WOODWARD 8918-116

الوصف

The WOODWARD 8918-116 is a highly specialized and critical component within a turbine control system. It’s not a standalone actuator, but rather a CPC-DX – Dual Redundant Skid, Zone 2, 0-25 bar model.

WOODWARD 8918-116: CPC-DX Dual Redundant Skid (0-25 bar, Zone 2)

The WOODWARD 8918-116 is a complete, pre-assembled skid system designed for dual redundant operation of current-to-pressure conversion in demanding industrial environments, particularly within steam turbine control applications. It provides a robust and highly reliable interface between electronic control systems and hydraulic actuators that operate turbine valves.

Product Overview

This part number signifies a packaged solution that integrates two Woodward CPC-II units onto a single manifold, configured for fault-tolerant operation.

• Product Type: Dual Redundant Skid System for Current-to-Pressure Conversion
• Manufacturer: Woodward
• Part Number: 8918-116
• Model Designation: CPC-DX (Dual Transfer Skid)
• Components: Typically includes two CPC-II Current-to-Pressure Converters mounted on a common manifold with a transfer valve.
• Function:
  • Accepts a 4–20 mA pressure demand signal (and potentially redundant signals) from an electronic control system (e.g., a turbine controller or DCS).
  • Precisely regulates hydraulic oil pressure to control single-acting steam turbine governor valves.
  • Provides redundant operation, meaning if one CPC-II unit fails, the other can seamlessly take over control, ensuring continuous operation of the turbine.
• Output Pressure Range: 0 to 25 bar (0 to 363 psi).
• Hazardous Area Rating: Certified for Zone 2 hazardous locations, indicating it meets specific safety standards for environments where flammable gases, vapors, or mists may occasionally be present.

Detailed Product Description

The Woodward 8918-116 CPC-DX Dual Redundant Skid is engineered for maximum reliability and uptime in critical power generation and industrial processes. Its key features and benefits include:

• Dual Redundancy (Master/Slave Configuration): The skid houses two CPC-II units. In a typical setup, one unit operates as the master, controlling the output pressure, while the second unit acts as a hot-standby slave. The slave continuously tracks the master’s operation and is ready to bumplessly (without interruption) take over control of the output pressure should a failure occur in the master unit. This significantly enhances system availability and fault tolerance.
• Precision Pressure Control: Each CPC-II unit within the skid features a highly accurate internal pressure sensor and a PID (Proportional-Integral-Derivative) controller. This ensures precise and stable control over the hydraulic output pressure, which directly translates to accurate positioning of the turbine valve.
• “Dirt Buster” Technology: The integrated CPC-II units incorporate Woodward’s patented “Dirt Buster” or “Silt Buster” technology. This robust design, featuring a strong actuator, corrosion-resistant materials, a unique single-moving rotary valve, and a self-cleaning port design, makes the unit highly resistant to contaminated oil (up to ISO20/16 cleanliness). This is crucial for long-term reliability in industrial hydraulic systems.
• Enhanced Dynamics: The CPC-II units are designed for rapid and stable response to changes in control signals, which is vital for maintaining effective turbine speed and load control.
• Fail-Safe Mechanism: Each CPC-II unit has an internal valve-return-spring that forces it to a failsafe position (typically valve closure) in the event of an internal unit failure, loss of electrical input power, pressure sensor failure, or processor failure. The dual redundant setup further enhances this safety aspect.
• Diagnostic Features: The system provides comprehensive diagnostics, including status indications for pressure sensor health, input demand signal health, internal unit health, and input power quality. This allows operators to monitor the system’s operational status effectively.
• Simplified Installation and Maintenance: As a pre-engineered skid, it simplifies installation compared to integrating individual components. Repair kits (e.g., 8923-1996 for 10 bar, 8923-1997 for 25 bar) are available for the CPC replacement within the skid.

Technical Specifications (for the 8918-116 Skid)

Typical Applications

The WOODWARD 8918-116 CPC-DX Dual Redundant Skid is primarily used in critical heavy industrial applications where continuous and highly reliable operation of steam turbines is paramount:

• Steam Turbine Valve Control: Its core application is to accurately and redundantly position the control valves of single-acting steam turbines, which directly regulates steam flow, impacting turbine speed and power generation.
• Power Generation Plants: Integrated into the most critical control loops of large steam power plants, often in situations demanding the highest level of reliability and fault tolerance.
• Combined Heat and Power (CHP) Plants: Where continuous steam and power output are essential.
• Petroleum and Chemical Industries: Utilized in processes that rely on steam turbines for power or compression, where unexpected shutdowns can lead to significant losses.