Basler Electric DGC-2020 - Manual (Page 172)

Figure 4-52. Overvoltage
A Pickup: Adjustable from 70 to 1,000 Vac in 1 Vac increments. (Note: The maximum voltage that can be
safely applied to the DGC-2020 is 576 Volts. The pickup range is higher so that when the low-line
override is used, and the scale factor is 0.5 or less, effective protection levels of 500 Volts can be
reached with 0.5 scale factor.)
B Activation Delay: Adjustable from 0 to 30 s in 0.1 s increments.
C Alarm Configuration: None, Alarm, Pre-Alarm, or Status Only.
D Hysteresis: Adjustable from 1 to 60 Vac in 1 Vac increments.
E Low Line Scale Factor: Adjustable from 0.001 to 3 in increments of 0.001.
F Pickup (Per Unit): Range varies based on the values of the native unit setting and the associated rated
data parameter.
Phase Imbalance (47)
DGC-2020 controllers with enhanced generator protection (style number xxxxxxExx) are capable of
protecting against voltage imbalances between any of the three phases. The pickup setting entered is
based on the VT secondary side (DGC-2020). A phase imbalance condition is annunciated when the
difference between any of the three phases of generator voltage increases above the 47 pickup setting
A
for the duration of the 47 activation delay setting B . A phase imbalance annunciation can be user-selected
to trigger a pre-alarm C (warning) or alarm C (shutdown). A phase imbalance annunciation can also be user-
configured to close a programmable output.
The hysteresis setting D functions as a phase imbalance dropout by preventing rapid switching of the
pickup output.
A low-line scale factor setting E is used to automatically adjust the phase imbalance pickup setting in
applications that might utilize more than one type of genset connection. The scale factor setting is
implemented when the DGC-2020 senses a contact closure at a contact input programmed to activate
scaling of the protection settings. The value of the scale factor setting serves as a multiplier for the pickup
setting. For example, if a scale factor contact input is received by the DGC-2020 and the scale factor
setting is 2.000, the pickup setting will be doubled (2.000
× PU).
The element is disabled when Alarm Configuration is set to “None”. Element status is available in
BESTlogicPlus Programmable Logic when “Status Only” is selected.
Settings which are related to machine ratings can be set in either actual units of voltage or in per unit F
values. When a native unit is edited, BESTCOMSPlus automatically recalculates the per unit value based
on the native unit setting and the rated data parameter (on the System Parameters, Rated Data screen)
associated with it. When a per unit value is edited, BESTCOMSPlus automatically recalculates the native
value based on the per unit setting and the rated data parameter associated with it.
Once all per unit values are assigned, if the rated data parameters are changed, BESTCOMSPlus
automatically recalculates all native unit settings based on the modified rated data parameters.
The following setting has native units of Secondary Volts, and the rated data associated with it is Rated
Secondary Volts (on the System Parameters, Rated Data screen).
•
Phase Imbalance 47 Pickup
The BESTCOMSPlus Phase Imbalance screen is illustrated in Figure 4-53.
4-62 DGC-2020 BESTCOMSPlus
® Software
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