Basler Electric DECS-400 - Manual (Page 50)

38 9369700990 Rev R
Typical field overcurrent timing curves are illustrated in Figure 6. Notice that field current levels below
103% cause an annunciation in the same amount of time as field current at the 103% level. Also, field
current levels greater than 250% of the setpoint cause an annunciation in the same amount of time as
field current at the 250% level. The field current must fall below the dropout ratio (95%) for the function to
begin timing to reset.
Figure 6. Field Overcurrent Timing Curves
The following equations are used to calculate the field overcurrent pickup and reset time delays. In each
equation, MOP stands for multiple of pickup.
MOP
Setting Dial Time
(s) Delay Time PU
× − + −
× −
=
816 . 191 864 . 490 165 . 17
908 . 95
1
36 . 0
− ×
×
=
MOP MOP
Setting Dial Time
(s) Delay Time Reset
Field Overvoltage
Field overvoltage is annunciated when the field voltage increases above the Field Overvoltage Pickup
Level setting for the duration of the Field Overvoltage Delay setting. The Pickup Level setting is
adjustable from 1 to 2,000 Vdc in 1 Vdc increments. The Delay setting is adjustable from 0.2 to 30
seconds in 0.1 second increments. Field overvoltage protection can be enabled and disabled without
altering the Pickup Level and Delay settings.
Generator Undervoltage
Generator undervoltage is annunciated when the generator terminal voltage decreases below the
Generator Undervoltage Pickup Level setting for the duration of the Generator Undervoltage Delay
setting. The Pickup Level setting is adjustable from 0 to 75,000 Vac in 1 Vac increments. The Delay
setting is adjustable from 0.5 to 60 seconds in 0.1 second increments. Generator undervoltage protection
can be enabled and disabled without altering the Pickup Level and Delay settings.
Generator Overvoltage
Generator overvoltage is annunciated when the generator voltage terminal voltage increases above the
Generator Overvoltage Pickup Level setting for the duration of the Generator Overvoltage Delay setting.
The Pickup Level setting is adjustable from 0 to 575,000 Vac in 1 Vac increments. The Delay setting is
adjustable from 0.1 to 60 seconds in 0.1 second increments.
Loss of Sensing Voltage
Loss of sensing voltage is annunciated when the generator voltage decreases below the appropriate Loss
of Sensing Voltage Level setting for the duration of the Loss of Sensing Voltage Delay setting. The
Functional Description DECS-400