Functions
2.13 Flexible Protection Functions
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
211
Table 2-12 Parameter in the Settings Dialog "Measurement Procedure", Mode of Operation 3-phase
Mode of Oper-
ation
Measured
Variable
Notes
Three-phase Current,
Voltage
Parameter
MEAS. METHOD
Setting Options
Fundamental Harmonic Only the fundamental harmonic is evaluated, higher harmon-
ics are suppressed. This is the standard measurement proce-
dure of the protection functions.
Important: The voltage threshold value is always parameter-
ized as phase-to-phase voltage independent of parameter
VOLTAGE SYSTEM.
True RMS The "true" RMS value is determined, i.e. higher harmonics
are evaluated. This procedure is applied, for example, if a
simple overload protection is to be implemented on the basis
of a current measurement, as the higher harmonics contrib-
ute to thermal heating.
Important: The voltage threshold value is always parameter-
ized as phase-to-phase voltage independent of parameter
VOLTAGE SYSTEM.
Positive sequence
system,
Negative sequence
system,
Zero sequence system
In order to implement certain applications, the positive se-
quence system or negative sequence system can be config-
ured as measurement procedure. Examples are:
- I2 (tripping monitoring system)
- U2 (voltage asymmetry)
Selecting the selection zero-sequence system enables addi-
tional zero-sequence current or zero-sequence voltage func-
tions to be implemented that operate independently of the
ground variables IN and VN, which are measured directly via
transformers.
Important: The voltage threshold value is always parameter-
ized always parameterized according to the definition of the
symmetrical components independent of parameter
VOLTAGE SYSTEM.
Current Ratio I2/I1 The ratio negative/positive sequence current is evaluated
Voltage Parameter
VOLTAGE SYSTEM
Setting Options
Phase-to-phase
Phase-to-Ground
If you have configured address 213 VT Connect. 3ph to Van,
Vbn, Vcn or Vab, Vbc, VGnd, you can select whether a 3-
phase 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 af-
fected phase-to-Ground voltage is zero, whereas the affected
phase-to-phase voltages collapse to the size of a phase-to-
Ground voltage.
With phase-to-phase voltage connections the parameter is
hidden.
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