In the operation and management of large rotating machinery, steam turbines are core power equipment, and real-time monitoring and rapid response of their vibration status are directly related to the safety and economy of the unit. With its high-precision measurement and intelligent control characteristics, the HZD-W/L dual-channel vibration monitor has become a key component of the vibration protection system in modern industry. Through deep integration with the distributed control system (DCS), the device has built a full closed-loop control link from data acquisition to execution protection, realizing automatic load reduction and shutdown protection under vibration over-limit conditions, providing important guarantees for the safe operation of the unit.

1. The basis of vibration data acquisition and processing of HZD-W/L

The vibration monitor HZD-W/L adopts a dual-channel independent monitoring architecture, which can synchronously collect vibration signals in the vertical and horizontal directions of the turbine bearing seat. Its core working principle is based on the electromechanical conversion characteristics of the magnetoelectric speed sensor or eddy current sensor. After converting the mechanical vibration into an electrical signal, it is digitized through the built-in 14-bit high-resolution A/D converter17. The measurement range covers vibration displacement of 0-500μm and vibration intensity of 0-50.0mm/s, meeting the full-condition monitoring requirements of steam turbines from steady-state operation to transient impact.

The intelligent algorithm configured in the system can dynamically compensate the original signal, automatically correct the measurement error caused by temperature drift and time drift, and ensure the display accuracy of ±0.5%. Through the free switching function of vibration intensity and displacement, the operator can select the most suitable monitoring mode according to the characteristics of the unit, such as using displacement monitoring under low-frequency vibration-dominated conditions, and switching to intensity monitoring under high-frequency vibration scenarios, thereby improving the sensitivity of abnormal identification.

2. Data communication and threshold control of DCS linkage

The data interaction between the vibration monitor HZD-W/L and the DCS system relies on two types of core interfaces: analog output and switch output. The 4-20mA current output module linearly maps the real-time vibration value to the standard industrial signal, and realizes the continuous upload of vibration data through the analog input card of the DCS. This design not only supports the long-term recording and analysis of vibration trends by the DCS system, but also provides dynamic input parameters for the automatic control logic. For example, when the vibration value approaches the first-level alarm threshold, the DCS can start the auxiliary cooling system in advance to reduce thermal stress and achieve preventive adjustment.

At the level of protection logic triggering, the dual-channel relay output configured by the vibration monitor HZD-W/L plays a key role. The two-level alarm thresholds preset inside the equipment (I value is warning, II value is danger) are dynamically managed through programmable logic. When the vibration value continues to exceed the II value setting and reaches an adjustable delay of 1 to 60 seconds, the relay contacts close and send a passive dry contact signal to the DCS. This delay mechanism effectively avoids false operations caused by transient interference, while ensuring a rapid response to continuous abnormal conditions. After receiving the signal, the DCS will perform hierarchical control according to the preset protection strategy: the first-level alarm triggers a linear load decrease (such as a 5% reduction in rated load per minute), and the second-level alarm directly starts the shutdown sequence, cuts off the turbine steam inlet valve and puts the turning device into operation.

3. Multiple protection design for system reliability

To ensure the reliability of linkage protection, the vibration monitor HZD-W/L integrates multiple self-diagnosis and redundant control functions. The built-in power-on self-test module of the device can perform periodic diagnosis on the sensor circuit and signal processing unit. When the sensor is disconnected or the signal is abnormal, the alarm output circuit is immediately cut off and the equipment fault code is sent to the DCS to avoid the wrong signal triggering the protection action. In addition, the cross-validation mechanism of dual-channel data significantly improves the monitoring accuracy-when the deviation of the measured values ​​of the two channels exceeds 15%, the system automatically enters the data review mode, and eliminates interference factors such as loose sensor installation or local resonance through spectrum analysis.

On the DCS side, the protection logic adopts a three-out-of-two voting mechanism to enhance the reliability of decision-making. The vibration data from the dual channels of the vibration monitor HZD-W/L are jointly analyzed with the signals of third-party vibration probes (such as axial displacement monitors). The final protection action will only be executed when at least two independent signal sources exceed the limit at the same time. This design effectively avoids unplanned downtime caused by the failure of a single sensor and reduces the probability of false operation to less than 0.1%.

4. Engineering Application and Performance Verification

The application case of a 660MW supercritical unit shows that the DCS protection system with integrated vibration monitor HZD-W/L successfully identified the failure of low-pressure rotor dynamic balance. When the vibration value quickly climbed from 45μm to 182μm within 12 minutes, the DCS stepped down the load from 600MW to 350MW based on the warning signal of HZD-W/L, which bought time for fault diagnosis for the operation and maintenance personnel. After the subsequent vibration continued to deteriorate to the II value threshold (200μm), the system completed the valve closing and generator decoupling within 2 seconds, avoiding the occurrence of shaft collision accidents.

The deep collaboration between the HZD-W/L dual-channel vibration monitor and the DCS system marks the transformation of rotating machinery protection technology from passive response to active defense. Through precise data perception, reliable logical judgment and rapid execution response, the system builds a multi-dimensional protection network for the safe operation of steam turbines. In the future, with the further application of adaptive control algorithms and digital twin technology, the vibration protection system will show stronger adaptability to working conditions and intelligent decision-making features, and continue to promote the improvement of the safety level of power production.

When looking for high-quality, reliable vibration monitors, 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

Yoyik offers various types of spare parts for steam turbines, generators, boilers in power plants:
surface thermal resistance WZPM2-001D
BRAUN MONITOR MODULE E1610
OIL FILTER DP TRANSMITTER VL5GW2.1/123A5
vibration monitor CZJ-B3
Human Interface Module 20-HIM-A6
Ammeter PA194I-9D4
Fuse XPRNT1
Low Resistance Sensor SZCB-02
Electromagnetic brake SDZ1-04
PRESSURE GAUGE RANGE 0~1.6MPA YTN-100
Fire detection sensor IR7200A
Differential pressure transducer BPSN4KB25XFSH2
Current Transformer 11kV (3TA 4TA) AS12/175B/2S
Springs XY2CZ702
Fuse NT4a
MCB 1P IC65N D 16A
Turnbuckle XY2CZ404
Transformer Coil Temperature Device EM5 BWR-04
Transformer Input 900075.001
SWITCH LEVEL L3541CR-RH
HP LVDT SPRAY POSITION SENSOR BY PASS TD-1-150
Thermometer WSS 581W Dial 150mm
Armor Sensor EZ1081-07-00-010 & EZ1901-090
Coal feeder integrator 6105
Heater Element D-59mm L-450mm
Transducer DBSQ 231
RTD sensor WRNR3-18 300*6000-3K-NiCr-Ni
sensor PR9628/011-100
Furnace tube leakage sensor BLD-3B
FUSE XRNP1
Double branch thermistor WZPM-231
Pneumatic Positioner F001798154
High Frequency Modules PL-M20 (110V)
Single phase capacitor motor YY7015-4P