Manual 37443A DSLC-2 - Digital Synchronizer and Load Control
Page 14/226 © Woodward
Process Control
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A cascade PID process controller is provided for cogeneration, import/export control, pond level maintenance,
pressure maintenance or other application. An adjustable bandwidth signal input filter, flexible PID controller ad-
justments and control selectable for direct or indirect action, allow the process control to be used in a wide variety
of applications.
The analog input “Process Signal Input” provides the real value for the DSLC-2 control. The control includes an
internal digital process reference which may be controlled by raise and lower load switch contact inputs or by the
analog input “Process Signal”.
Adjustable ramps allow smooth entry to or exit from the process control mode. When the process control mode is
selected, an adjustable ramp moves the load reference in a direction to reduce the process control error. When the
error is minimized or the reference first reaches either the specified high or low load pick-up limits, the process
controller is activated. When a limit is reached, the control will hold the load reference at that limit until process
control is obtained.
When unloading from the process control, an adjustable unload ramp provides time controlled unloading to the
unload trip level. When load reaches the unload trip level, the DSLC-2 control automatically issues a breaker
open command to remove the generator set from the system. The ramp pause switch input allows holding of the
unload ramp for cool-down or other purposes.
Additional functions include selectable and adjustable process high and low limit switches and alarm activation.
Var/PF Control
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The var/PF functions control the reactive power component of the generator in parallel systems. In an infinite bus
system, the controller compares either the kvar load or power factor (selectable) on the generator with an adjusta-
ble internal reference and makes corrections to the voltage regulator until the desired kvar load or power factor is
obtained. For higher performance, the “Voltage Bias” output, can be directly connected to compatible voltage
regulators with analog voltage setting input. The control has raise and lower voltage discrete inputs for manual
voltage adjustment. The control also has raise and lower contact outputs to activate a voltage regulator MOP
when an analog input is not provided on the AVR.
The var/PF controller will limit the generators kvar output to the generator rated reactive power setpoint when
connected to an infinite bus. A DSLC-2 must be in baseload or process control or a MSLC-2 must be in control.
This will protect the generator when connected to an infinite source. This feature is not active when the DSLC-2
is in the load sharing mode (isolated).
The DSLC-2 control provides var sharing between multiple units when in an isolated bus application. The control
computes an average var value for the system and uses it as the reference input to the var controller. The control
includes an adjustable voltage reference and voltage trim function in the sharing function to maintain system vol-
tage. The analog input “Reactive Load” is activated by closing both the voltage raise and lower discrete inputs.
This allows remote control of the PF reference setpoint when in power factor control. Each power factor setpoint
either external or internal is calculated to a var load setpoint. var load setpoints are restricted within the range -10
% to 100 % generator rated reactive power.
The DSLC-2 control has a selectable voltage range alarm which is activated if the analog output to the voltage
regulator reaches high or low saturation. The DSLC-2 control also has selectable and adjustable high and low
voltage limit switches and alarm outputs.
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