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Troubleshooting DGC-2020HD
Step 5: If a particular machine is expected to start, but does not, check the sequencing status and
verify that the settings are properly configured. Group Start Requests for Start One or Start
Demand Based may not start all units because the unit in question may not have been within
the set of generators that should have started based on the sequencing criterion.
Generator Does Not Stop During a Group Stop Request
Step 1: Verify that a Group Stop Request is active. In the BESTCOMSPlus Metering Explorer, navigate
to DGC-2020HD > System Status > Breaker. Examine the Group Stop Req column for nonzero
entries. Nonzero entries indicate active group stop requests.
Step 2: Check that the generator to stop is in the same Generator Group in the Group Segment
Settings as the breaker generating the Group Stop Request. Only generators in the same
Generator Group as the Generator Group configured for the breaker issuing the Group Stop
Request will respond.
Step 3: Verify that the generators to be stopped are in Auto mode and Sequencing and Demand
Start/Stop are enabled.
Step 4: Verify that the generator to be stopped does not have an active Run with Load Start and is not
running due to an applied ATS contact. Either case will supersede Group Stop Requests and
prevent the generator from stopping.
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,
Control, AEM-2020, CEM-2020, VRM, Mains Power and VRM Control.
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 the DGC-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.
• Speed Bias: This is the normalized value to which the DGC-2020HD drives the governor analog
bias output. If the value is –1.0, the output will be driven to the minimum value of the governor
bias output range. If the value is 1.0, the output will be driven to the maximum value of the
governor bias output range. If the value is 0.000, the output will be driven to the midpoint value
(i.e. half way between maximum and minimum values) of the governor bias output range. If the
generator breaker is open, or if the generator breaker is closed and speed trim and kW control
are disabled, the output from the DGC-2020HD will be the midpoint of the range, indicating the
generator should run at rated speed. Any relay contacts that are used to switch load share lines,
governor analog speed bias signals, or voltage regulator analog voltage 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.
• Voltage Bias: This is the normalized value to which the DGC-2020HD drives the voltage regulator
analog bias output. If the value is –1.0, the output will be driven to the minimum value of the
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