WOODWARD 505E Digital Governor for Extraction Steam Turbines
Description
General：The 505E is a 32-bit microprocessor-based control designed to control single extraction, extraction/admission, or admission steam turbines. The 505E is field programmable which allows a single design to be used in many different control applications and reduces both cost and delivery time. It uses menu driven software to instruct site engineers on programming the control to a specific generator or mechanical drive application. The 505E can be configured to operate as a stand-alone unit or in conjunction with a plant’s Distributed Control System.
Operator Control Panel：The 505E is a field configurable steam turbine control and operator control panel (OCP) integrated into one package. A comprehensive operator control panel, including a two- line (24 characters each) display, and a set of 30 keys is located on the 505E’s front panel. This OCP is used to configure the 505E, make OnLine program adjustments, and operate the turbine/system. Easy to follow instructions are presented in English through the OCP’s two-line display and operators can view actual and setpoint values from the same screen.
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.
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.
Control Overview:The 505E Digital Governor is designed to control extraction, extraction/ admission, or admission steam turbines. The difference between these turbines is the capability of the turbine to allow low pressure steam, which is at a lower pressure than the inlet, to enter and/or exit the turbine. An extraction turbine allows the lower pressure (extraction) steam to exit the turbine only and will have a non-return valve in the extraction header/line to prevent steam from entering the turbine. An admission turbine (also called induction) will allow excess header steam to enter the turbine through the low pressure inlet. An extraction/admission turbine will allow low pressure header steam to enter or exit the turbine depending on system pressures. A turbine with admission capability will have a stop valve or trip-and-throttle valve in the low pressure line to prevent steam from entering the turbine when the unit is tripped. The type of turbine used will depend on the system requirements and must be designed by the turbine manufacturer to perform the functions required.
The 505E has two independent control channels available, the speed/load and auxiliary controllers. The outputs of these two controllers are low-signal-selected (LSS) to provide to speed/load demand signal to the ratio/limiter. In addition to these channels, the speed/ load controller can be manipulated by another controller, the cascade controller. The cascade controller is ‘cascaded’ into the speed controller, whereby the speed controller setpoint is changed directly by the cascade controller output. The auxiliary controller can act as either a control channel or as a limiting channel. All three of these PID controllers have the option of utilizing an analog input signal to remotely position their setpoints. Additional features of the 505E include frequency control, isochronous loadsharing, critical speed avoidance, idle/rated control, and an automatic start sequence. There are two serial communications ports which can be used to monitor and control the turbine using Modbus protocol.
Extraction Turbines:The 505E control can be configured to operate single automatic extraction turbines by controlling the interaction of the governor (HP or high pressure) valve and the extraction (LP or low pressure) valve. (The 505E can also operate the governor valve and the first extraction valve of multiple extraction turbines).
Single automatic extraction turbines have a high pressure stage and a low pressure stage, each controlled by a valve. Steam enters the turbine through the HP valve (see Figure 1-2). At the downstream end of the HP turbine stage and before the LP valve, steam can be extracted. The LP valve controls the entry of steam into the LP turbine stage, and the diverting of steam through the extraction line. As the LP valve is opened, more steam enters the LP stage and less is extracted.
In most cases, the operator of an extraction turbine needs to maintain both turbine speed/ load and extraction pressure/flow at constant levels. Changing the position of either the HP valve or the LP valve affects both turbine speed/load and extraction. If either the load on the turbine or the extraction demand changes, both the HP valve position and the LP valve position must be changed to maintain speed/load and extraction. The movement of both valves is automatically calculated by the 505E’s ratioing logic based on the turbine performance parameters to minimize valve/process interaction.
Admission Turbines:The 505E control can be configured to operate single automatic admission turbines by controlling the interaction of the governor (HP or high pressure) valve and the extraction (LP or low pressure) valve.
Single automatic admission turbines have a high pressure stage and a low pressure stage, each controlled by a valve. Steam enters the turbine through the HP valve (see Figure 1-3) and at the downstream end of the HP turbine stage, before the LP valve. The LP valve controls the entry of steam into the LP turbine stage and through the admission line. As the LP valve is opened, more steam enters the LP stage.
In most cases, the operator of an admission turbine needs to maintain both turbine speed/ load and admission pressure/flow at constant levels. Changing the position of either the HP valve or the LP valve affects both turbine speed/load and admission. If either the load on the turbine or the admission demand changes, both the HP valve position and the LP valve position must be changed to maintain speed/load and admission.
The movement of both valves is automatically calculated by the 505E’s ratioing logic based on the turbine performance parameters to minimize valve/process interaction.
Extraction and Admission Turbines:The 505E control can be configured to operate single automatic extraction and admission turbines by controlling the interaction of the governor (HP or high pressure) valve and the extraction (LP or low pressure) valve.
Single automatic extraction and admission turbines have a high pressure stage and a low pressure stage, each controlled by a valve. Steam enters the turbine through the HP valve (see Figure 1-2). At the downstream end of the HP turbine stage and before the LP valve, steam can either be extracted or admitted (inducted) into the LP turbine stage. The LP valve controls the entry of steam into the LP turbine stage. As the LP valve is opened, more steam enters the LP stage and less is extracted.
In most cases, the operator of an extraction turbine needs to maintain both turbine speed/ load and extraction or admission pressure/flow at constant levels. Changing the position of either the HP valve or the LP valve affects both turbine speed/load and extraction or admission. If either the load on the turbine or the extraction / admission demand changes, both the HP valve position and the LP valve position must be changed to maintain speed/ load and extraction/ admission. The movement of both valves is automatically calculated by the 505E’s ratioing logic based on the turbine performance parameters to minimize valve/process interaction.
Stock part list:
9907-162
9907-018
9907-014
9907-164
8200-224
8200-226
9907-028
9907-147
9907-165
9907-167
9907-205
8440-1546
8440-1706
8440-1809
8444-1092
8516-039
9905-860
9905-969
9905-970
9905-971
9906-707
9905-204
9905-760
8200-1301
8200-1302
8440-1934
9907-163
A8516-039
8290-195
8525-971
Post time: Mar-11-2026