Settings/Setting group N/Control/TransformerVoltageControl(ATCC,90)/
TR8ATCC:x/ParCtrl
The general parallel arrangement of transformers are defined by setting TnRXOP to
Enabled or Disabled. The following rules are applicable on the settings T1RXOP –
T4RXOP.
If IED T1 and T2 are connected,
• T1RXOP shall be set to Enabled in instance 2 of TR8ATCC (90),
• T2RXOP shall be set to Enabled in instance 3 of TR8ATCC (90),
• T2RXOP and T3RXOP shall be set to Enabled in instance 1 of TR8ATCC
(90), and so on.
The parameter corresponding to the own IED must not be set.
T1RXOP should thus not be set in IED T1, T2RXOP not in IED T2,
and so on.
3. The lowest transformer number in the parallel group is by default set as the Master
– confirm that this is the case by reviewing the setting in the local HMI.
4. 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 from the master transformer in the group.
5. Review the expected time for first (t1) and subsequent (t2) tap change commands
from the master transformer in the local HMI under Main menu/Settings/Setting
group N/Control/TransformerVoltageControl(ATCC,90)/TR1ATCC:x/
TR8ATCC:x/Time/t1 and t2
6. Apply a 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 command in the Signal Matrix in PCM600 and monitoring a positive from this
output. Confirm the timing of this command correlates with the setting t1.
7. After the issue of the raise command, confirm that all follower transformers in the
group change tap in accordance with the command issued from the master
transformer.
8. Inject a voltage V
B
for the master transformer that is 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 t2.
9. Confirm that all follower transformers in the group change tap in accordance with
this command.
Circulating current voltage regulation
This instruction for confirmation of circulating current voltage regulation assumes two
transformers in the parallel group. Setting confirmation through secondary injection
requires calculation of circulating currents for each transformer based on impedance
Section 11 1MRK 504 165-UUS -
Testing functionality by secondary injection
254 Transformer protection RET670 2.2 ANSI
Commissioning manual
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