505E Digital Governor
Manual 85018V1
4
Woodward
Turbine Control Parameters
The 505E interfaces with two control valves (HP & LP) to control two parameters
and limit an additional parameter, if desired. These two controlled parameters are
typically speed (or load) and extraction/admission pressure (or flow), however,
the 505E could be utilized to control or limit: turbine inlet pressure or flow,
exhaust (back) pressure or flow, first stage pressure, generator power output,
plant import and/or export levels, compressor inlet or discharge pressure or flow,
unit/plant frequency, process temperature, or any other turbine related process
parameter. Refer to Volume 2 for details on applications.
Communications
The 505E can communicate directly with plant Distributed Control Systems
and/or CRT based operator control panels, through two Modbus
®
*
communication ports. These ports support RS-232, RS-422, or RS-485
communications using ASCII or RTU MODBUS transmission protocols.
Communications between the 505E and a plant DCS can also be performed
through hardwired connections. Since all 505E PID setpoints can be controlled
through analog input signals, interface resolution and control is not sacrificed.
*—Modbus is a trademark of Schneider Automation Inc.
Additional Features
The 505E also provides the following features: First-Out Trip Indication (5 total
trip inputs), Critical Speed Avoidance (2 speed bands), Auto Start Sequence (hot
& cold starts), Dual Speed/Load Dynamics, Zero Speed Detection, Peak Speed
Indication for Overspeed trip, and Isochronous Loadsharing between units.
Using the 505E
The 505E control has two normal operating modes, the Program Mode and the
Run Mode. The Program Mode is used to select the options needed to configure
the control to your specific turbine application. Once the control has been
configured, the Program Mode is typically never again used, unless turbine
options or operation changes. Once configured, the Run Mode is used to operate
the turbine from start-up through shutdown. In Addition to the Program and Run
modes, there is a Service Mode which can be used to enhance system operation
while the unit is running. Refer to Volume 2 for information on the Service Mode.
505E Inputs and Outputs
Control Inputs
Two speed inputs which are jumper configurable for MPU (magnetic pickup units)
inputs or proximity probes.
Six analog inputs are available. One is dedicated as the extraction/admission
input. The remaining five are configurable. The sixth analog input has isolation
circuitry and should be used for a self-powered signal that is not isolated.
