I
L
is a shorter notation for the measured load current; it is to be used instead of the
three-phase quantities Ia, Ib, Ic or the two-phase quantities Ii and Ij, or single-phase
current Ii.
Also note that for simplicity, the Parameter Setting menu structures
included in the following procedure are referred to universally as
VCP1, for example, Main menu/Settings/Setting Group N/Control/
TransformerVoltageControl(ATCC,90)/TR1ATCC:x/TR8ATCC:x/
Time/t1 and t2l.
For cases where single-mode voltage control is implemented, the Parameter Setting
menu structure includes TR1ATCC:1 instead of the parallel designator TR8ATCC:1.
13.10.3.1 Secondary test
SEMOD175185-145 v5
The voltage control function performs basic voltage regulation by comparing a
calculated load voltage (V
L
) against a voltage range defined by setting VDeadband
(with upper and lower limits V2 and V1 respectively). The calculated load voltage V
L
represents the secondary transformer bus voltage V
B
adjusted for Load drop
compensation (LDC) where enabled in settings.
Note that when LDC is disabled, V
B
equals V
L
.
When the load voltage V
L
stays within the interval between V1 and V2, no action will
be taken.
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.
13.10.3.2 Check the activation of the voltage control operation
SEMOD175185-537 v8
Section 13 1MRK 502 073-UUS A
Testing functionality by secondary injection
260 Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Commissioning manual
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