Basler Electric DECS-250N - Manual (Page 64)

48 9440500990 Rev D
Protection DECS-250N
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
Field protection provided by the DECS-250N includes field overvoltage, field overcurrent, an exciter diode
monitor, and power input failure.
Field Overvoltage
A field overvoltage condition occurs when the field voltage exceeds the field overvoltage threshold A for the
duration of the field overvoltage time delay B . Field overvoltage protection can be enabled and disabled C
without altering the pickup and time delay settings. Field overvoltage pickup and trip elements in
BESTlogicPlus can be used in a logic scheme to initiate corrective action in response to the condition.
BESTlogicPlus field overvoltage settings are illustrated in Figure 36.
Figure 36. Field Overvoltage Protection Settings
A Field Overvoltage Pickup (V): Adjustable from 0 to 325 Vdc in 1 Vdc increments.
B Field Overvoltage Time Delay (s): Adjustable from 0.2 to 30 seconds in 0.1 second increments.
C Field Overvoltage Mode: Select Disabled or Enabled.
Field Overcurrent
A field overcurrent condition is annunciated when the field current exceeds the field overcurrent pickup
level
A for the duration of the field overcurrent time delay. Depending on the selected timing mode B , the
time delay can be fixed or related to an inverse function. Definite timing mode uses a fixed time delay C . In
inverse timing mode, the time delay is shortened in relation to the level of field current above the pickup
level. The time dial
D setting acts as a linear multiplier for the time to an annunciation. This enables the
DECS-250N to approximate the heating characteristic of the generator and generator step-up transformer