No. Information Description
2568
TapChg Down En.
Allows the tap changer to issue tap down pulses. This input can be used to
block the tap down commands if voltage in the substation has reached the
minimum value and further tap down steps can cause undervoltage.
2569
TapChg Down
Manual tap down command. Tap changer issues a single Tap down pulse if
Auto mode is OFF.
2570
AUTO Mode ON
Auto mode allows tap changer to work automatically in an SDFA system.
2575
Ext 27 UV PU
External undervoltage element pickup. Tap changer uses this input if 2577
IntVoltMeas
has value "0".
2576
Ext 59 OV PU
External overvoltage element pickup. Tap changer uses this input if 2577
IntVoltMeas
has value "0".
2577
IntVoltMeas
This input switches between two sources for overvoltage/undervoltage indi-
cations. If set to "0", inputs 2576
Ext 59 OV PU
and 2577
IntVoltMeas
are in use. If set to "1", the logic uses inputs 2581
Vmeas > Vthr
and
2582
Vmeas < Vthr
.
2578
Vol Level Crit.
Voltage dropped below the critical level. If the input 2579
VoltRedTa-
pUpEn
is high, the tap change logic issues a single tap up pulse. Input 2568
TapChg Down En.
must turn to "0" when the signal 2578
Vol Level
Crit.
is present.
2579
VoltRedTapUpEn
Input allows one single tap up pulse in voltage reduction mode if alarm
2578
Vol Level Crit.
is coming.
2583
Vmeas > Vmin
Measurement voltage is greater than minimum voltage; that is, bus is live
and tap up commands are allowed.
The capacitor bank control does not require feedback inputs from the capacitor bank. The ON and OFF
commands are monitored internally by the RS flip-flop, which provides the feedback outputs 2544
CapCmd-
Status ON
and 2545
CapCmdStat. OFF
to the control center and the rest of the system. In order to
synchronize the internal feedback with the actual capacitor bank status, 7SC80 issues one single OFF
command when initialized for the first time. The input 2558
Init OFF Enable
should be provided with a
permanent high indication. If the application employs the 7SC80 capacitor bank control function, any other
existing controllers should be disabled to avoid duplicate or opposite commands to the capacitor bank.
More indications can be found in the following information overview.
Application Example
The typical tap changer application requires a minor CFC logic to provide over-/undervoltage inputs as well as
modes of operation.
Integration with CFC is represented below, where comparator 1 compares positive sequence (or a phase-
toneutral) voltage V1 with the nominal voltage. If V1 is greater than the nominal voltage, comparator 1 issues
the signal 2581
Vmeas > Vthr
, allowing the tap changer to issue tap down commands to lower the voltage
back to the nominal value. If V1 is smaller than the nominal voltage, comparator 1 issues the signal 2582
Vmeas < Vthr
to generate tap up pulses and raise the voltage. If both V1 and the nominal voltage are
within the hysteresis value (1 % in this example), comparator 1 issues the signal 2580
Vmeas = Vthr
to stop
tap up or tap down commands from the tap changer.
Functions
2.22 Tap Changer
352 SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
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