Advantage of eddy current displacement sensor in steam turbine

Steam turbines, as crucial power equipment in modern industry, play a vital role in various fields such as power generation, petroleum, and chemical engineering. The stable operation of their rotating machinery is of paramount importance to the safety and reliability of the entire production system. Radial vibration is a common issue during the operation of steam turbines. If not monitored and controlled accurately and promptly, it may lead to equipment failure or even accidents. Eddy current displacement sensors, with their unique performance advantages, have been widely applied in the online measurement and safety protection of radial vibration of steam turbine rotating machinery, providing a strong guarantee for the stable operation of the equipment.-

Special eddy current sensor for steam turbine

I. Working Principle of Eddy Current Displacement Sensors

Eddy current displacement sensors operate based on the principle of electromagnetic induction. When the sensor's probe approaches a conductive object (such as the shaft of a steam turbine), the high-frequency electromagnetic field generated by the probe coil induces eddy currents on the surface of the object. These eddy currents, in turn, produce a magnetic field opposite to the original field, affecting the inductance of the probe coil. By measuring the change in the inductance of the probe coil, the relative displacement between the object and the probe can be obtained.

II. Measurement of Radial Vibration of Steam Turbine Rotating Machinery

1. System Composition

The eddy current displacement sensor system typically consists of a probe, an extension cable, and a preamplifier. The probe is the part that directly contacts the object to be measured, and its size and shape are selected based on measurement requirements; the extension cable is used to connect the probe and the preamplifier, and its length can be determined according to on-site installation conditions; the preamplifier is responsible for amplifying, processing, and converting the signal detected by the probe, ultimately outputting a signal that can be monitored and analyzed.

2. Measurement Process

During the operation of a steam turbine, the probe of the eddy current displacement sensor is installed near the shaft, maintaining a certain gap from the shaft surface. When the shaft undergoes radial vibration, the distance between the shaft and the probe changes, and the sensor detects this change and converts it into an electrical signal. After processing by the preamplifier, real-time data on the radial vibration of the shaft can be obtained. These data can be transmitted to the monitoring system for real-time display, recording, and analysis of the shaft's vibration.

3. Measurement Advantages

(1) Non-contact measurement: Eddy current displacement sensors use a non-contact measurement method, which does not cause wear or interference to the object being measured, making them suitable for measuring the high-speed rotating shafts of steam turbines.

(2) High precision and resolution: They can accurately measure minute displacement changes, with a resolution of sub-micron level, effectively detecting the minute vibrations of steam turbine shafts.

(3) Fast dynamic response: They can track rapid vibration changes of the shaft in real time, providing accurate data for dynamic monitoring of the equipment.

(4) Strong anti-interference ability: In complex industrial environments, they have strong resistance to electromagnetic and vibration interference, ensuring the stability of the measurement signal.

III. Safety Protection of Radial Vibration of Steam Turbine Rotating Machinery Shaft

1. Fault Diagnosis and Early Warning

By conducting real-time analysis of the radial vibration data measured by the eddy current displacement sensor, abnormal vibration conditions of the steam turbine shaft can be detected in a timely manner. For instance, when the shaft experiences faults such as imbalance, misalignment, or friction, the vibration signal will undergo significant changes. The monitoring system can issue early warning signals based on preset alarm thresholds when the vibration amplitude exceeds the normal range, alerting operators to take appropriate measures to prevent further deterioration of the fault.

2. Protection Mechanism

In the safety protection system of the steam turbine, the measurement data from the eddy current displacement sensor can serve as an important input signal. When the radial vibration of the shaft exceeds the safety limit, the protection system can automatically trigger an emergency shutdown procedure, cutting off the power source of the steam turbine to prevent equipment damage due to excessive vibration and ensure the safety of the equipment and personnel.

3. Maintenance and Overhaul Guidance

The long-term accumulated radial vibration data can also provide a reference basis for the maintenance and overhaul of the steam turbine. Through trend analysis of the vibration data, potential equipment faults can be predicted in advance, allowing for the rational arrangement of overhaul plans, reducing equipment downtime and maintenance costs. Additionally, based on the characteristics of the vibration data, the specific location and cause of the fault can be determined, providing clear guidance for maintenance personnel and improving the efficiency and quality of maintenance.

Eddy current displacement sensors, with their advantages of non-contact measurement, high precision, high resolution, fast dynamic response and strong anti-interference ability, play an irreplaceable role in the online measurement and safety protection of the radial vibration of turbine rotating machinery shafts. By monitoring the radial vibration of the rotating shaft in real time, abnormal conditions of the equipment can be detected promptly, providing accurate data support for fault diagnosis, early warning and protection, and effectively ensuring the stable operation and production safety of the turbine. With the continuous development of sensor technology and the deepening of application, eddy current displacement sensors will be applied more widely in the industrial field, providing more reliable guarantees for the operation safety and reliability of various rotating machinery.