Siemens SIPROTEC 4 User Manual page 275

Table 2-21
Parameter OPERRAT. MODE = 3-phase
Parameter MEAS. QUANTITY = Current or Voltage
Parameter MEAS. METHOD
Fundamental
True RMS
Positive seq.,
Negative seq.,
Zero sequence
Parameter MEAS. QUANTITY = Current
Parameter MEAS. METHOD
Ratio I2/I1
Parameter MEAS. QUANTITY = Voltage
Parameter VOLTAGE
SYSTEM
Phase-Phase
Phase-Ground
SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016
Parameter in the Setting Dialog "Measurement Procedure", Mode of Operation 3-phase
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. If parameter VOLTAGE SYSTEM is selected as phase-to-ground, the voltage
threshold will be devided by √3.
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.
Important: The voltage threshold value is always parameterized as phase-to-phase
voltage. If parameter VOLTAGE SYSTEM is selected as phase-to-ground, the voltage
threshold will be devided by √3.
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 sequence current or zero
sequence voltage functions can be realized that operate independent of the ground varia-
bles IN and VN, which are measured directly via transformers.
Important: The voltage threshold is always parameterized according to the definition of
the balanced components independently of parameter VOLTAGE SYSTEM.
The ratio of the negative-sequence current to the positive-sequence current is evaluated.
Please note that the function only operates ifΙ2 or Ι1 has exceeded the threshold value
0.1 · Ι .
N
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 evaluate the phase-to-ground or 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.
Functions
2.19 Flexible Protection Functions
275