If V
L
< V1 or V
L
> V2, a command timer will pickup, which is constant time or inverse time defined by
setting t1 and t1Use. The command timer will trip while the measured voltage stays outside the inner
deadband (defined by setting VDeadbandInner).
If V
L
remains outside of the voltage range defined by VDeadband and the command timer expires, the
voltage control will execute a raise or lower command to the transformer tap changer. This command
sequence will be repeated until V
L
is brought back within the inner deadband range.
11.11.5.2 Check the activation of the voltage control operation
SEMOD175185-537 v10
1. Confirm Transformer Tap Control = Enable and Transformer Voltage Control = Enable
• Direct tap change control
Main menu /Settings /IED Settings /Control /TransformerTapChanger(84,⇅) /
TCMYLTC(84,⇅):x/TCLYLTC(84,⇅):x /Operation
• Automatic transformer voltage control
Main menu /Settings /IED Settings /Control /TransformerVoltageControl(90,↕) /TR1ATCC(90,
U↕):x/TR8ATCC(90, U↕||):x /General /Operation
• Enable Tap Command
Main menu /Settings /IED Settings /Control /TransformerTapChanger(84,⇅) /
TCMYLTC(84,⇅):x/TCLYLTC(84,⇅):x /EnabTapCmd
While the test set is connected to the IED but no voltage is applied, the voltage control functions
will detect an undervoltage condition that may result in an alarm or blocking of the voltage-control
operation. These conditions will be shown on the local HMI.
2. Apply the corresponding voltage
Confirm the analog measuring mode prior to undertaking secondary injection (positive sequence,
phase-to-phase, or phase-to-ground). This measuring mode is defined in the local HMI under Main
menu /Settings /IED Settings /Control /TransformerVoltageControl(90, U↕) /TR1ATCC(90,
U↕):x/TR8ATCC(90, U↕||):x /General /MeasMode
The application of nominal voltage VSet according to set MeasMode to the IEDs should cause the
alarm or blocking condition for undervoltage to reset.
11.11.5.3 Check the normal voltage regulation function
SEMOD175185-562 v7
1. Review the settings for VDeadband (based on percentage of nominal bus voltage) and calculate
the upper (V2) and lower (V1) voltage regulation limits for which a tap change command will be
issued.
2. Review the expected time for first (t1) and subsequent (t2) tap change commands from the voltage
control function on the local HMI under Main menu /Settings /IED Settings /Control /
TransformerVoltageControl(90, U↕) /TR1ATCC(90, U↕):x/TR8ATCC(90, U↕||):x /Time /t1 and t2
3. Lower the voltage 1% below V1 and wait for the issue of a Raise command from the voltage control
after the expiry of a constant or inverse time delay set by t1. Detection of this command will involve
locating the allocated binary output for a raise pulse command in the Signal Matrix in PCM600 and
monitoring a positive from this output.
4. After the issue of the raise command, return the applied voltage to VSet (nominal value).
5. Raise the voltage 1% above the upper deadband limit V2 and wait for the issue of a lower
command from the voltage control after the expiry of a constant or inverse time delay set by t1.
Section 11 1MRK 504 165-UUS Rev. J
Testing functionality by secondary injection
256 Transformer protection RET670
Commissioning manual
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