Basler Electric DGC-2020ES - Manual (Page 66)

58 9469200990 Rev C
Figure 23. Settings Explorer, Generator Protection, Voltage, Phase Imbalance (47) Screen
Frequency
Two sets of frequency protection settings are provided: one for underfrequency (81U) and one for
overfrequency (81O).
Underfrequency (81U)
An underfrequency condition is annunciated when the generator frequency decreases below the 81U
pickup setting for the duration of the 81U activation delay setting. An underfrequency annunciation can be
user-selected to trigger a pre-alarm (warning) or alarm (shutdown). An underfrequency annunciation can
also be user-configured to close a programmable output.
A voltage-based inhibit setting prevents an 81U trip from occurring during an underfrequency condition
associated with system startup.
The hysteresis setting functions as an underfrequency dropout by preventing rapid switching of the pickup
output.
Overfrequency (81O)
When the generator frequency increases above the 81O pickup setting for the duration of the 81O
activation delay setting, an overfrequency condition is annunciated. An overfrequency annunciation can
be user-selected to trigger a pre-alarm (warning) or alarm (shutdown). An overfrequency condition can
also be user configured to close a programmable output.
The hysteresis setting functions as an overfrequency dropout by preventing rapid switching of the pickup
output.
The element is disabled when Alarm Configuration is set to “None”. Element status is available in
BESTlogicPlus Programmable Logic when “Status Only” is selected.
Alternate Frequency Scale Factor
An alternate frequency scale factor setting is used for automatic adjustment of the frequency pickup
settings in applications that may utilize more than one operating frequency. For example, a machine that
is configurable between 50 or 60 Hz operation. The scale factor setting is implemented when the DGC-
2020ES senses a contact closure at a contact input that is connected to the Alternate Frequency Override
logic element in BESTlogicPlus Programmable Logic. When the Alternate Frequency Override is true, the
scale factor setting serves as a multiplier for the pickup settings. For example, if an alternate frequency
scale factor contact input is received by the DGC-2020ES and the scale factor setting is 2.000, the pickup
setting is doubled (2.000 x PU).
Generator Protection DGC-2020ES