In the operation of modern large-scale steam turbine units, the overspeed protection system, as a key safety protection device, can effectively prevent serious accidents caused by excessive speed of the unit. As an important part of the overspeed protection system, the accuracy and reliability of the output signal of the CS-2-100-02 speed sensor are directly related to the effectiveness of overspeed protection. This article will focus on how to judge whether the steam turbine overspeed protection is normal through the output signal of the CS-2-100-02 speed sensor.

Working principle and signal characteristics of CS-2-100-02 speed sensor

The CS-2-100-02 speed sensor is a non-contact electromagnetic induction speed sensor, which belongs to the magnetoresistive or magnetoelectric sensor and is specially used to measure the speed of magnetic conductive materials. Its working principle is based on the change of magnetic flux caused by the rotation of gears. When the magnetic conductive material (such as gear teeth) passes through the sensor head, the magnetic flux changes, and the coil inside the sensor induces an electrical signal, and outputs a square wave signal after being processed by the internal circuit.

The CS-2-100-02 speed sensor has the following features:

• • Non-contact measurement: No direct contact with the object to be measured is required, reducing mechanical wear and the risk of failure.
• • Active sensor: No external power supply is required, with high measurement accuracy and good anti-interference, suitable for harsh environments.
• • High measurement accuracy: It can provide accurate speed measurement to ensure the accuracy of overspeed protection.
• • Output square wave signal: The output signal is a square wave, and the frequency is proportional to the speed, which is convenient for signal processing and analysis.
• • Installation gap: The installation gap can reach 2mm, which is suitable for low speed monitoring.

Steam turbine overspeed protection mechanism

The steam turbine overspeed protection system prevents the unit from overspeeding by monitoring the steam turbine speed and triggering the protection action when the speed exceeds the set value. Overspeed protection usually includes the following types:

• • OPC (overspeed protection controller): When the speed reaches 103% of the rated speed, the OPC acts, closes the regulating valve, and reduces the turbine speed.
• • DEH (digital electro-hydraulic control system) overspeed protection: When the speed reaches 110% of the rated speed, the DEH overspeed protection triggers the AST solenoid valve and performs an emergency shutdown.
• • Mechanical overspeed protection: As a backup protection, when the DEH overspeed protection fails, the mechanical overspeed protection is activated to achieve an emergency shutdown.

The overspeed protection system usually consists of a speed sensor, a speed card, a monitoring and protection instrument, etc. The speed sensor is responsible for measuring the turbine speed, the speed card is used for signal processing and conversion, and the monitoring and protection instrument is used for speed monitoring and protection logic judgment.

Judgment of overspeed protection status based on CS-2-100-02 output signal

By analyzing the output signal of the CS-2-100-02 pickup speed sensor, it can be determined whether the overspeed protection system is working properly. The specific steps are as follows:

1. Check the sensor output signal:

Use an oscilloscope or speed monitor to check whether the sensor output signal is a normal square wave signal. Verify whether the signal frequency corresponds to the turbine speed. Check whether the signal is stable and whether there is interference or abnormal fluctuation.

2. Verify signal transmission:

Check whether the line from the sensor signal to the speed card and the monitoring and protection instrument is normal. Verify whether the speed displayed by the monitoring and protection instrument is consistent with the sensor output signal.

3. Test the overspeed protection logic:

Test whether the logic of the overspeed protection system is triggered correctly by simulating the overspeed signal. Verify whether the OPC and DEH overspeed protections operate normally at the set speed. Check whether the emergency stop action is reliably executed.

4. Monitoring system related:

Speed ​​card is used in the DEH system to monitor the speed and trigger overspeed protection. The sensor speed CS-2, used to monitor parameters such as speed and zero speed, and output signals to the DEH/DCS.

5. Signal type and anti-interference:

The output signal type of the CS-2 is a square wave, which has good anti-interference ability and ensures the accuracy of the signal. Maintenance and testing recommendations

To ensure the reliability of the overspeed protection system, the CS-2-100-02 raotaional speed sensor needs to be checked and tested regularly:

• • Regularly check the sensor installation gap and line connection to ensure normal signal transmission.
• • Regularly use a speed monitor or oscilloscope to check the sensor output signal to verify its accuracy and stability.
• • Regularly perform overspeed protection logic tests to verify the reliability of the protection action.
• • Pay attention to the working environment of the sensor to ensure it is clean and dry, and avoid oil and dust.

When looking for high-quality, reliable rotational speed 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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