Woodward 9907-120 | Governor | Controller | Potential Converter
1.9907-120 Product Overview
The Woodward 9907-120 belongs to the 505/505E series digital turbine controllers. It is a microprocessor-based control module designed for single-valve steam turbines,
including single extraction/admission systems or split-range actuator configurations.
The controller features a front panel Operator Control Panel (OCP) with a two-line, 24-character display and multi-function keypad, allowing easy on-site configuration and monitoring.
2. 9907-120 Technical Specifications and Parameters
| Parameter | Details |
|---|---|
| Power Supply | +24 VDC, approx. 1 A |
| I/O Outputs | Discrete Outputs: 8 Analog Outputs: 6 Actuator Outputs: 2 |
| Display / HMI | Two-line, 24-character LCD, with multi-function keypad |
| Dimensions | Approx. 14 × 11 × 4 in (35.6 × 27.9 × 10.2 cm) |
| Weight | Approx. 9.11 lbs (4.13 kg) |
| Operating Temperature | –4 to +140 °F (–20 to +60 °C) |
| Storage Temperature | –40 to +185 °F (–40 to +85 °C) |
| Humidity Standard | 95% RH at 20-55 °C for 48 hours without damage |
| Protection Class | Typically meets industrial dust and water protection standards |
| Communication Protocol | Supports Modbus, RS-232 / RS-422 serial interfaces |
3. Brand History
Woodward, Inc., founded in 1870 and headquartered in Fort Collins, Colorado, USA, is a global leader in energy control systems. The company has a long history of innovation in turbine control, engine management,
and power generation systems.
Woodward products are widely recognized for their reliability and precision in demanding industrial and power generation applications.
4. Applications in Industrial Automation
The 9907-120 plays a critical role in industrial automation and power generation environments:
- Steam Turbine Control: Manages startup, speed regulation, and extraction/admission control of steam turbines.
- Power Generation Systems: Used in power plants to regulate turbine-driven generators for stable frequency and load management.
- Compressor and Pump Drive Control: Ensures precise speed control for turbine-driven compressors and pumps.
- Process Industry Applications: Applied in chemical plants, refineries, and other industries requiring precise turbine operation.
- Safety and Protection Functions: Includes overspeed protection, critical speed avoidance, actuator travel limits, and event logging for operational safety.
Servo drive control mode
1. Feedback compensation type open-loop control
The accuracy of open-loop systems is relatively low due to the step error, start stop error, and mechanical system error of servo drives,
which directly affect the positioning accuracy. Compensation type improvement should be adopted, which has the advantages of both open-loop and
closed-loop systems, namely open-loop stability and closed-loop accuracy. It will not cause system oscillation due to resonance frequency, crawling, or
loss of motion of the machine tool. Feedback compensation type open-loop control does not require gap compensation and pitch compensation.
2. Closed-loop control
Due to the inability of open-loop control to meet the requirements of machine tools, the most fundamental way to improve the control accuracy of servo
drives is to adopt closed-loop control. There is not only a predecessor control channel, but also a feedback channel for detecting output. After comparing the command signal
with the feedback signal, a deviation signal is obtained, forming a closed-loop control system with deviation control.
3. Semi closed loop control
For closed-loop control systems, reasonable design can achieve reliable stability and high accuracy, but directly measuring the position signal of the workbench requires
the use of position detection devices with high installation and maintenance requirements, such as gratings, magnetic rulers, or linear induction synchronizers.
By measuring the angular displacement of the transmission shaft or screw, the equivalent feedback signal of the position output can be indirectly obtained. Due to
the fact that the errors caused by this part of the transmission cannot be automatically compensated by the closed-loop system without including the transmission
chain from the rotating shaft to the worktable, the errors caused by this part of the transmission cannot be automatically compensated by the closed-loop system. Therefore,
this closed-loop control system composed of equivalent feedback signals is called a semi closed loop servo drive, and this control method is called a semi closed loop control method.
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