Woodward 505 User manual

Installation and Operation Manual
505 Digital Governor for Steam Turbines
with Single or Split-Range Actuators
Volume 2
Manual 85017V2C

WARNING
Read this entire manual and all other publications pertaining to the work to be
performed before installing, operating, or servicing this equipment. Practice all
plant and safety instructions and precautions. Failure to follow instructions can
cause personal injury and/or property damage.
The engine, turbine, or other type of prime mover should be equipped with an
overspeed shutdown device to protect against runaway or damage to the prime
mover with possible personal injury, loss of life, or property damage.
The overspeed shutdown device must be totally independent of the prime mover
control system. An overtemperature or overpressure shutdown device may also be
needed for safety, as appropriate.
CAUTION
To prevent damage to a control system that uses an alternator or battery-charging
device, make sure the charging device is turned off before disconnecting the
battery from the system.
Electronic controls contain static-sensitive parts. Observe the following
precautions to prevent damage to these parts.
• Discharge body static before handling the control (with power to the control
turned off, contact a grounded surface and maintain contact while handling the
control).
• Avoid all plastic, vinyl, and Styrofoam (except antistatic versions) around
printed circuit boards.
• Do not touch the components or conductors on a printed circuit board with
your hands or with conductive devices.
IMPORTANT DEFINITIONS
WARNING—indicates a potentially hazardous situation which, if not avoided, could
result in death or serious injury.
CAUTION—indicates a potentially hazardous situation which, if not avoided, could
result in damage to equipment.
NOTE—provides other helpful information that does not fall under the warning or
caution categories.
Revisions—Text changes are indicated by a black line alongside the text.
Woodward Governor Company reserves the right to update any portion of this publication at any time. Information
provided by Woodward Governor Company is believed to be correct and reliable. However, no responsibility is
assumed by Woodward Governor Company unless otherwise expressly undertaken.
© Woodward 1997
All Rights Reserved

Manual 85017V2 505 Digital Governor
Woodward i
Contents
ELECTROSTATIC DISCHARGE AWARENESS ..................................................III
INTRODUCTION............................................................................................1
CHAPTER 1. PERIPHERAL DEVICES..............................................................2
Overview.................................................................................................................2
505 HMI Software...................................................................................................2
CHAPTER 2. APPLICATION NOTES .............................................................12
Overview...............................................................................................................12
Example Applications...........................................................................................13
CHAPTER 3. OPERATOR INTERFACE ..........................................................39
Introduction...........................................................................................................39
Keypad and Display..............................................................................................39
Service Panel Modes............................................................................................40
Using the Service Mode .......................................................................................40
CHAPTER 4. SERVICE MODE PROCEDURES................................................60
Overview...............................................................................................................60
The 505 Service Mode .........................................................................................61
Service Mode Blocks............................................................................................70
Service Mode Worksheet Parameters .................................................................72
CHAPTER 5. UNDERSTANDING PID SETTINGS............................................92
Overview...............................................................................................................92
Proportional Response.........................................................................................93
Proportional + Integral (closed loop)....................................................................95
Derivative Response ............................................................................................96
Proportional + Derivative (closed loop)................................................................97
Proportional + Integral + Derivative (closed loop)................................................99
Controller Field Tuning General.........................................................................100
CHAPTER 6. HARDWARE/OPERATING SYSTEM FAULTS ............................103
General...............................................................................................................103
General...............................................................................................................103
APPENDIX A. 505 DESIGN SPECIFICATIONS.............................................107
Hardware Specifications.....................................................................................107
Software Specifications......................................................................................110
APPENDIX B. 505 SERVICE MODE WORKSHEET.......................................111
APPENDIX C. PASSWORD INFORMATION ..................................................114
General...............................................................................................................114
Service Mode Password.....................................................................................114
Debug Mode Password......................................................................................114
Configure Mode Password.................................................................................115
OS_FAULTS Mode Password............................................................................115
Download Configuration Function Password.....................................................115

505 Digital Governor Manual 85017V2
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Illustrations and Tables
Figure 1-1. 505 HMI Software ................................................................................3
Figure 1-2. Digital Remote Final Driver..................................................................4
Figure 1-3. Real Power Sensor..............................................................................5
Figure 1-4a. Digital Synchronizer and Load Control..............................................7
Figure 1-4b. Digital Synchronizer and Load Control Functional Diagram..............8
Figure 1-5. DSLC Interface Wiring.........................................................................9
Figure 1-6a. Master Synchronizer and Load Control...........................................10
Figure 1-6b. Master Synchronizer and Load Control Functional Diagram...........11
Figure 2-1. Pump or Compressor Discharge Pressure Control with Turbine Inlet
Pressure Limiting.............................................................................15
Figure 2-2. Inlet Pressure Control with Automatic Synchronizing & Generator
Power Limiting.................................................................................18
Figure 2-3. Exhaust Pressure Control with Generator Power Limiting and Plant
Import/Export Limiting......................................................................22
Figure 2-4. Plant Import/Export Control with DRFD Servo Interface ...................27
Figure 2-5. Inlet Pressure Control with Isochronous Loadsharing Control in Island
Mode................................................................................................31
Figure 2-6. Import/Export Control or Exhaust Pressure Control with Isoch Load
Sharing in Island Mode....................................................................34
Figure 3-1. 505 Keypad and Display....................................................................39
Figure 3-2. Software Structure Overview.............................................................41
Figure 3-3. The Select Mode Level......................................................................42
Figure 3-4. Header Level......................................................................................42
Figure 3-5. Block Level.........................................................................................43
Figure 3-6. Debug Information Arrangement .......................................................49
Figure 3-7. OS_FAULTS Mode Information Arrangement...................................50
Figure 3-8. SYS_INFO Mode Information Arrangement......................................55
Figure 4-1. Service Mode Entry............................................................................60
Figure 4-2a. Service Mode Blocks .......................................................................61
Figure 4-2b. Service Mode Blocks .......................................................................62
Figure 4-2c. Service Mode Blocks........................................................................63
Figure 4-2d. Service Mode Blocks .......................................................................64
Figure 4-2e. Service Mode Blocks .......................................................................65
Figure 4-2f. Service Mode Blocks ........................................................................66
Figure 4-2g. Service Mode Blocks .......................................................................67
Figure 4-2h. Service Mode Blocks .......................................................................68
Figure 4-2i. Service Mode Blocks.........................................................................69
Figure 5-1. Proportional Gain Setting Effects.......................................................93
Figure 5-2. Open Loop Proportional and Integral Response...............................94
Figure 5-3. Closed Loop Proportional and Integral Response.............................95
Figure 5-4. Integral Gain (Reset) Setting Responses..........................................96
Figure 5-5. Closed Loop Proportional and Derivative Action...............................98
Figure 5-6. Derivative Setting Effects...................................................................98
Figure 5-7. Closed Loop Proportional, Integral and Derivative Action.................99
Figure 5-8. Typical Response to Load Change................................................. 101
Table 2-1. Example Summary..............................................................................14

Manual 85017V2 505 Digital Governor
Woodward iii
Electrostatic Discharge Awareness
All electronic equipment is static-sensitive, some components more than others.
To protect these components from static damage, you must take special
precautions to minimize or eliminate electrostatic discharges.
Follow these precautions when working with or near the control.
1. Before doing maintenance on the electronic control, discharge the static
electricity on your body to ground by touching and holding a grounded metal
object (pipes, cabinets, equipment, etc.).
2. Avoid the build-up of static electricity on your body by not wearing clothing
made of synthetic materials. Wear cotton or cotton-blend materials as much
as possible because these do not store static electric charges as much as
synthetics.
3. Keep plastic, vinyl, and Styrofoam materials (such as plastic or Styrofoam
cups, cup holders, cigarette packages, cellophane wrappers, vinyl books or
folders, plastic bottles, and plastic ash trays) away from the control, the
modules, and the work area as much as possible.
4. Do not remove the printed circuit board (PCB) from the control cabinet
unless absolutely necessary. If you must remove the PCB from the control
cabinet, follow these precautions:
•Do not touch any part of the PCB except the edges.
•Do not touch the electrical conductors, the connectors, or the
components with conductive devices or with your hands.
•When replacing a PCB, keep the new PCB in the plastic antistatic
protective bag it comes in until you are ready to install it. Immediately
after removing the old PCB from the control cabinet, place it in the
antistatic protective bag.
CAUTION
To prevent damage to electronic components caused by improper handling,
read and observe the precautions in Woodward manual 82715, Guide for
Handling and Protection of Electronic Controls, Printed Circuit Boards, and
Modules.

505 Digital Governor Manual 85017V2
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Manual 85017V2 505 Digital Governor
Woodward 1
Introduction
Manual 85017 Volume 2 is a dual purpose manual. It includes application-
specific notes and 505 specific Service mode information.
The first part of this volume gives users an idea of the 505 Digital Control’s
capabilities, and how to apply them to a system. Typical applications are
schematically shown and their functionality explained. Programming and
Start/Run mode notes are given for each application to assist application
programmers in configuring the 505 for their application.
The second part of this volume includes 505 program modes not covered in
Volume 1 of this manual (Service, Debug, SYS_INFO, OPSYS Faults), PID
dynamic setting specifics, and Hardware rating information.
General Installation and Operating Notes and Warnings
This equipment is suitable for use in Class I, Division 2 , Groups A, B, C, and D
(Class I, Zone 2, Group IIC) or non-hazardous locations.
This equipment is suitable for use in European Zone 2, Group II environments
per compliance with EN60079-15, Electrical apparatus for explosive
atmospheres – Type of protection ‘n’
These listings are limited only to those units bearing the certification
identification.
Field wiring must be rated at least 75 °C for operating ambient temperatures
expected to exceed 50 °C.
Peripheral equipment must be suitable for the location in which it is used.
Wiring must be in accordance with North American Class I, Division 2 or
European Zone 2 wiring methods as applicable, and in accordance with the
authority having jurisdiction.
WARNING
Explosion hazard–Do not connect or disconnect while circuit is live unless
area is known to be non-hazardous.
Explosion Hazard–Substitution of components may impair suitability for
Class I, Division 2.
AVERTISSEMENT
Risque d’explosion–Ne pas raccorder ni débrancher tant que l’installation
est sous tension, sauf en cas l’ambiance est décidément non dangereuse.
Risque d’explosion–La substitution de composants peut rendre ce matériel
inacceptable pour les emplacements de Classe I, Division 2.

505 Digital Governor Manual 85017V2
2 Woodward
Chapter 1.
Peripheral Devices
Overview
This chapter provides a brief explanation of peripheral devices, that can be used
with the 505. By understanding the functionality of a peripheral device, a better
understanding of the overall control configuration can be achieved.
All the devices covered in this section are manufactured or supported by the
Woodward Governor Company. Peripheral devices manufactured by other
companies can be used with the 505 to perform the functions detailed bellow,
however, the compatibility of them to the 505 and the application should be
verified before system operation.
505 HMI Software
Woodward offers two different HMI software packages, OpView™ and 505View,
which allow an operator to remotely view operating inputs, adjust control
setpoints, issue Run mode commands, and monitor/troubleshoot the turbine
control. Both HMI packages are self-configuring which eliminates all field
engineering–they automatically configure their screens to match the control's
programmed application.
The OpView is comprised of an industrialized NEMA 4 touchscreen hardware
package bundles together with a Woodward developed software interface
program. The 505View is a unbundled Intellution-based software package that
runs on a pc (hardware can be optionally purchased). Both HMI packages are
pre–configured to communicate via Modbus®* protocol with either a 505 or 505E
Woodward steam turbine control and offer the following features:
*—Modbus is a trademark of Modicon, Inc.
• Automatic Screen Generation based on control configuration
• Security with multiple User Levels
• Remote Access Capability1
• Real-Time and Historical Trending2
• Alarm/Trip Status Indication
• Alarm/Trip Log with Time Tagging and First-Out Indication
• I/O and System Troubleshooting
• Graphic System Control screens
• Event Status Logging and History3
Notes:
1 505View only
2 OpView has Real-Time Trending only; 505View has both
3 OpView has Logging only; 505View has Logging and History
By connecting the OpView or 505View to either 505 Modbus port, it automatically
configures its screens to match the 505’s programmed application. If the 505 is
not configured to accept Modbus commands, the HMI functions as a system
monitor only. If the 505 is configured to accept Modbus commands, all 505 Run
Mode operations can be monitored and performed through it (start, stop, mode
enable/disable, setpoint raise/lower). For safety purposes, the Overspeed test
function can not be performed through the HMI. See Volume 1, Chapter 7 of this
manual for more information on programming Modbus ports.

Manual 85017V2 505 Digital Governor
Woodward 3
Figure 1-1. 505 HMI Software
User-friendly touch screens allow operators to view and control multiple modes
of operation and setpoints from one screen. Ten different screens are available
to allow operators the flexibility of viewing. These screens display the following
information:
• Controlling parameter information
• Complete starting sequences
• Turbine and/or Generator information
• Speed, Extr/Adm, Aux, Casc, & Limiter information
• Analog Input and Output levels
• Contact Input and Relay Output states
• Alarm and Shutdown Log
The OpView or 505View can interface with the 505 through serial RS-232, RS-
422, or RS-485 communications. By using RS-422 or RS-485 communications,
the HMI can be located up to 1220 m (4000 ft) from the 505 digital control.
Digital Remote Final Driver
A Digital Remote Final Driver (DRFD) is used to interface the 505 digital control
to existing valve operators or Woodward actuators that are integrating in action
or are not compatible with the 505.

505 Digital Governor Manual 85017V2
4 Woodward
The 505’s actuator outputs have the capability of driving a 4–20 mA or 20–160
mA (200 mA max) proportional signal into an actuator coil. These 505 actuator
output signals represent a demand signal equal to desired valve position
(proportional). If the application’s actuator or servo assembly requires a different
drive signal, or control action (integrating with a null setting), a Digital Remote
Final Driver or equivalent device must be used.
Figure 1-2. Digital Remote Final Driver
Woodward Digital Remote Final Drivers accept a 4–20 mA actuator-drive signal
proportional to desired valve position, and position a servo assembly accordingly.
Integrating or proportional type DRFDs are available depending on the servo
assembly being interfaced to. Woodward DRFDs have the capability of driving
unipolar or bipolar actuator demand signals, up to 0–400 mA or +400 mA
respectively.
The Digital Remote Final Driver is housed in a NEMA-4X enclosure with a hinged
cover and consists of driver and power supply modules. The driver module uses
plug-in jumpers and an alphanumeric display to facilitate field configuration and
calibration.
Proportional type DRFDs can provide an output drive signal of up to 400 mA, to
be compatible with existing servo assemblies. This drive signal is proportional to
the 4–20 mA input signal received from the 505 digital control.
Integrating type DRFDs sense actual valve position (through, LVDTs, RVDTs,
MLDTs, or dc position feedback devices), compare this signal to the input
position demand signal from the 505, and output a drive signal to position a
servo assembly accordingly. See Figure 1-2.
Real Power Sensor
A Real Power Sensor is used to sense the real power being produced by a
generator, or flowing through a tie line. Woodward Real Power Sensors sense
three phase volts, three phase amps, compare each phase’s voltage to current
relationship, and develop a 4–20 mA output proportional to real power.

Manual 85017V2 505 Digital Governor
Woodward 5
Figure 1-3. Real Power Sensor
Woodward manufactures two types of Real Power Sensors. The first type of RPS
is designed to sense power flow in one direction only (0 to +5 A CT current only),
and output a proportional 4–20 mA signal. This type of RPS was designed for
and should be used to sense generator power output. Many different real power
sensors of this type exist. Some of the optional RPS features include VAR
sensing, Loadsharing, 0–1 A CT current sensing, and multiple combinations of
these. Please consult a Woodward certified distributor or a Woodward factory for
the recommended RPS for your application.
The second type of RPS manufactured by Woodward is designed to sense
power flow through a bus-to-bus tie line. This RPS (8272-726) senses –5 A to +5
A CT current to allow its output to represent power flow in both directions. This
RPS provides a 4–20 mA power indication output signal where 12 mA represents
0 power flow. It is recommended that this RPS be used to sense power flow
through a tie line only. This RPS or equivalent is required to sense plant Import
and Export power.
Woodward Real Power Sensors have terminals labeled “Output” and terminals
labeled “KW Readout”. The “KW Readout” terminals provide a 4–20 mA signal
proportional to real power which is used by and compatible with the 505 control.
Thus the RPS terminals labeled “Output” are designed and typically compatible
only to Woodward’s 2301 type of control.
Woodward manufactured Real Power Sensors have a 2.5 Hz Low pass filter
(400 ms lag time) on their output to filter out the high frequency noise typically
created in a switch gear type environment. Thus if another vender’s watt
transducer is used, verification that it has similar filtering criteria should be
performed before it is applied with the 505. For more information on Woodward
Real Power Sensors, please refer to Woodward manual 82018.

505 Digital Governor Manual 85017V2
6 Woodward
Digital Synchronizer and Load Control (DSLC™)
The Woodward DSLC™ control is a microprocessor based generator load
control designed for use on three-phase ac generators with Woodward speed
controls and automatic voltage regulators. The DSLC is a synchronizer, a load
control, a dead bus closing system, a VAR/PF control, and a process control,
integrated into one package.
The 505 can be programmed to use the DSLC as a synchronizer only, or as a
synchronizer and load control. The DSLC provides either phase match or slip
frequency synchronizing, and ties into the unit automatic voltage regulator to
match voltages before paralleling. It interfaces with the 505 via a Speed bias
signal to control generator frequency and phase. When configured to use the
DSLC as a synchronizer only, the 505 must be programmed to receive the DSLC
Speed Bias signal through an analog input and have this input enabled through a
contact input or function key.
The DSLC communicates over a LAN using a digital Echelon network with other
system DSLCs to enable it to perform safe deadbus closings. Because the DSLC
performs all synchronizing functions simultaneously, synchronization typically
takes only a few seconds.
When used as a synchronizer and load control, the DSLC performs automatic
synchronization, and controls unit load based on the DSLCs mode of operation.
The DSLC can be in a base-load, loadsharing, remote load setting, or Process
control mode, depending on configuration and system conditions.
The DSLC’s baseload mode of operation allows an operator to set the unit to a
specified load. A proportional or integrating control action can be used with this
mode of operation. The integrating mode of operation can be used with systems
tying to an unstable grid to allow the unit to control at a constant load and not
vary based on grid frequency.
The DSLC’s loadsharing mode is used to share load with any other units using a
DSLC and tied to the same isolated bus. This mode is used in conjunction with a
Master Synchronizer & Load Control when paralleled to a utility to allow the
MSLC to control plant frequency or load depending on its state of operation.
The DSLC’s remote load setting mode allows load to be set by a remote 4–20
mA signal. The DSLC’s Process control mode allows any process directly related
to generator load to be controlled.
When using the DSLC as both a synchronizer and load control, the 505 control
must be programmed to receive the DSLC Speed Bias signal through an analog
input and have this input enabled through a contact input or function key.
After synchronization, unit load can be controlled by the DSLC (through the 505
Sync/Ld input) or by the 505’s internal speed/load setpoint. When the Sync/Ld
Share input is programmed, the position of the Utility Tie Breaker Contact selects
unit load control through the DSLC or through the 505’s internal load setpoint.
The DSLC interfaces to the 505 via a Speed Bias signal. From the many different
types of DSLCs manufactured by Woodward only a few have a Speed Bias
output (1–5 Vdc) compatible with the 505 control. The 505’s isolated analog #6
input is the only analog input that is directly compatible with the DSLC. Thus the
DSLC’s speed bias output should only be connected to the # 6 analog input. The
DSLC’s speed bias output is designed to drive into the 505’s low impedance
input.

Manual 85017V2 505 Digital Governor
Woodward 7
Once the generator is synchronized the DSLC soft-loads the unit to the load
setting determined by the mode of operation (base load, loadsharing, Process
control). When commanded the DSLC can also soft-unload the unit and issue a
breaker-open command at a set power level.
Figure 1-4a. Digital Synchronizer and Load Control

505 Digital Governor Manual 85017V2
8 Woodward
Figure 1-4b. Digital Synchronizer and Load Control Functional Diagram
Installation Notes
A Hand-held Programmer (9905-292) is required and used by the DSLC to
configure and calibrate it to the site specific application.
The DSLC requires a power source of +24Vdc @ 1 A. The 505 power supplies
can not supply this much power, thus an external power supply may be required.
The DSLC can interface with the unit Automatic Voltage Regulator through
contacts or a +9 volt bias signal.
For more information on Woodward’s Digital Synchronizer & Load Control,
please refer to Woodward manual 02007.

Manual 85017V2 505 Digital Governor
Woodward 9
Figure 1-5. DSLC Interface Wiring
Master Synchronizer and Load Control (MSLC)
The Woodward MSLC is a microprocessor based plant load control designed for
use in three-phase electric power generation sites equipped with Woodward
DSLCs which operate in parallel with the utility. The MSLC is a tie-line
synchronizer, a plant import/export load control, reactive load control (power
factor), and a master process control integrated into one package.
Used as a synchronizer, the MSLC provides phase (or slip frequency) and
voltage match synchronizing of the local plant bus to a main power grid. It
communicates over a LAN using a digital Echelon network with system DSLCs to
control plant frequency, phase, and voltage to perform automatic plant
synchronization.
After the utility tie breaker is closed manually or by the MSLC, the MSLC then
controls plant load to a baseload setting, remote load setting, import/export
demand setting, or process control demand setting. If programmed, reactive tie
line power can also be controlled by the MSLC through each DSLC interfacing to
each unit’s automatic voltage regulator.

505 Digital Governor Manual 85017V2
10 Woodward
The MSLC’s baseload mode of operation allows an operator to set the plant to a
specified load. A proportional or integrating control action can be used with this
mode of operation. The integrating mode of operation can be used with systems
tying to an unstable grid to allow the plant to control at a constant load and not
vary based on grid frequency.
Figure 1-6a. Master Synchronizer and Load Control

Manual 85017V2 505 Digital Governor
Woodward 11
Figure 1-6b. Master Synchronizer and Load Control Functional Diagram
The MSLC’s remote load setting mode allows plant load to be set by a remote
4–20 mA signal.
The MSLC’s import/export control mode, when enabled senses plant-to-utility tie
line power flow and controls this flow based on a import/export setpoint.
The MSLC’s process control mode allows any process directly related to plant
load to be controlled.
Once the plant-to-utility tie breaker is closed the MSLC soft-loads the plant to a
load setting determined by the mode of operation (base load, import/export,
Process control). When commanded the MSLC can also soft-unload the plant
and issue a plant-to-utility tie breaker open command at a set power level.
When using the MSLC as both a synchronizer and load control, the system
DSLCs must be in their Loadsharing mode to enable the MSLC to control them.
The MSLC is only active when synchronizing a plant bus to a utility bus, or when
the utility tie breaker is closed to control tie line power (real & reactive). Once the
utility tie breaker opens, the MSLC becomes disabled and does not effect DSLC
load sharing control. Because the MSLC/DSLC network only allows one master
controller at a time, only one MSLC at a time can be utilized to control plant load.
For more information on Woodward’s Master Synchronizer & Load Control and
how to apply it, please refer to Woodward manual 02022.
Installation Notes
A Hand-held Programmer (9905-292) is required and used by the MSLC to
configure and calibrate it to the site specific application.
The MSLC requires a power source of +24 Vdc @ 1 A. The 505 power supplies
can not supply this much power, thus an external power supply may be required.

505 Digital Governor Manual 85017V2
12 Woodward
Chapter 2.
Application Notes
Overview
This chapter is provided to give users an idea of the 505 Digital Control’s
capabilities, and how to apply them to a system. Typical applications are
schematically shown and their functionality explained. Programming and Start/
Run mode notes are given for each application to assist application programmers
in configuring the 505 for their application. Basic peripheral device connections
are shown in each application drawing to allow an understanding of how these
devices interface to the 505 and expand system capabilities.
Speed/Load PID
The Speed PID can control and limit:
• Unit Speed/Frequency
• Unit Load
The 505’s Speed PID can be used to control unit speed/frequency when isolated
and unit load when paralleled to an infinite bus (utility). The Speed PID can be
programmed to sense unit load via its actuator output signal or a 4–20 mA
analog input signal from a generator power sensor. When programmed to sense
and control generator load via a analog input true unit load is sensed and
controlled. By using the generator load signal to control from, any turbine inlet or
exhaust pressure variation is sensed and compensated for, thus providing true
load control.
A combination of the Speed PID and its setpoint limits allow this PID to limit unit
load. When used as a unit load limiter, it is recommended that the 505 be
configured to sense and control only true generator load. If applying the 505
system to a soft grid (utility frequency varies greatly) it is recommended that unit
load limiting be performed by the Auxiliary PID not the Speed PID.
Auxiliary PID
The 505’s Auxiliary PID can be programmed to control or limit:
• Turbine Inlet Steam Pressure
• Turbine Inlet Steam Flow
• Turbine Exhaust Steam pressure
• Turbine Exhaust Steam Flow
• Generator Power output
• Plant or Tie line Import/Export Power
• Process Temperature
• Compressor Suction pressure
• Compressor Suction Flow
• Compressor Discharge pressure
• Compressor Discharge Flow
• Any process parameter related to unit load, inlet pressure/flow, or exhaust
pressure/flow (depending on configuration)

Manual 85017V2 505 Digital Governor
Woodward 13
The 505’s Auxiliary PID can be used as a limiter or controller (enabled/disabled
on command). When programmed as a limiter this PID’s output is Low Signal
Selected with the Speed PID’s output. This configuration allows the Auxiliary PID
to limit the unit’s load based on the parameter being sensed.
When the Auxiliary PID is configured as a controller, it must be enabled and
disabled by commands given through the 505’s front panel, contact input, or
Modbus communications. With this configuration when the Aux PID is enabled
the Speed PID is disabled and tracks the Auxiliary PID’s output.
To control or limit any of the listed parameters, the 505 must be programmed to
accept an Auxiliary analog input signal representing that parameter’s level. The
exception to this rule is when controlling or limiting generator load, the Auxiliary
PID can be programmed to use and share the KW/Unit load input with the Speed
PID.
Cascade PID
The 505’s Cascade PID can be programmed to control:
• Turbine Inlet Steam Pressure
• Turbine Inlet Steam Flow
• Turbine Exhaust Steam pressure
• Turbine Exhaust Steam Flow
• Generator Power output
• Plant or Tie line Import/Export Power
• Process Temperature
• Compressor Suction pressure
• Compressor Suction Flow
• Compressor Discharge pressure
• Compressor Discharge Flow
• Any process parameter related to unit load, inlet pressure, or exhaust
pressure (depending on the configuration)
The 505’s Cascade PID can be used to control any of the listed parameters. This
PID must be enabled and disabled by commands given through the 505’s front
panel, contact input, or Modbus communications.
The Cascade PID is cascaded with the Speed PID to vary unit speed/load. By
directly positioning the Speed PID’s setpoint, the Cascade PID can vary unit
speed/load to control its input parameter. This configuration allows for bumpless
transfers between the two control modes (Speed/Load and Cascade).
Example Applications
The example applications in this chapter do not show every possible control
configuration or combination. However, these examples can also be used as a
reference to apply any of the controlling combinations or parameters not listed or
shown. To apply a desired control parameter or combination not shown, refer to
one or more of the typical application configurations that are shown and
resemble the control configuration desired, then substitute the shown control
parameters with the required control parameters.
To apply a desired control parameter or combination not shown, refer to one or
more of the typical application configurations that are shown and resemble the
control configuration desired, then substitute the shown control parameters with
the required control parameters.

505 Digital Governor Manual 85017V2
14 Woodward
Example–To configure the 505 to perform a Turbine Exhaust pressure limiting
function use Example 1, the “Pump or Compressor Discharge Pressure Control
with Turbine Inlet Pressure Limiting” application for reference. With this example
substitute exhaust pressure for inlet pressure and disregard any program
settings specified to control pump or compressor discharge pressure.
The examples shown in this chapter are summarized as follows:
• Example 1: Pump or Compressor Discharge Pressure Control with Inlet
Pressure Limiting
• Example 2: Inlet Pressure Control with Auto Synchronizing and Generator
Power Limiting
• Example 3: Exhaust Pressure Control with Plant Import/Export Power
Limiting
• Example 4: Plant Import/Export Power Control with DRFD Servo Interface
• Example 5: Inlet Pressure Control with Isochronous Load Share Control in
Island Mode
• Example 6: Plant Import/Export Power Control with Isochronous Load Share
Control in Island Mode
• Example 7: Induction Generator Control
The features and functionality shown in each example are summarized in table
2–1.
Table 2-1. Example Summary