SYN5201 3BHB006714R0221 Synchronizing devices and systems

Synchronizing devices are widely used in power stations or industrial installations with their own power generating facilities,
where the generators need to be paralleled with an island line or a public line, or in power distribution systems.
Power circuit breakers may only be closed if both voltages are approximately synchronous (coincident). Otherwise, faults in
line operation, loading of the generators and, in extreme cases, damage to the generators can result.
SYNCHROTACT® 5 performs these functions safely and reliably, whether as a monitoring element for manual paralleling or as an independent fully-automatic synchronizing device.

The command generation calculates the necessary lead angle αv, by which the paralleling command must be advanced
due to closing time delay. The action ensures that the main contacts close at precisely the right time. If α reaches αv at
the same time as paralleling release (CHK RELEASE), the command is issued. Under synchronous conditions, ie,
permanent paralleling release during the adjustable monitoring time, tsup, the CMD is also issued without taking the lead angle into consideration.

SYN5201

From a synchronizing device, it is expected to close the power circuit breaker at the correct time but also that, if
required, paralleling can take place whenever permissible. Although the series connection of the output contacts of two
independently-functioning channels (dual-channel system), which is usual in synchronizing systems, greatly increases
security against incorrect paralleling, it necessarily leads to a reduction in availability.

Not every synchronizing system needs to be structured according to the above pattern. The SYNCHROTACT® 5
single-channel synchronizing devices offer a high degree of security and are often used in practice. However, security
can be significantly increased by means of dual-channel systems. It is unlikely that the two channels – of which the
hardware and software are structured differently – will have the same malfunction simultaneously. The extra cost of a
dual channel system can prove beneficial compared to the damage arising from incorrect paralleling.