Hitachi Relion 670 Series Applications Manual page 208

Section 12
Control
for the phase angle difference caused if different setting values are selected for the two sides of the
breaker. This compensation has to be done with the PhaseShift setting according to Table 25.
Table 25:
SelPhase Bus
Phase L1 or Positive sequence
Phase L1 or Positive sequence
Phase L2
Phase L2
12.1.2.2 Synchrocheck
The main purpose of the synchrocheck function is to provide control over closing circuit breakers in
power networks. The purpose for providing control is to prevent the closing if the conditions of
synchronism are not detected. It is also used to prevent re-connection of two systems, which are
divided after islanding/after a two pole reclosing.
SESRSYN function block includes both the synchrocheck and the energizing features. The
energizing function allows closing when one side of the breaker is dead.
IEC16000121 V1 EN-US
Figure 72:
Figure 72
be further away, that is, a weak connection through other stations. The need for a check of
synchronization increases if the meshed system decreases since the risk of the two networks being
out of synchronization at manual or automatic closing is greater.
The synchrocheck function measures the conditions across the circuit breaker and compares against
the set limits. Output is generated only when all measured conditions are within the respective set
limits simultaneously. The check consists of:
• Live line and live bus.
• Voltage level difference.
• Frequency difference (slip). The bus and line frequency must also be within a range of ±10%
deviated from rated frequency.
• Phase angle difference.
A time delay is available to ensure that the conditions are fulfilled for a minimum period of time.
In stable power systems, the frequency difference is insignificant or zero for manually initiated closing
or closing by automatic restoration. In steady conditions, a bigger phase angle difference can be
allowed as this is sometimes the case in a long and loaded parallel power line. For this application
202
Selection of phase shift for different combinations of SelPhaseBus and SelPhaseLine
SelPhase Line
Phase L1 or Positive sequence
Phase L2
Phase L1 or Positive sequence
Phase L2
Sometimes first shot in the auto-reclosing cycle shall be performed without using
synchrocheck for railway applications. For such cases high-speed shot within the auto-
reclosing function shall be used.
Two interconnected power systems
shows two interconnected power systems. The cloud means that the interconnection can
© 2017 - 2023 Hitachi Energy. All rights reserved
PhaseShift in degrees
0
180
180
0
IEC16000121-1-en.vsdx
Railway application RER670
1MRK506375-UEN Rev. N
M12309-6 v10
Application manual