9469300994 9-19
DGC-2020HD Troubleshooting
set by the Ramp Rate (%) parameter in the AVR Bias Control settings. Note the rate is in terms of
percentage of machine capacity, it is not the time to ramp from zero up to the current desired var
level. Thus, at low var loading it may appear that the ramp is skipped. If the system is loaded to
only 10% and a unit is brought on line where the load rate is 10% per second, it takes only one
second to reach 10% of capacity.
• var Demand: This is the normalized requested kvar demand on the generator. It is normalized
such that 1.0 indicates the full kvar capacity of the generator, 0.5 indicates 50% of the generator’s
capacity, etc. When the generator breaker is closed, and the var/PF controller is enabled, the var
Demand indicates what level of reactive power should be generated. In an island load share
system, this will be determined by the droop characteristics set by the Droop Percentage and
Voltage Droop Gain parameters. If the generator breaker is closed, and the Parallel To Mains
logic element is true, the var Demand will be equal to the kvar set point if the var/PF controller is
in var mode or it will be calculated from the amount of kW being generated to maintain desired
machine Power Factor when the var/PF controller is in Power Factor control mode. When the
generator breaker is open, or the var/PF controller is disabled, the var Demand will be zero.
• Volt PID: This is the current output value of the Voltage PID controller. It will normally range
between –1.0 and 1.0, and will generally be zero at all times unless synchronization is in
progress.
• kvar PID: This is the current output value of the kvar PID controller. It will normally range between
–1.0 and 1.0, and will be zero any time the generator breaker is open. If the var/PF controller is
enabled, the kvar PID will be nonzero when the generator breaker is closed if there is any
difference between the normalized kvar generation and the var Demand value of the machine. If
the var/PF controller is disabled, the kvar PID will always be zero.
• Volt Error: This is the normalized difference between the measured generator voltage and the
voltage to which the DGC-2020HD is trying to synchronize. It will be 0.00 at all times except when
the DGC-2020HD is trying to synchronize its generator inputs to its bus input. When
synchronizing, this will typically be 0.000 or some relatively small number and move a small
amount above and below 0.000 as voltage controller corrects for any voltage errors.
• kvar Error: This is the normalized difference between the measured generator kvar generation
and the var Demand described above. A value of 1.0 means the difference is equal to the Rated
kvar of the machine; a value of –1.0 means the difference is equal to the negative of the Rated
kvar of the machine. When the generator breaker is open, or if var/PF controller is disabled, this
will always be 0.000. When var/PF control is enabled, and the generator breaker is closed, this
will typically be 0.000 or some relatively small number and move a small amount above and
below 0.000 as the var/PF controller corrects for var errors. If a reactive load is added or dropped
from the system, the error will be nonzero until the var/PF controller brings the var generation to
the desired level.
• Voltage Bias: This is the normalized value to which the voltage regulator analog bias output of the
DGC-2020HD will be driven to accomplish desired kvar and Voltage control. It is equal to the sum
of the Volt PID and the kvar PID. If the value is –1.0, the voltage bias output will be driven to the
minimum value of the voltage regulator analog bias output range. If the value is 1.0, the output
will be driven to the maximum value of the voltage regulator analog 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 voltage regulator analog bias output range. If the generator breaker is
open, or if the generator breaker is closed and kvar control is disabled, the Volt Bias value will be
0.00, driving the bias output to the midpoint of the voltage regulator analog bias output range
indicating the voltage regulator should operate the generator at rated voltage.
AEM-2020
This screen shows the binary data that is being sent between the AEM-2020 (Analog Expansion Module)
and the DGC-2020HD.
The AEM diagnostics screen is located on the front panel at Metering > Diagnostics > AEM.
The following parameters are visible on the AEM diagnostics screen:
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