Woodward 8440-1955 | Governor | Controller | Potential Converter
1.8440-1955 Product Overview
The Woodward 8440-1955 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. 8440-1955 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 8440-1955 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.
The function of stepper motor driver
A stepper motor driver is an actuator that can convert the electrical pulse signal it receives into angular displacement.
When the stepper motor driver receives an electrical pulse signal, it drives its stepper motor to rotate a fixed angular
displacement (we call it the “step angle”) according to the originally set direction. Its rotation is carried out step by step at a fixed angle.
We can control the displacement of its angle by controlling the number of pulses it sends, in order to achieve precise positioning; At the same time,
we can also control the speed and acceleration of the stepper motor by controlling the frequency of its pulse signal, thereby achieving its speed regulation and positioning goals.
Widely used in various carving machines, crystal grinding machines, medium-sized CNC machine tools, EEG embroidery machines, packaging machinery, fountains,
dispensing machines, cutting and feeding systems,
and other large and medium-sized CNC equipment with high resolution requirements.
The number of phases of a stepper motor refers to the number of coil groups inside the stepper motor. Commonly used stepper motors include two-phase, three-phase,
four phase, and five phase. The step angle of a regular two-phase stepper motor varies depending on the number of phases, with a step angle of 1.8 degrees
for a three-phase motor, 1.2 degrees for a three-phase motor, and 0.72 degrees for a five phase motor. When there is no stepper motor subdivision driver configured,
users mainly rely on selecting stepper motors with
different numbers of phases to meet the requirements of step angle. If a subdivision driver is used, the phase number will become meaningless, and users only need
to change the subdivision number on the driver to modify the step angle.
After the subdivision of stepper motor drivers, there will be a qualitative leap in the operational performance of the motor, but all of this is generated by the driver itself
and has nothing to do with the motor and control system. When in use, the only thing that users need to pay attention to is the change of the step angle of the stepper motor,
which will have an impact on the frequency of the step signal sent by the control system. As the step angle of the stepper motor will decrease after subdivision,
the frequency of the requested step signal should be correspondingly increased. Taking a 1.8 degree stepper motor as an example: the step angle of the
driver is 0.9 degrees in half step state, and 0.18 degrees in ten step state. Therefore, under the condition of requesting the same motor speed, the frequency of the step signal
sent by the control system is 5 times that of half step operation in ten step state.
The accuracy of a regular stepper motor is 3-5% of the step angle. The deviation of a single step in a stepper motor does not affect the accuracy of the next step,
so the accuracy of the stepper motor does not accumulate.
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