In thermal power plants, the opening control of turbine valves is directly related to the efficiency and safety of the unit. As the core technical equipment in this field, the LVDT displacement sensor 0508.902T0201.AW020 has become the “smart eye” for high-precision valve monitoring with its unique electromagnetic induction principle and precise structural design.

I. Core technology: electromagnetic induction principle and differential signal processing

The core of LVDT is to achieve non-contact measurement through the physical characteristics of core displacement and electromagnetic field coupling. Taking the 0508.902T0201.AW020 model as an example, its primary coil generates an alternating magnetic field after receiving an AC excitation signal of 5-10kHz. The secondary coil adopts a symmetrical reverse winding structure. When the core moves with the valve stem, the magnetic flux of the secondary coils on both sides differs, forming a differential voltage signal.

Key innovations:

1. High-sensitivity differential design: The secondary coil adopts reverse series connection, so that the output voltage difference is strictly linear with the core displacement, and the sensitivity can reach 0.1μm.

2. Phase demodulation technology: The built-in phase-sensitive rectifier circuit can convert AC signals into DC voltage, and at the same time determine the displacement direction through phase changes, eliminating the limitation of unidirectional measurement of traditional sensors.

3. Adaptive temperature compensation: The nickel-based alloy shell and temperature compensation algorithm are used to make the linear error of the sensor less than ±0.5%FS in the range of -40℃~200℃.

III. Precision structure: modular design and anti-interference optimization

The mechanical structure of the displacement sensor 0508.902T0201.AW020 has been specially optimized to meet the stringent requirements of high temperature and high vibration environment of steam turbines:

1. Triple protection system:

• Coil skeleton: Alumina ceramic material is used, with a temperature resistance of more than 300℃ to avoid magnetic circuit deviation caused by thermal expansion.

• Electromagnetic shielding layer: Multi-layer Permalloy coating suppresses strong electromagnetic interference during the start-up and shutdown of steam turbines, and the signal-to-noise ratio is increased to 90dB.

• Shockproof bracket: Titanium alloy universal joint connector and buffer spring design can withstand 20g vibration acceleration to prevent the core from breaking due to mechanical impact.

2. Redundant monitoring mechanism:

To deal with the risk of single-point failure, the displacement sensor 0508.902T0201.AW020 is equipped with dual independent output channels and realizes signal cross-checking through the DCS system. When the deviation of a signal exceeds the set threshold, the system automatically switches to the backup channel to ensure continuous monitoring capability.

III. Accuracy guarantee: full optimization from signal acquisition to closed-loop control

1. Signal conditioning technology:

The microvolt AC signal output by the sensor needs to be processed at multiple levels:

• Preamplification: The low-noise instrument amplifier increases the signal gain to 1000 times while suppressing common-mode interference.

• Digital filtering: The adaptive filter based on the FIR algorithm eliminates 50Hz power frequency noise and high-frequency harmonics, with an effective bandwidth of 5kHz.

• Linear calibration: Full-scale calibration is performed by laser interferometer before leaving the factory to ensure a nonlinear error of 0.02%.

2. Closed-loop control application:

In the steam turbine DEH system, the feedback signal of the displacement sensor 0508.902T0201.AW020 and the servo valve form a closed-loop control. When the set opening deviates from the actual opening, the controller adjusts the hydraulic oil flow in real time to shorten the valve response time to 50ms and the control accuracy to ±0.1mm.

In the actual application of power plants, the displacement sensor 0508.902T0201.AW020 plays a significant role in the unit valve control: the valve opening display resolution is increased from 0.5% to 0.01%, and the load regulation rate is increased by 30%. The average annual failure of the sensor is greatly reduced, and the operation and maintenance cycle of the unit is extended from 1 month to 12 months.

The LVDT displacement sensor 0508.902T0201.AW020 perfectly combines the electromagnetic induction principle with precision electromechanical design, not only solving the wear problem of traditional contact sensors, but also redefining the standard of turbine valve control with micron-level accuracy. In the context of the energy industry’s transformation towards high efficiency and low carbon, such high-reliability sensors will become the core cornerstone of smart power plant construction.

When looking for high-quality, reliable LVDT displacement sensors, YOYIK is undoubtedly a choice worth considering. The company specializes in providing a variety of power equipment including steam turbine accessories, and has won wide acclaim for its high-quality products and services. For more information or inquiries, please contact the customer service below:

E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229

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Yellow light XB2-EV445
Driver MGFAS2-DSM-DSC-B/ECR
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FAN RG130/0800-3612-030206
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bolts heater 1.2311(4)-φ18X600
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Blower (fan)for forced air cooling of dry type power transformers GFD580-150
Electrodes (Boiler electrode rod) DJY2612-115
Digital Temperature Monitor WK-Z2T4(TH)
Relay RJ2S-CL-A24 8A 24VAC