8915-755 Woodward speed control module

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Product basic information
Manufacturer: Woodward
Model: 8915-755
Belonging to the famous 505 series
Supports multiple communication protocols and can be smoothly integrated with the existing control system of the factory
Core application: Designed specifically for speed control and protection of steam turbines
8915-755 controller has stable performance and high reliability

Categories: WOODWARD
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8915-755 Woodward speed control module

The 8915-755 is a microprocessor-based digital governor controller produced by Woodward, belonging to its classic 505 series.
It is primarily designed for speed control and protection of steam turbines. Below is a detailed introduction to this product:

I. Product Overview

Brand and Model: Woodward 8915-755
Series: 505 Series Digital Governor
Type: Microprocessor-based controller
Purpose: Specifically designed for steam turbines to control their speed and provide overspeed protection.

II. Core Functions

Speed Control:
- 8915-755 Precisely controls the speed of steam turbines by adjusting steam inlet flow.
- Supports single-range or split-range actuators to accommodate turbines of different sizes.
Overspeed Protection:
- Incorporates triple independent overspeed protection logic to ensure rapid shutdown in case of overspeed, preventing equipment damage.
- Provides an overspeed test button for convenient on-site testing of protection functions.
Emergency Shutdown:
- Equipped with an emergency stop button for immediate shutdown in emergency situations.
System Protection:
- - Automatically switches control modes upon sensor failure to ensure uninterrupted system operation.
  - Offers local/remote control priority selection to adapt to different operational scenarios.

Control Implementation of PID Controller
1. Feedback logic of PID

The feedback logic terms of various frequency converters are different, and there are even cases where similar terms have opposite meanings. The system design should be based on the instruction

manual of the selected frequency converter. The so-called feedback logic refers to the control polarity of the output frequency of the frequency converter based on the feedback signal detected by the sensor of the controlled physical quantity. For example

, in the central air conditioning system, the return water temperature is used to control and regulate the output frequency of the frequency converter and the speed of the water pump motor. When heating in winter,

if the return water temperature is low and the feedback signal decreases, it indicates that the room temperature is low. It is required to increase the output frequency of the frequency converter and the motor speed,

and increase the flow rate of hot water; During summer cooling, if the return water temperature is too low and the feedback signal decreases, it indicates that the room temperature is too low. This can reduce the

output frequency of the frequency converter and motor speed, and decrease the flow of cold water. As can be seen from the above, when the temperature is also low, the feedback signal decreases, but the frequency

change direction of the frequency converter is required to be opposite. This is the reason for introducing feedback logic. The functional selection of several frequency converter feedback logics is shown in Table 1.

2. Enable PID function

To achieve closed-loop PID control function, the PID function should first be pre-set as valid. There are two specific methods: one is to preset the function parameter code of the frequency converter. For example,
in the Convo CVF-G2 series frequency converter, when the parameter H-48 is set to O, there is no PID function; When set to 1, it is a normal PID control; When set to 2, it is the constant pressure water supply PID.

The second is determined by the status of the external multifunctional terminals of the frequency converter. For example, in the Yaskawa CIMR-G 7A series frequency converter, as shown in Figure 1, select any one

of the multifunctional input terminals Sl-S10 and preset the function codes H1-01 to H1-10 (corresponding to terminals S1-S10) to 19. This terminal has the function of determining whether PI [) control is effective.

It is invalid when it is “ON” and effective when it is “OFF” with the common terminal SC. It should be noted that most frequency

converters have both of the above preset methods, but there are a few brands of frequency converters that only have one of them.

In some systems with less strict control requirements, sometimes only using PI control function without activating D function can meet the needs, and the system debugging process is relatively simple.

III. Technical Specifications

Power Supply: 18-32 VDC, supporting 24VDC input.
Display: Two-line x 24-character LED display for clear indication of operating status and parameters.
Enclosure: NEMA 4X or IEC 60529 IP56 rated for protection against harsh industrial environments.
Inputs/Outputs:
- Inputs: 6 programmable current inputs, 16 discrete contact inputs.
- Outputs: 2 actuator outputs, 8 relay outputs, 6 programmable current outputs.
Communication Interfaces: 8915-755 Supports RS-232, RS-422, and RS-485 hardware interfaces for easy integration with host computers or other devices.
Software: Equipped with OpView™ and 505View software for parameter configuration, monitoring, and fault diagnosis.
Operating Temperature: -20 to +60°C (some models support -4 to +140°F).
Storage Temperature: -40 to +85°C (some models support -40 to +185°F).
8915-755 Weight: Approximately 9.11 pounds (4.13 kilograms).

IV. Application Scenarios

Steam Turbine Control: 8915-755Suitable for steam turbines of various sizes, including industrial steam turbines, small grid turbo-generators, and turboexpanders.
Single Extraction and Admission Applications: Designed for operating steam turbines in single extraction and/or admission applications.
On-Site Programming: Allows on-site operators to program and adjust parameters through an integrated operator control panel, adapting to different operating conditions.

V. Product Advantages

High Reliability:
- Microprocessor-based design ensures precise control and stability.
- Triple independent overspeed protection logic provides multiple layers of safety.
Flexibility:
- Supports various actuator and sensor configurations to accommodate different turbine models.
- Offers a rich set of input/output interfaces for easy system expansion and integration.
Ease of Use:
- Two-line x 24-character LED display provides an intuitive operating interface.
- A 30-key multifunctional keyboard simplifies parameter configuration and operation.
Compatibility:
- Supports multiple communication protocols for easy integration with DCS, PLC, and other systems.
- Provides OpView™ and 505View software for remote monitoring and fault diagnosis.