Basler DECS-250, Instruction Manual

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9440300990 Rev J 65
DECS-250 Limiters
Automatic adjustment (scaling) of the overexcitation limiter and stator current limiter is possible through
the DECS-250 auxiliary control input. Limiter scaling settings are illustrated in Figure 53. OEL and SCL
scaling may be independently enabled and disabled
A
. Automatic adjustment of the OEL and SCL is based
on six parameters: signal and scale for three points (levels).
With the scaling input set to Auxiliary Input , the signal value
B
for each point represents the auxiliary
control input. This input can be a 4 to 20 mAdc signal applied to terminals I+ and I– or a –10 to +10 Vdc
signal applied to terminals V+ and V–. (The input type is selected in BESTCOMS
Plus ). See the Auxiliary
Control chapter of this manual for details.
With the scaling input set to AEM RTD # , the signal value for each point represents an AEM RTD input in
degrees Fahrenheit. See the Analog Expansion Module chapter of the manual for details.
The scale value
C
for each point defines the limiter low level as a percent of rated field current for the OEL
and rated stator current for the SCL.
Figure 53. Limiter Scaling Settings
A
OEL and SCL Scale Enable: Select Auxiliary Input, AEM RTD 1 to AEM RTD 8, or Disabled.
B
Signal: Adjustable from –10 to +10 in 0.01 increments when Auxiliary Input is selected.
Adjustable from –58 to +482 in increments of 1 when any AEM RTD input is selected.
C
Scale: Adjustable from 0 to 200 in increments of 0.1.
Underfrequency Limiter
BESTCOMSPlus Navigation Path: Settings Explorer, Operating Settings, Limiters, Underfrequency
HMI Navigation Path: Settings, Operating Settings, Limiters, UEL
The underfrequency limiter is selectable for underfrequency limiting or volts per hertz limiting
A
. These
limiters protect the generator from damage due to excessive magnetic flux resulting from low frequency
and/or overvoltage.
Underfrequency and volts per hertz limiter settings are illustrated in Figure 56.
If the generator frequency decreases below the corner frequency
B
for the selected underfrequency slope
C
(Figure 54), the DECS-250 adjusts the voltage setpoint so that the generator voltage follows the
underfrequency slope. The adjustment range of the corner frequency and slope settings enables the
DECS-250 to precisely match the operating characteristics of the prime mover and the loads being
applied to the generator.