Fuse fail
Fuse fail Line Voltage
Line Bus Voltage
Line
reference
voltage
Bus voltage
52
ANSI10000079-2-en.vsd
SynchroCheck
VHighBusSC > 50 – 120% of GblBaseSelBus
VHighLineSC >50 – 120% of GblBaseSelLine
VDiffSC < 0.02 – 0.50 p.u.
PhaseDiffM < 5 – 90 degrees
PhaseDiffA < 5 – 90 degrees
FreqDiffM < 3 – 1000 mHz
FreqDiffA < 1000 mHz
ANSI10000079 V2 EN
Figure 299: Principle for the synchronism check function
15.1.2.3 Energizing check
The main purpose of the energizing check function is to facilitate the controlled re-
connection of disconnected lines and buses to energized buses and lines.
The energizing check function measures the bus and line voltages and compares them to
both high and low threshold values. The output is given only when the actual measured
conditions match the set conditions. Figure 300 shows two substations, where one (1) is
energized and the other (2) is not energized. The line between CB A and CB B is energized
(DLLB) from substation 1 via the circuit breaker A and energization of station 2 is done
by CB B energization check device for that breaker DBLL. (or Both).
1MRK 506 369-UUS - Section 15
Control
Line distance protection REL670 2.2 ANSI 637
Application manual
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