Basler Electric DGC-2020HD - Manual (Page 105)

9469300990 Rev B 95
General Breaker Closure Conditions
The following conditions apply to any breaker control configuration.
Command Agreement
A breaker will not change state if it receives conflicting commands. In other words, if an input is indicating
an open command at the same time another input is indicating a close command, the breaker will not
change state.
Dead Bus Breaker Close Arbitration
Dead bus breaker close arbitration ensures that only one machine (assigned by the system manager)
closes its breaker to a dead bus. The system manager controls generator sequencing. The unit with the
lowest numbered nonzero sequencing ID is the system manager. After a machine issues a dead bus
close request and the system manager grants it, the machine that received the grant closes its breaker to
the dead bus. Now that the bus is no longer dead, all remaining units must synchronize to the live bus.
Individual units issue dead bus close requests to the system manager when they want to close their
generator breaker and a dead bus is detected. An individual unit issues a dead bus close request when
all of the following are true:
•
The generator is stable
•
A dead bus is detected
•
A generator breaker close request is received
An individual unit with its System Type parameter set to Multiple Generator will not close its breaker onto
the dead bus unless it receives a dead bus close grant from the system manager via Ethernet
communication. The System Type parameter is found on the System Settings screen in BESTCOMSPlus.
After an individual unit issues a dead bus close request and receives a dead bus close grant from the
system manager, the unit maintains its dead bus close request unless one of the following occurs:
•
The dead bus close grant is removed by the system manager
•
The generator breaker encounters a breaker close fail
•
A generator breaker open request is received
•
The generator becomes unstable
An individual unit can close to a dead bus at any time when the System Type parameter is set to Single
Generator. This is also permitted when the System Type parameter is set to Multiple Generator and no
other generators are present on the Ethernet inter-genset communications network.
The Unit ID of the system manager can be found on the front panel of each unit and in BESTCOMSPlus.
Refer to Generator Network Status Display in the Metering chapter.
All units in the system reporting a dead bus must be visible to the system manager via Ethernet before
any dead bus close grant is issued. The system manager removes any dead bus close grant if any
machine reports the bus is not dead. A dead bus close grant is not removed by the system manager
unless the unit that received the grant removes its request or another machine reports that the bus is not
dead.
For consistent operation, all units should be set up with the same demand start/stop and sequencing
criteria. This ensures that system manager functionality is transferred accordingly as the lowest numbered
nonzero sequence ID changes in the system.
Synchronization
Synchronization is required when closing a breaker to a live bus. Bus conditions act as a supervisory
control over the synchronizing function. If synchronization is in process and either bus goes unstable,
synchronization is suspended.
The GENBRK and MAINSBRK logic blocks contain both Open and Close logic outputs that can be
configured to energize an output contact, which would in turn operate the breaker. The Breaker Hardware
screen in BESTCOMSPlus is used to set the output contact type to pulses or continuous.
DGC-2020HD Breaker Management