Woodward MSLC Master Synchronizer and Load Control Process Control

Process Control

A process controller is provided for cogeneration, fluid level maintenance,

pressure control, or other applications. An adjustable bandwidth signal input filter,

flexible PID controller adjustments, an adjustable deadband, and control

selectable for direct or indirect action, allow the process control to be used in a

wide variety of applications.

A 4–20 mA (1–5 Vdc or a 4–12–20 mA) process transmitter provides the process

signal to the MSLC. The MSLC includes an internal digital process reference

which may be controlled by the raise and lower switch contact inputs or by an

external 4–20 mA (1–5 Vdc) remote process reference. The output of the

process control, like the import/export control, is the percentage of rated load

setpoint to the individual generators in isochronous load sharing.

An adjustable ramp allows smooth entry and exit from the process control mode.

When the process control mode is selected, the load reference is ramped in a

direction to reduce the error between the process input and the process

reference. When the error is minimized or the reference first reaches either the

high or low specified pull-in limits, the process controller is activated. When the

load reference output reaches either 100% or 0%, the control will maintain that

load reference until process control is established. The MSLC is not capable of

overloading or reverse powering in order to attempt to meet the process

reference. The high and low limit switches mentioned above can be used to

indicate that either too many or too few generators are on-line to maintain the

process within its limits.