• The voltages V-Line and V-Bus are higher than the set values for VHighBusSynch
and VHighLineSynch of the respective base voltages GblBaseSelBus and
GblBaseSelLine.
• The difference in the voltage is smaller than the set value of VDiffSynch.
• The difference in frequency is less than the set value of FreqDiffMax and larger than
the set value of FreqDiffMin. If the frequency is less than FreqDiffMin the
synchronism check is used and the value of FreqDiffMin must thus be identical to the
value FreqDiffM resp FreqDiffA for synchronism check function. The bus and line
frequencies must also be within a range of ±5 Hz from the rated frequency. When the
synchronizing option is included also for autoreclose there is no reason to have
different frequency setting for the manual and automatic reclosing and the frequency
difference values for synchronism check should be kept low.
• The frequency rate of change is less than set value for both V-Bus and V-Line.
• The difference in the phase angle is smaller than the set value of CloseAngleMax.
• The closing angle is decided by the calculation of slip frequency and required pre-
closing time.
The synchronizing function compensates for the measured slip frequency as well as the
circuit breaker closing delay. The phase angle advance is calculated continuously. The
calculation of the operation pulse sent in advance is using the measured SlipFrequency
and the set tBreaker time. To prevent incorrect closing pulses, a maximum closing angle
between bus and line is set with CloseAngleMax. Table
46 below shows the maximum
settable value for tBreaker when CloseAngleMax is set to 15 or 30 degrees, at different
allowed slip frequencies for synchronizing. To minimize the moment stress when
synchronizing near a power station, a narrower limit for the CloseAngleMax needs to be
used.
Table 46: Dependencies between tBreaker and SlipFrequency with different CloseAngleMax values
tBreaker
[s] (max settable value)
with
CloseAngleMax
= 15 degrees
[default value]
tBreaker
[s] (max settable value) with
CloseAngleMax
= 30 degrees [max
value]
SlipFrequency [Hz]
(BusFrequency -
LineFrequency)
0.040
0.080 1.000
0.050 0.100 0.800
0.080 0.160 0.500
0.200 0.400 0.200
0.400 0.810 0.100
1.000 0.080
0.800 0.050
1.000 0.040
The reference voltage can be phase-neutral A, B, C or phase-phase A-B, B-C, C-A or
positive sequence (Require a three phase voltage, that is VA, VB and VC) . By setting the
Section 15 1MRK 506 369-UUS -
Control
634 Line distance protection REL670 2.2 ANSI
Application manual
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