Basler Electric DECS-250N - Manual (Page 49)

9440500990 Rev D 33
DECS-250N Auxiliary Control
Auxiliary Control
BESTCOMSPlus Navigation Path: Settings Explorer, Operating Settings, Auxiliary Inputs
HMI Navigation Path: Settings, Operating Settings, Auxiliary Inputs
The DECS-250N accepts an external analog control signal for auxiliary control of the regulation setpoint.
Auxiliary setpoint control is possible in all regulation modes: AVR, PF, Var, FCR, and FVR. The control
signal can also be used for limiter scaling or power system stabilizer control. Auxiliary control settings are
illustrated in Figure 22.
Auxiliary Control Input Type A
Either a voltage or current control signal may be used for auxiliary control. Terminals I+ and I– accept a 4
to 20 mAdc signal. Terminals V+ and V– accept a –10 to +10 Vdc signal. An adjacent terminal labeled
GND provides the connection for a recommended cable shield. The input type is selected in
BESTCOMSPlus
® .
Auxiliary Control Input Function B
The analog control input can be used for auxiliary control of the regulation setpoint, as a power system
stabilizer test input, or for limiter scaling.
PSS Test Input
The auxiliary control input can be used for control of the optional power system stabilizer function during
testing and validation. More information is provided in the Power System Stabilizer chapter of this manual.
Limiter Scaling
When the auxiliary control input is configured for limiter scaling, the stator current limiter (SCL) and
overexcitation limiter (OEL) low-level values can be automatically adjusted. Automatic adjustment of the
SCL and OEL is based on six parameters: signal and scale for three points. The signal value for each
point represents the accessory input voltage. The scale value defines the limiter low level as a percentage
of rated field current for the OEL and rated stator current for the SCL. For accessory input voltages
between two of the three defined points, the low-level limiter setting is linearly adjusted between the two
scale values. Limiter settings and limiter scaling are discussed in detail in the Limiters chapter of this
manual.
Setpoint Limits
Minimum and maximum setpoint limits are observed when the With Limit box is checked.
Auxiliary Control Gains
When a current input type is selected, the input current is converted internally by the DECS-250N into a
voltage signal in the range of –10 to +10 Vdc. The DECS-250N uses the following equation when
converting the applied current into a voltage.
𝑉
𝑎𝑢𝑥
= (𝐼
𝑎𝑢𝑥
− 0.004) × �
20.0
0.016� − 10.0
Equation 6. Input Current to Voltage Signal Conversion
Where: V
aux
is the calculated voltage signal and I
aux
is the applied current in amperes.
For setpoint control, V
aux
is multiplied by the appropriate regulation mode auxiliary gain setting.
If the auxiliary input is unused, all auxiliary control gains should be set to zero.