Functions
2.17 Flexible Protection Functions
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
290
Table 2-22
Parameter in the Setting 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 harmonics
are suppressed. This is the standard measurement procedure
of the protection functions.
Important: The voltage threshold value is always parameterized
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 an over-
load protection element must be realized on the basis of a
current measurement, as the higher harmonics contribute to
thermal heating.
Important: The voltage threshold value is always parameterized
as phase-to-phase voltage independent of parameter
VOLTAGE SYSTEM.
Positive Sequence
System,
Negative Sequence
System,
Zero Sequence System
In order to realize certain applications, the positive sequence
system or negative sequence system can be configured as
measurement procedure. Examples are:
- I2 (tripping monitoring system)
- U2 (voltage asymmetry)
Via the selection zero-sequence system, additional zero-se-
quence current or zero-sequence voltage functions can be re-
alized that operate independent of the ground variables IE and
UE, which are measured directly via transformers.
Important: The voltage threshold value is always parameterized
always parameterized according to the definition of the sym-
metrical components independent of parameter VOLTAGE
SYSTEM.
Current
Ratio
I
2/
I
1
The ratio negative/positive sequence current is evaluated
Voltage Parameter
VOLTAGE SYSTEM
Setting Options
Phase-to-phase
Phase-to-ground
If phase-to-ground voltages are connected to the device (see
parameter address 213 VT Connect. 3ph), it can be selected
whether a three-phase operating voltage function must evalu-
ate the phase-to-ground or phase-to-phase voltages. When se-
lecting phase-to-phase, these variables are derived from the
phase-to-ground voltages. The selection is, for example, im-
portant for single-pole faults. If the faulty voltage drops to zero,
the affected phase-to-ground voltage is thus zero, and the re-
spective phase-to-phase voltages drop to the variable of a
phase-to-ground voltage.
With phase-to-phase voltage connections the parameter is
hidden.
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