Protective Elements
Synchronization Modes
The synchrocheck 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 synchrocheck module is able to calculate the moment of synchronization and gives the
paralleling release.
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 Synchrocheck (Generator-to-System)
(Please refer to the block diagram on next page.)
The synchrocheck element measures the three phase-to-neutral voltages »
VL1«, »VL2«, and »VL3« or the three
phase-to-phase voltages »
VL1-L2«, »VL2-L3«, and »VL3-L1« 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.
435
MRU4
DOK-HB-MRU4-2E
