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2 Functions
2.7
Circuit breaker synchronisation
50
With version V 4.2, the synchronisation function for circuit breakers is also available in
Bay Processing Unit 6MD665. Synchronisation is an order option. It can be parame-
terised if the seventh digit of the order number is 1 or 5.
In contrast to the bay controller, the PCD can output the switching command via the
process bus as well.
In this operating mode, a maximum frequency difference of 100 mHz is allowed for
closing.
Note
®
DIGSI
does not check this, i.e. it is possible to enter larger values. The limitation
depends on the least possible runtime fluctuations of the process bus. The runtime of
the command at the process bus should be measured. Information on this is found at
the end of the chapter. The determined runtime of the command must then be added
to any existing circuit breaker operating time in the System data tab. In this way, the
runtime in the (more critical) area of the asynchronous network can be taken into
account. In the synchronous network operating area, it is not possible to take this into
account. It is, however, not necessary.
Command output is also possible via the binary outputs of the Bay Processing Unit.
Larger frequency differences are also permissible here.
The measured values are acquired via analogue direct transformer inputs. The mea-
sured values from the process bus are RMS values and therefore cannot be used for
synchronisation.
If the synchronisation function of the device is active, the device can check whether
the synchronisation conditions of both subnetworks are fulfiled (synchrocheck) when
the circuit breaker is closed.
The device distinguishes between synchronous and asynchronous networks and
reacts differently on the connection.
Synchronous systems exhibit small differences regarding phase angle and voltage
modulus. The circuit breaker operating time does not need to be considered.
On the contrary, asynchronous networks include bigger differences and the time
window for closing is passed more quickly. Consequently, the circuit breaker operating
time must be considered in this case. The control command is automatically pre-dated
by this time in order to ensure that the circuit breaker contacts close exactly at the right
time. The automation functions enabled in the device allow to automatically use
various reference voltages of the active busbar for synchronisation (whereby the indi-
vidual reference voltage depends on the isolator position). It is possible to save and
hold available for operation maximally eight different setting groups for the synchroni-
sation function. In this way, it is possible to consider the various features of several
circuit breakers.
The synchronisation groups six to eight differ from the groups one to five essentially
due to the connection of the voltage transformers. Various connection examples can
be found in the Appendix.
6MD665 Manual
C53000-G1876-C103-3
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