[loblokir-090913-01.vsd, 1, en_US]
Figure 8-111 Logic Blockings
1) If transformer differential protection is available
2) If a current measurement is available
If assignment of the tap changer for the transformer side is available, the current of the upper-voltage side is
also monitored and the differential-protection pickup automatically blocks the voltage controller.
Additional Blockings for the Three-Winding Transformer Voltage Controller
The blockings described in the above sections also apply to the controlled winding of the three-winding trans-
former. In addition, the blockings for undervoltage, minimum voltage, and overcurrent are used for the meas-
urands of the uncontrolled side.
Additional Blockings for the Grid Coupling Transformer Voltage Controller
For voltage control in grid coupling transformers, the voltages and currents of both windings are always used
for the blockings.
Functional Measured Values
You can read the current status of the measured values for the two-winding, three-winding, and grid coupling
transformers at any time. The following 3 tables show you the measured values available.
Measured Values, Two-Winding Transformer
Measured Value
Description Primary Secondary % Referenced to
V act.
Current, measured positive-
sequence voltage (referenced
to phase-to-phase)
kV V Target voltage of the primary
system referenced to the rated
voltage
ΔV act.
Voltage difference between
the target voltage and the
actual voltage
kV V Voltage difference referenced
to the rated voltage of the
controlled winding
I load
Current measured load current
(positive-sequence system)
A A Load current referenced to the
rated current of the winding
V max
Maximum positive-sequence
voltage ever measured (refer-
enced to phase-to-phase)
kV V Maximum voltage of the
winding referenced to the
rated voltage of the winding
V min
Minimum positive-sequence
voltage ever measured (refer-
ence to phase-to-phase)
kV V Minimum voltage of the
winding referenced to the
rated voltage of the winding
Control Functions
8.9 Voltage Controller
SIPROTEC 5, Overcurrent Protection, Manual 1209
C53000-G5040-C017-8, Edition 07.2017
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