Basler DECS-250, Instruction Manual

Page: 64 / 352

48 9440300990 Rev J
Protection DECS-250
Figure 34. Generator Capability Curve vs. 40Q Response
Pickup and Trip
A loss of excitation condition exists when the level of absorbed vars exceeds the loss of excitation (40Q)
threshold
A
for the duration of the 40Q time delay
B
. A time delay setting of zero makes the loss of excitation
element instantaneous with no intentional time delay. If the pickup condition subsides before the time
delay expires, the timer and pickup are reset, no corrective action is taken, and the element is rearmed for
any further occurrences of loss of excitation.
The 40Q threshold is expressed as a percentage of the rated var flow for the machine. Loss of excitation
protection can be enabled and disabled
C
without altering the pickup and time delay settings.
BESTCOMS Plus loss of excitation settings are illustrated in Figure 35.
Figure 35. Loss of Excitation Protection Settings
A
Pickup (% of rated vars): Adjustable from 0 to 150% in 1% increments.
B
Time Delay: Adjustable from 0 to 300 seconds in 0.1 second increments.
C
Mode: Select Disabled or Enabled.
Field Protection
BESTCOMSPlus Navigation Path: Settings Explorer, Protection, Field
HMI Navigation Path: Settings, Protection, Field