Basler Electric DGC-2020 - Manual (Page 99)

NOTES
When using the DGC-2020 synchronizer, it is recommended that local DGC-
2020 relay outputs be used for breaker closing commands to minimize the
possibility of closures outside of desired breaker closing angles.
If remote (CEM-2020) outputs are to be used for breaker close commands, it is
recommended that the anticipatory synchronizer type be used, and the breaker
close wait time be adjusted to account for possible CEM-2020 output delays
(typically 50 ms) to achieve desired breaker closing angles.
If the synchronizer does not seem to operate properly, refer to Section 8, Maintenance and
Troubleshooting.
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 system
manager is the unit with the lowest numbered nonzero sequencing ID. 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:
1. The generator is stable
2. A dead bus is detected
3. 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. The LSM-
2020 provides Ethernet communication between the DGC-2020 and the network. 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 or an LSM-2020 is not providing Ethernet communication between the DGC-2020 and the
network.
The Unit ID of the system manager can be found on the front panel of each unit and in BESTCOMSPlus
®.
Refer to Section 2, Human-Machine Interface, Display Operation, Generator Network Status Display.
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 manger functionality is transferred accordingly as the lowest numbered
nonzero sequence ID changes in the system.
Event Recording
An event log retains history of system events in nonvolatile memory. Fifty event records are retained and
each record contains a time stamp of the first and last event occurrence, and the number of occurrences
for each event. In addition, each record contains details of the time, date, and engine hours for the most
recent 30 occurrences of the event. The number of occurrences stops incrementing at 99. If an event
occurs which is of a type that differs from those in the 50 records in memory, the record that has the
9400200990 Rev X DGC-2020 Functional Description 3-25