each activated external command signal, and a new closing-command sequence
cannot be started until the external command signal is reset and reactivated. The
SYNC_INPRO output is active when the closing-command sequence is in progress
and it is reset when the CL_COMMAND input is reset or
Maximum Syn time
has
elapsed.
Bypass mode
SECRSYN can be set to the bypass mode by setting the parameters
Synchrocheck
mode
and
Live dead mode
to "Off" or alternatively by activating the BYPASS input.
In the bypass mode, the closing conditions are always considered to be fulfilled by
SECRSYN. Otherwise, the operation is similar to the normal mode.
Voltage angle difference adjustment
In application where the power transformer is located between the voltage
measurement and the vector group connection gives phase difference to the
voltages between the high- and low-voltage sides, the angle adjustment can be
used to meet synchronism.
Figure 850: Angle difference when power transformer is in sychrocheck zone
The vector group of the power transformer is defined with clock numbers, where
the value of the hour pointer defines the low-voltage-side phasor and the high-
voltage-side phasor is always fixed to the clock number 12, which is same as zero.
The angle between clock numbers is 30 degrees. When comparing phase angles,
the U_BUS input is always the reference. This means that when the Yd11 power
transformer is used, the low-voltage-side voltage phasor leads by 30 degrees or
1MRS759142 F
Control functions
REX640
Technical Manual
1551
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