ABB RELION RET670, Commissioning Manual, Page: 258 / 328

1. Confirm the setting for Iblock in the local HMI under Main menu/Settings/Setting
group N/Control/TransformerVoltageControl(ATCC,91)/TR1ATCC:x/
TR8ATCC:x/TCCtrl/Iblock
2. Confirm the voltage control function response to an applied current above Iblock , by
reviewing the settings in the local HMI under Main menu/Settings/General
settings/Control/TransformerVoltageControl(ATCC,91)/TR1ATCC:x/
TR8ATCC:x/OVPartBk
. This condition may cause an alarm or total block of the
voltage control function to be displayed on the local HMI.
3. Inject a current higher than the Iblock setting and confirm the alarm or blocking
condition is present on the local HMI. If an automatic or total blocking condition
occurs, change the applied secondary voltage and confirm that no tap change
commands are issued from the associated binary outputs. This situation can also be
confirmed through reviewing the disturbance and service reports on the local HMI.
11.10.3.7 Single transformer
Load drop compensation
1. Confirm that OperationLDC is set to Enabled .
2. Confirm settings for Rline and Xline .
3. Calculate the expected load voltage V
L
(displayed as a measured value on the local
HMI) based on secondary injection of transformer secondary voltage (VB = VSet )
and rated load current (I
L
= I1Base ), in accordance with equation 108 .
V
L
= VB - (Rline + jXline) . I
L
EQUATION2081-ANSI V2 EN
(Equation 108)
where:
V
L
, I
L
= Re(I
L
) + jlm(I
L
) are complex phase quantities
When all secondary phase-to-ground voltages are available, use the positive-
sequence components of voltage and current. By separation of real and imaginary
parts:
, , , , vl re vb re rline il re xline il im
= - × + ×
EQUATION2083-ANSI V1 EN
(Equation 109)
Section 11
1MRK 504 165-UUS -
Testing functionality by secondary injection
252 Transformer protection RET670 2.2 ANSI
Commissioning manual