Basler Electric DGC-2020 - Manual (Page 364)

Step 2: Re-attach load share lines to all LSM-2020s 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 LSM-2020 on a non-running machine seems to affect
the performance of the running machine, that LSM-2020 may be damaged such that the Load
Share Line contacts are sticking, causing the LSM-2020 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 LSM-2020 relay is indicated. Replace the LSM-2020, or wire in external contacts to
remove the LSM-2020 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 LSM-2020 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-2020 Front Panel Debug Screens
There are several debug screens in the DGC-2020 that can be useful for debugging load sharing issues
and I/O module related issues. The following debug screens are available: LOAD SHARE DEBUG,
CONTROL DEBUG, CEM DEBUG, and AEM DEBUG.
LOAD SHARE DEBUG
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 LSM-2020.
The LOAD SHARE DEBUG screen is located on the front panel at SETTINGS > SYSTEM PARAMS >
REMOTE MODULE SETUP > LSM SETUP > LOAD SHARE DEBUG.
The following parameters are visible on the LOAD SHARE DEBUG screen:
•
FDBK VOLT: Voltage the LSM-2020 sees on its load share line input. Terminals P2-5 (LS–) and
P2-6 (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 FDBK VOLT. 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.
•
AUX VOLT: Voltage the LSM-2020 sees on its analog input. Terminals P2-8 (IN–) and P2-9 (V+).
•
AUX CURRENT: Current the LSM-2020 sees on its analog input. Terminals P2-7 (IN+) and
P2-8 (IN–).
•
SPEED BIAS: This is the normalized value to which the LSM-2020 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 LSM-2020 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.
•
VOLT BIAS: This is the normalized value to which the LSM-2020 drives the voltage regulator
analog bias output. If the value is –0.1, the output will be driven to the minimum value of the
voltage regulator bias output range. If the value is 1.0, the output will be driven to the maximum
value of the voltage regulator bias output range. If the value is 0.00, the output will be driven to
the midpoint value (i.e. half way between maximum and minimum values) of the voltage regulator
8-10 DGC-2020 Maintenance and Troubleshooting 9400200990 Rev X