Hitachi Relion 670 Series Applications Manual page 209

1MRK506375-UEN Rev. N
we accept a synchrocheck with a long operation time and high sensitivity regarding the frequency
difference. The phase angle difference setting can be set for steady state conditions.
Another example is the operation of a power network that is disturbed due to a fault event: After the
fault clearance a highspeed auto-reclosing takes place. This can cause a power swing in the network
and the phase angle difference may begin to oscillate. Generally, the frequency difference is the time
derivative of the phase angle difference and typically oscillates between positive and negative
values. When the circuit breaker needs to be closed by auto-reclosing after fault-clearance some
frequency difference should be tolerated. But if a big and increasing phase angle difference is
allowed at the same time, there is some risk in auto-reclosing. In this case it is safer to close when
the phase angle difference is smaller.
To fulfill the requirements above, the synchrocheck function is provided with separate settings for
steady (Manual) conditions and operation under disturbed conditions (Auto).
UHighBusSC > 10 - 120 % of GblBaseSelBus
UHighLineSC > 10 - 120 % of GblBaseSelLine
UDiffSC < 0.02 – 0.50 p.u.
PhaseDiffM < 5 - 90 degrees
PhaseDiffA < 5 - 90 degrees
FreqDiffM < 3 - 1000 mHz
FreqDiffA < 3 - 1000 mHz
IEC16000122 V1 EN-US
Figure 73:
12.1.2.3 Energizing check
The main purpose of the energizing check function is to facilitate the controlled re-connection of
disconnected lines and buses to energized buses and lines.
The energizing check function measures the bus and line voltages and compares them to both high
and low threshold values. The output is given only when the actual measured conditions match the
set conditions. Figure
energized. The line between CB A and CB B is energized (DLLB) from substation 1 via the circuit
breaker A and energization of station 2 is done by CB B energization check device for that breaker
DBLL. (or Both).
Railway application RER670
Application manual
SynchroCheck
Principle for the synchrocheck function
74 shows two substations, where one (1) is energized and the other (2) is not
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Bus voltage
Fuse fail
Line voltage
Fuse fail
Section 12
Control
Line
reference
voltage
IEC16000122-1-en.vsdx
M12310-3 v12
203