Eaton EDR-5000 Nstallation, Operation And Maintenance Manual page 644

The sync-check module is able to check the synchronization of two electrical systems (system-to-system) or between a
generator and an electrical system (generator-to-system). For paralleling two electrical systems, the station frequency,
voltage, and phase angle should be exactly the same as the utility grid. Whereas the synchronization of a generator to
a system can be done with a certain slip-frequency, depending on the size of the generator used. Therefore the
maximum breaker closing time has to be taken into consideration. With the set breaker closing time, the sync-check
module is able to calculate the moment of synchronization and gives the paralleling release.
The sync-check element measures the three phase-to-neutral voltages » VA« , » VB«, and » VC« or the three phase-to-
phase voltages » VAB« , » VBC«, and » VCA« of the generator busbar. The line voltage Vx is measured by the fourth
voltage input. If all synchronous conditions are fulfilled (i. e.: ΔV [VoltageDiff], ΔF [SlipFrequency], and
Δφ [AngleDiff]) are within the limits, a signal will be issued that both systems are synchronous. An advanced Close
Angle Evaluator function takes the breaker closing time into consideration.
Synchronization Modes
When paralleling two systems, it has to be verified that the system-to-
system mode is selected. Paralleling two systems in generator-to-system
mode can cause severe damage!
Working Principle Sync-check (Generator-to-System)
(Please refer to the block diagram on next page.)
EDR-5000
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IM02602007E
644