Siemens siprotec SJ62 User Manual page 270

Table 2-20 Parameters in dialog box "Measurement Method", 3-phase operation
Operating Measured
Mode Quantity
3-phase Current,
Voltage
Voltage
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
Parameter
MEAS. METHOD
Setting Options
Fundamental wave
True RMS
Positive sequence system,
Negative sequence system,
Zero-sequence system
Parameter
VOLTAGE SYSTEM
Setting option
Phase-to-phase
Phase-to-ground
2.17 Flexible Protection Functions (7SJ64 only)
Only the fundamental wave is evaluated, harmonics are sup-
pressed. This is the standard measurement method of the pro-
tection functions.
Attention: The voltage threshold value does not depend on the
parameter VOLTAGE SYSTEM and is always configured as
phase-to-phase voltage.
The "true" r.m.s value is determined, i.e. harmonics are evalu-
ated. This procedure is used for, example, if a simple overload
protection is realized on the basis of a current measurement
since harmonics contribute to thermal heating.
Attention: The voltage threshold value does not depend on the
parameter VOLTAGE SYSTEM and is always configured as
phase-to-phase voltage.
In order to implement certain applications, it is possible to
enable either the positive or the negative sequence system as
measurement method. Examples are:
- I2 (negative sequence protection)
- V2 (voltage asymmetry)
If the zero sequence system is selected, additional zero-
current or zero-voltage functions can be implemented that work
independently of the ground quantities IN and VN measured di-
rectly via transformers.
Attention:The parameterization of the voltage threshold
depends on the parameter VOLTAGE SYSTEM:
- VOLTAGE SYSTEM = Phase-to-phase:sym. component * √3
- VOLTAGE SYSTEM = Phase-to-ground:sym. component * 3
If phase-to-ground voltages are connected to the device (see
setting 213 VT Connect. 3ph), the user can select whether a 3-
phase voltage function should evaluate the phase-to-ground or
the phase-to-phase voltages. If phase-to-phase is selected,
these values are calculated from the phase-to-ground voltag-
es. This selection is significant, e.g. for single-phase faults. If
the faulted voltage breaks down to zero, the affected phase-to-
ground voltage is zero, whereas the affected phase-to-phase
voltages collapse to the amount of a phase-to-ground voltage.
The parameter is hidden if phase-to-phase voltages are con-
nected.
Notes
268