Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question dated 2020-09-09

1. Accuracy of serial measurement of the shaft. 2. The zero position is determined, with the zero reference position being accurately set. 3. Install the probe, adjust the gap between the probe and the shaft, and secure the probe once the gap voltage reaches the zero voltage level.

When the unit is in operation, the rotor experiences axial displacement due to its inherent properties. To measure the magnitude of this axial displacement, shaft displacement sensors are installed on the unit, along with alarms and interlock systems for shutdown. When the axial displacement exceeds the preset threshold for shutdown, the control system activates the interlock mechanism to shut down the unit safely, thereby protecting it. In this process, the measurement of shaft displacement is extremely important. Only by correctly installing the shaft displacement sensor can accurate data on shaft displacement be obtained, enabling the monitoring of the unit. In case of abnormal conditions, it triggers the interlock shutdown mechanism for shaft displacement, ensuring the safe shutdown of the unit. The following discusses how to properly install the shaft displacement probe. The measurement of the shaft displacement of the turbine unit is generally carried out using eddy current sensors. The measurement principle involves an electrodynamic induction sensor and a preamplifier working together to form a high-frequency oscillator. The amplitude of this oscillator changes depending on the distance between the sensor probe and the metal surface being measured, with this amplitude being directly proportional to that distance. This amplitude is then used by a displacement transmitter to convert axial displacement into a corresponding standard signal, which is fed into the control system to enable the measurement and control of the shaft displacement of the machine.

When the unit is in operation, the rotor experiences axial displacement due to its inherent properties. To measure the magnitude of this axial displacement, shaft displacement sensors are installed on the unit, along with alarms and interlock systems for shutdown. When the axial displacement exceeds the preset threshold for shutdown, the control system activates the interlock mechanism to shut down the unit safely, thereby protecting it. In this process, the measurement of shaft displacement is extremely important. Only by correctly installing the shaft displacement sensor can accurate data on shaft displacement be obtained, enabling the monitoring of the unit. In case of abnormal conditions, it triggers the interlock shutdown mechanism for shaft displacement, ensuring the safe shutdown of the unit. The following discusses how to properly install the shaft displacement probe. ? ?? ? The measurement of the shaft displacement of the turbine unit is generally carried out using eddy current sensors. The measurement principle involves an electrodynamic induction sensor and a preamplifier working together to form a high-frequency oscillator. The amplitude of this oscillator changes depending on the distance between the sensor probe and the metal surface being measured, with this amplitude being directly proportional to that distance. This amplitude is then used by a displacement transmitter to convert axial displacement into a corresponding standard signal, which is fed into the control system to enable the measurement and control of the shaft displacement of the machine.

1. To determine the zero voltage, rotate the probe slowly to prevent damage to it due to excessive rotation. 2. Make sure the extension cable rotates as well, to avoid excessive twisting that could cause damage

1. Axle alignment: After the unit is installed, the value of the axle alignment is extremely important; it must be determined through repeated and precise measurements by maintenance personnel, as it serves as the basis for the installation of sensors. 2. Which end the shaft is directed to: the zero position is determined. When installing the probe, the instrument operator must be clear as to which end the shaft has been directed to – that is, whether it has been directed to the main thrust end or the auxiliary thrust end – this must be absolutely clear. Only in this way can the zero point position be determined. 3. How many probes are there: There’s no need to explain this; it’s obvious. 4. Displacement interlock logic: Before installing the probe, it is essential to have a thorough understanding of the displacement interlock logic, including whether there are backups available and whether it involves single-point or multi-point interlocking.

1. Accuracy of serial measurement of the shaft. 2. The zero position is determined, with the zero reference position being accurately set. 3. Install the probe, adjust the gap between the probe and the shaft, and secure the probe once the gap voltage reaches the zero voltage level.

When the unit is in operation, the rotor experiences axial displacement due to its inherent properties. To measure the magnitude of this axial displacement, shaft displacement sensors are installed on the unit, along with alarms and interlock systems for shutdown. When the axial displacement exceeds the preset threshold for shutdown, the control system activates the interlock mechanism to shut down the unit safely, thereby protecting it. In this process, the measurement of shaft displacement is extremely important. Only by correctly installing the shaft displacement sensor can accurate data on shaft displacement be obtained, enabling the monitoring of the unit. In case of abnormal conditions, it triggers the interlock shutdown mechanism for shaft displacement, ensuring the safe shutdown of the unit. The following discusses how to properly install the shaft displacement probe. ? ?? ? The measurement of the shaft displacement of the turbine unit is generally carried out using eddy current sensors. The measurement principle involves an electrodynamic induction sensor and a preamplifier working together to form a high-frequency oscillator. The amplitude of this oscillator changes depending on the distance between the sensor probe and the metal surface being measured, with this amplitude being directly proportional to that distance. This amplitude is then used by a displacement transmitter to convert axial displacement into a corresponding standard signal, which is fed into the control system to enable the measurement and control of the shaft displacement of the machine.

1. Accuracy of serial measurement of the shaft. 2. The zero position is determined, with the zero reference position being accurately set. 3. Install the probe, adjust the gap between the probe and the shaft, and secure the probe once the gap voltage reaches the zero voltage level.

1. To determine the zero voltage, rotate the probe slowly to prevent damage to it due to excessive rotation. 2. Make sure the extension cable rotates as well, to avoid excessive twisting that could cause damage