ABB Relion REC670, Applications Manual

Page: 326 / 658

are provided, and it is better to let the synchronizing function close, as it will close at
exactly the right instance if the networks run with a frequency difference.
To avoid overlapping of the synchronizing function and the
synchrocheck function the setting
FreqDiffMin must be set to a higher
value than used setting FreqDiffM , respective FreqDiffA used for
synchrocheck.
FreqDiffMax
The setting FreqDiffMax is the maximum slip frequency at which synchronizing is
accepted. 1/ FreqDiffMax shows the time for the vector to move 360 degrees, one turn
on the synchronoscope, and is called Beat time. A typical value for FreqDiffMax is
200-250 mHz, which gives beat times on 4-5 seconds. Higher values should be avoided
as the two networks normally are regulated to nominal frequency independent of each
other, so the frequency difference shall be small.
FreqRateChange
The maximum allowed rate of change for the frequency.
CloseAngleMax
The setting CloseAngleMax is the maximum closing angle between bus and line at
which synchronizing is accepted. To minimize the moment stress when synchronizing
near a power station, a narrower limit should be used. A typical value is 15 degrees.
tBreaker
The tBreaker shall be set to match the closing time for the circuit breaker and should
also include the possible auxiliary relays in the closing circuit. It is important to check
that no slow logic components are used in the configuration of the IED as there then
can be big variations in closing time due to those components. Typical setting is
80-150 ms depending on the breaker closing time.
tClosePulse
The setting for the duration of the breaker close pulse.
tMaxSynch
The setting tMaxSynch is set to reset the operation of the synchronizing function if the
operation does not take place within this time. The setting must allow for the setting of
FreqDiffMin , which will decide how long it will take maximum to reach phase
equality. At the setting of 10 mHz, the beat time is 100 seconds and the setting would
thus need to be at least
tMinSynch plus 100 seconds. If the network frequencies are
Section 14
1MRK 511 401-UUS A
Control
320 Bay control REC670 2.2 ANSI
Application manual