Winco DGC-2020 - Manual (Page 118)

H Overfrequency Alarm Configuration: None, Alarm, Pre-Alarm, or Status Only.
I Hysteresis: Adjustable from 0.1 to 40 Hz in 0.1 Hz increments.
Reverse Power Protection (32)
Two sets of reverse power settings are provided: one for three-phase generator connections and one for
single-phase generator connections. The pickup setting entered is based on the CT secondary side
(DGC-2020). When a single-phase override contact input is received by the DGC-2020, the reverse
power protection settings automatically switch from the three-phase settings to the single-phase reverse
power protection settings. The 32 element monitors three-phase real power when three-phase sensing is
active or single-phase real power if single-phase sensing is active.
When the total wattage in the tripping direction (generator absorbing power) is greater than the pickup
setting
A for the duration of the 32 activation delay setting B , a reverse power condition is annunciated. A
reverse power annunciation can be user-selected to trigger a pre-alarm C (warning) or alarm C (shutdown).
A reverse power annunciation can also be user-configured to close a programmable output.
The hysteresis setting
D functions as a reverse power 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
BESTlogic+ Programmable Logic when “Status Only” is selected.
BESTCOMSPlus reverse power protection settings (DGC-2020, Generator Protection, Reverse Power)
are illustrated in Figure 4-45.
Figure 4-45. Reverse Power Protection Settings
A Pickup: –50% to +5% of rated watts in 0.1% increments.
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 10% in 0.1% increments.
Loss of Excitation Protection (40Q)
Two sets of loss of excitation settings are provided: one for three-phase generator connections and one
for single-phase generator connections. The pickup setting
A entered is based on the CT secondary side
(DGC-2020). When a single-phase override contact input is received by the DGC-2020, the loss of
excitation protection settings automatically switch from the three-phase settings to the single-phase loss
of excitation protection settings.
When a generator’s excitation power is lost, the generator acts as a large inductor. The generator begins
to absorb large quantities of vars. The 40Q acts on the principal that if a generator begins to absorb vars
outside of its steady state capability curve, it has likely lost its normal excitation supply. The 40Q monitors
three-phase reactive power when three-phase sensing is active or single-phase reactive power if single-
phase sensing is active. It compares the reactive power to the 40Q response curve defined by the 40Q
pickup setting. Refer to Figure 4-46.
4-48 DGC-2020 BESTCOMSPlus Software 9400200990 Rev K