Basler Electric DGC-2020 - Manual (Page 179)

BESTCOMSPlus is used to set the 51-x Programmable Curve Constants. To program the Curve
Constants, open the Generator Protection/Current tree branch and select the overcurrent element to be
modified. Select P from the Curve pull-down menu and then enter the calculated values for each
constant.
Programmable curve coefficients can only be entered when the P curve is chosen for the protection
element from the Curve drop-down menu.
Figure 4-58. Overcurrent
A Pickup: Adjustable from 1 to 20 Aac for 5 Aac current sensing (style number 5xxxxxxxx) or 0 to 4 Aac
for 1 Aac current sensing (style number 1xxxxxxxx).
B Alarm Configuration: None, Alarm, Pre-Alarm, or Status Only.
C Time Dial: Adjustable from 0 to 7,200 s for F (fixed) curve, 0 to 9.9 for all other curve selections.
D Curve: A, B, C, D, E1, E2, F, G, I1, I2, L1, L2, M, P, S1, S2, V1, or V2.
E Overcurrent Pickup Curve.
F Low Line Scale Factor: Adjustable from 0.001 to 3 in 0.001 increments.
G Display: Single Phase or 3 Phase.
H Reset Type: Instantaneous or Integrating.
I Pickup (Per Unit): Range varies based on the values of the native unit setting and the associated rated
data parameter.
J Programmable Curve (P) Coefficients: Refer to Table 4-7.
Loss of Mains Protection
Loss of mains protection consists of one vector shift element and one rate of change of frequency
element (style number xxxxxxExx only). The functionality of these elements is similar in that they are both
intended to disconnect the generator from the grid when a loss of mains or mains failure occurs,
preventing the generator from remaining tied to the mains if the mains returns due to an external reclose
device. When the mains is lost, it is likely that the generator load will shift abruptly since the generator is
driving everything between the generator output and the utility breaker that removed mains power. Such a
load shift is likely to cause a speed shift, which might result in the generator being out of phase with the
mains when a reclose occurs. If the generator is out of phase and connection with the mains is
established, damage could occur.
Loss of mains protection is only active when the generator is paralleled to the mains as indicated when
the Parallel To Mains logic element is true in BESTlogicPlus. The protection is inhibited for five seconds
after Parallel To Mains first becomes true so that transients from closing onto the mains will not cause
false trips.
To minimize false trips, loss of mains protection is disabled if any breakers are not closed.
9400200990 Rev X DGC-2020 BESTCOMSPlus
® Software
4-69