Solenoid valve CNAC-02323 is a key actuator in the steam turbine safety protection system. It is designed for large thermal power generating units, especially for the fire-resistant oil system (EH oil system) of 660MW units. As the core component of the automatic shutdown trip (AST) series, the solenoid valve ensures the rapid response of the steam turbine under abnormal conditions through precise opening and closing control, ensuring the safe shutdown of the unit and avoiding equipment damage and accident expansion.

Solenoid valve CNAC-02323 adopts a direct-acting electromagnetic drive structure, which consists of core components such as cast steel valve body, armature assembly, reset spring and electromagnetic coil. Under normal working conditions, the solenoid valve remains in a normally closed state, and the valve core seals the valve port through the spring preload force to block the flow of the medium. When the control system detects dangerous signals such as overspeed, excessive vibration or abnormal oil pressure, the solenoid valve coil is instantly energized, generating a strong electromagnetic field to drive the armature to move, overcome the spring resistance and quickly open the valve port, cut off the steam inlet channel of the turbine main steam valve or regulating valve, and achieve millisecond-level rapid shutdown. After power failure, the spring force pushes the valve core to reset and the system returns to standby state.

Core performance parameters

- Drive mode: 110V DC power drive to ensure high response speed and anti-interference ability;

- Pressure resistance level: Design pressure ≥31.5MPa, which can adapt to the high-pressure working conditions of fire-resistant fuel system;

- Temperature adaptability: The working temperature range is -20℃~150℃, the valve body is made of high-temperature cast steel, and the surface is hardened;

- Sealing performance: The valve core and valve seat are made of hard alloy surfacing, the sealing surface roughness is ≤0.4μm, and the leakage level reaches ANSI VI level;

- Protection level: IP65 protection standard, effectively resisting the erosion of harsh environments such as oil mist and dust.

Technical advantages

1. Fast response: full stroke action time ≤50ms, meeting the timeliness requirements of emergency shutdown of steam turbine;

2. High pressure adaptability: optimized flow channel design reduces pressure loss, and can still operate stably under 31.5MPa conditions;

3. Long life design: the armature guide structure adopts self-lubricating composite materials, and the cycle life exceeds 100,000 times;

4. Intelligent diagnosis: built-in coil temperature sensor, real-time monitoring of the working status of the solenoid valve and upload to the DCS system.

The Solenoid valve CNAC-02323 is mainly integrated in the steam turbine AST oil circuit system, linked with the emergency trip module, and executes overspeed protection (OPC) and emergency shutdown (ETS) instructions. In 660MW units, it is usually configured in groups (such as 2/3 voting logic) to improve reliability. Daily maintenance needs to focus on:

- Electrical inspection: Regularly measure the coil resistance (standard value 42Ω±5%) and insulation resistance (≥100MΩ);

- Sealing test: Perform valve seat sealing test every 5000 hours, and the pressure drop rate must be ≤0.2MPa/min;

- Clean management: The cleanliness of fire-resistant oil must be maintained at NAS level 5 to prevent particulate matter from causing valve core jamming;

- Preventive replacement: It is recommended to replace the entire valve every 6 years or after 50,000 operations to avoid fatigue failure.

The solenoid valve CNAC-02323, through precise structural design and strict process control, continues to provide reliable protection for the generator set under extreme conditions of high temperature, high pressure and high frequency operation, and is an indispensable core component in the intelligent safety system of modern power plants.

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