Setting of the voltage difference between the line voltage and the bus voltage. The
difference is set depending on the network configuration and expected voltages in the
two networks running asynchronously. A normal setting is 0.10-0.15 p.u.
FreqDiffMin
The setting FreqDiffMin is the minimum frequency difference where the systems are
defined to be asynchronous. For frequency differences lower than this value, the
systems are considered to be in parallel. A typical value for FreqDiffMin is 10 mHz.
Generally, the value should be low if both synchronizing and synchrocheck functions
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.
FreqDiffMin must be set to the same value as FreqDiffM, respective
FreqDiffA for SESRSYN depending on whether the functions are used
for manual operation, autoreclosing, or both.
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.
tBreaker
The setting tBreaker shall be set to match the closing time for the circuit breaker and
must also include the possible auxiliary relays in the closing circuit. A typical setting is
80-150 ms, depending on the breaker closing time.
It is important to check that no slow logic components are used in the
configuration of the IED, as this may cause variations in the closing time.
tClosePulse
The setting for the duration of the breaker close pulse.
tMaxSynch
Section 3 1MRK504116-UUS C
IED application
596
Application manual
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