected phase-to-ground voltage is thus zero, and the respec-
tive phase-to-phase voltages drop to the variable of a phase-to-ground voltage.
With phase-to-phase voltage connection the parameter is hidden.
NOTE
With regard to the phase-selective pickup messages, a special behavior is observed in the three-phase
voltage protection with phase-to-phase variables, because the phase-selective pickup message "Flx01
Pickup Lx" is allocated to the respective measured-value channel "Lx".
Single-phase faults:
If, for example, voltage V
A
drops to such degree that voltages V
AB
and V
A
exceed their threshold values, the
device indicates pickups “Flx01 Pickup A” and “Flx01 Pickup C”, because the undershooting was detected in
the first and third measured-value channel.
Two-phase faults:
If, for example, voltage V
AB
drops to such degree that its threshold value is reached, the device then indi-
cates pickup "Flx01 Pickup A", because the undershooting was detected in the first measured-value
channel.
Table 2-18 Parameter in the Setting Dialog "Measurement Procedure", Mode of Operation 1-phase
Parameter OPERRAT. MODE = 1-phase
Parameter MEAS. QUANTITY = Current or Voltage
Parameter
MEAS. METHOD
Fundamental
Only the fundamental harmonic is evaluated, higher harmonics are suppressed. This is
the standard measurement procedure of the protection functions.
True RMS
The “True” RMS value is determined, i.e. higher harmonics are evaluated. This procedure
is applied, for example, if an overload protection element must be realized on the basis of
a current measurement, as the higher harmonics contribute to thermal heating.
Parameter MEAS. QUANTITY = Current
Parameter CURRENT
Ia
Ib
Ic
In
In sensitive
In2
It is determined which current-measuring channel must be evaluated by the function.
Depending on the device version, either IN (normal-sensitive ground current input), INS
(sensitive ground current input) or IN2 (second ground current connected to the device)
can be selected.
If parameter 251 is set to A,G2,C,G; G2->B, the setting ΙN refers to the current at the
second current (ΙN2). The setting ΙNS refers to the sensitive ground current at the fourth
current input.
If parameter 251 is set to A,G2,C,G; G->B, the setting ΙN2 refers to the current at the
second current (ΙN2). The setting ΙNS or ΙNS refers to the sensitive or highly sensitive
ground current at the fourth current input.
Parameter MEAS. QUANTITY = Voltage
Parameter VOLTAGE
Functions
2.18 Flexible Protection Functions
248 SIPROTEC 4, 7SJ80, Manual
E50417-G1140-C343-A8, Edition 12.2017
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