ABB Relion 650 Series Applications Manual page 122

Section 10
Control
The synchronizing function compensates for measured slip frequency as well as the circuit breaker
closing delay. The phase angle advance is calculated continuously. Closing angle is the change in
angle during the set breaker closing operate time
The reference voltage can be phase-neutral A, B, C or phase-phase A-B, B-C, C-A or positive
sequence. The bus voltage must then be connected to the same phase or phases as are chosen for
the line. If different phases voltages are used for the reference voltage, the phase shift has to be
compensated with the parameter
by the factor
three phase voltages.
10.1.2.2 Synchronism check
The main purpose of the synchronism check function is to provide control over the closing of
circuit breakers in power networks in order to prevent closing if conditions for synchronism are
not detected. It is also used to prevent the re-connection of two systems, which are divided after
islanding and after a three pole reclosing.
SESRSYN (25) function block includes both the synchronism check function and the energizing
function to allow closing when one side of the breaker is dead. SESRSYN (25) function also
includes a built in voltage selection scheme which allows adoption to various busbar
arrangements.
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ANSI04000179 V1 EN-US
Figure 41: Two interconnected power systems
Figure 41
can 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 synchronism check function measures the conditions across the circuit breaker and compares
them to set limits. Output is generated only when all measured conditions are within their 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 ±5 Hz
from rated frequency.
• Phase angle difference.
A time delay is available to ensure that the conditions are fulfilled for a minimum period of time.
116
URatio . Positive sequence selection setting requires that both reference voltages are
Single pole auto-reclosing does not require any synchronism check since the
system is tied together by two phases.
shows two interconnected power systems. The cloud means that the interconnection
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tBreaker .
PhaseShift , and the voltage amplitude has to be compensated
1MRK 505 287-UUS B
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Busbar protection REB650
Application manual
M12309-6 v8