Winco DGC-2020 - Manual (Page 75)

9400200990 Rev B DGC-2020 BESTCOMSPlus Software 4-25
(DGC-2020). When a single-phase override contact input is received, the DGC-2020 automatically
switches from the three-phase undervoltage settings to the single-phase undervoltage settings.
An undervoltage condition is annunciated when the average of the three-phase (three-phase mode) or
the line-to-line voltage (single-phase mode) decreases below the corresponding 27 pickup setting
A for the
duration of the corresponding 27 activation delay
B
. An undervoltage annunciation can be user-selected to
trigger a pre-alarm
C
(warning) or alarm
C
(shutdown). An undervoltage annunciation can also be user-
configured to close a programmable output.
A frequency-based inhibit setting
D
prevents a 27 trip from occurring during an undervoltage condition
associated with system startup.
A low-line scale factor setting E is used to automatically adjust the undervoltage pickup settings in
applications that may utilize more than one type of genset connections. 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
settings. 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).
Overvoltage (59)
Two sets of overvoltage settings are provided: one for three-phase generator connections and one for
single-phase generator connections. The pickup setting entered is based on the VT secondary side
(DGC-2020). When a single-phase override contact input is received, the DGC-2020 automatically
switches from the three-phase overvoltage settings to the single-phase overvoltage settings.
An overvoltage condition is annunciated when the average of the three-phase (three-phase mode) or the
line-to-line voltage (single-phase mode) increases above the corresponding 59 pickup setting
F for the
duration of the corresponding 59 activation delay G . An overvoltage annunciation can be user-selected to
trigger a pre-alarm
H
(warning) or alarm
H
(shutdown). An overvoltage annunciation can also be user-
configured to close a programmable output.
A low-line scale factor setting I is used to automatically adjust the overvoltage pickup settings in
applications that may utilize more than one type of genset connections. 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
settings. 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).
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
J
for the duration of the 47 activation delay setting
K
. A phase imbalance annunciation can be user-selected
to trigger a pre-alarm
L
(warning) or alarm
L
(shutdown). A phase imbalance annunciation can also be user-
configured to close a programmable output.