Basler Electric DGC-2020HD - Manual (Page 307)

9469300990 Rev B 297
DGC-2020HD Maintenance and Troubleshooting
contacts to remove the DGC-2020HD from the load share system when the generator breaker
is closed.
Step 10: If it appears that something is driving the load share line but it is not the DGC-2020HD on one
of the non-running units, search for an external device that is driving or loading down the load
share lines.
Step 11: Repeat the preceding 3 steps for each machine.
Load Sharing Works Correctly, but a Single Unit Slows Down
With all units running, load sharing works correctly, but a single unit slows down after the generator
breaker is closed.
Step 1: Disconnect the load share line from the DGC-2020HD. Run the single machine with load, and
verify that it loads and unloads correctly, and runs at the correct speed. Repeat for each
machine.
Step 2: Re-attach load share lines to all DGC-2020HDs that are part of the load sharing system. Run
the Single machine with load, and verify that it loads and unloads correctly, and runs at the
correct speed. If the machine slows down when the generator breaker is closed, check the load
share line voltage. It should be equal, on a normalized basis, to the normalized kW produced by
the generator. As an example, if the generator is loaded to 50% capacity, the Load Share Line
voltage should be at the midpoint of the range. If it is not, something is driving the load share
line that should not be. The single unit should be the only device driving the load share lines.
Step 3: Disconnect the load share lines from each non-running machine and see if the speed of the
running machine is correct. If a particular DGC-2020HD on a non-running machine seems to
affect the performance of the running machine, that DGC-2020HD may be damaged such that
the Load Share Line contacts are sticking, causing the DGC-2020HD to drive the load share
line even though the generator breaker is open. Tap the relays to see if the problem clears up.
If so, a faulty DGC-2020HD relay is indicated. Replace the DGC-2020HD, or wire in external
contacts to remove the DGC-2020HD from the load share system when the generator breaker
is closed.
Step 4: If it appears that something is driving the load share line but it is not the DGC-2020HD on one
of the non-running units, search for an external device that is driving or loading down the load
share lines.
Step 5: Repeat the preceding 3 steps for each machine.
DGC-2020HD Front Panel Diagnostics Screens
There are several diagnostic screens in the DGC-2020HD that can be useful for debugging load sharing
issues and I/O module related issues. The following debug screens are available: Load Share Line, AEM,
and CEM.
Load Share Line
This screen is useful for debugging load share related issues, and kW and var control related issues. It
gives visibility into the parameters metered and controlled by theDGC-2020HD.
The Load Share Line diagnostics screen is located on the front panel at Metering > Diagnostics > Load
Share Line.
The following parameters are visible on the Load Share Line diagnostics screen:

LS Input: Voltage the DGC-2020HD sees on its load share line input. Terminals P6-70 (LS –) and
P6-69 (LS+). This measurement is useful for debugging load share issues. Normally, all
machines that have their generator breakers closed should measure the same voltage for LS
Input. If this voltage differs, check for wiring errors, or problems with any relay contacts in the load
share line wiring. Any relay contacts that are used to switch load share lines, governor analog
speed bias signals, or voltage regulator analog bias signals must use a relay intended for low
voltage, low current applications to preserve signal integrity. Signal relays, not power relays, must
be used for this application.