The TR eddy current sensor of aviation Tianrui brand can measure the relative displacement change between the metal conductor surface and the probe surface in static and dynamic non-contact way.

It is a non-contact linear measurement tool. In the state analysis, vibration research, analysis and measurement of high-speed rotating machinery and reciprocating motion machinery, non-contact high-precision vibration and displacement signals can continuously and accurately collect various parameters of rotor vibration state.

Eddy current sensor is widely used in the on-line monitoring and fault diagnosis of large-scale rotating machinery because of its advantages such as good long-term working reliability, wide measuring range, high sensitivity, high resolution, fast response, strong anti-interference force, not affected by oil and other media, and simple structure.

Basic principle of TR eddy current sensor:

Probe, extension cable, proximitor and measured body constitute the basic working system.

The high frequency oscillation current in the proximitor flows into the coil of the probe through the extension cable, generating alternating magnetic field in the coil of the probe head. If there is no metal material close to the effective range of this alternating magnetic field, the energy of this magnetic field will be totally lost; when there is a measured metal body close to this magnetic field, the induced current will be generated on this metal surface, which is called eddy current in electromagnetics.

At the same time, the eddy current field also produces an alternating magnetic field in the opposite direction of the head coil. Because of its reaction, the amplitude and phase of the high-frequency current of the head coil are changed (the effective impedance of the coil). This change is related to the permeability, conductivity, geometry, size, current frequency of the metal body, and the distance from the head coil to the surface of the metal conductor Etc.

Characteristics of TR eddy current sensor:

●Various types and models; Probe diameter:Ф3~Ф60; More than ten kinds of sensor output.

●Excellent performance, linear range: 0.5mm ~ 50mm; it can directly replace 3300 series products of Bentley (BN) Company in the United States.

●Products of the same model can be interchanged.

●Military products.

TR eddy current sensor application:

Tr81 series eddy current sensors are widely used in electric power, petroleum, chemical industry, metallurgy and other scientific research and production units. The radial vibration, axial displacement, key phase, rotation speed, differential expansion, eccentricity of the shaft of large-scale rotating machinery such as steam turbine, water turbine, blower, air compressor, gearbox, large-scale cooling pump and so on, as well as the mechanical research of rotor and the dimension inspection of parts, are measured and protected online.

Typical application diagram:

Axial displacement measurement

For many rotating machinery to measure axial displacement, including steam turbines, gas turbines, turbines, centrifugal and axial compressors, centrifugal pumps, etc. Some faults can also be distinguished:

●Wear and failure of push bearings  ●Wear and failure of balancing pistons

●Loosening of the push flange      ●Locked by coupling, etc.

Relative vibration measurement (large machinery)

To measure radial vibration, it can be used to analyze the working state of the bearing and the imbalance of the rotor. The eddy current sensor system can provide the information needed for mechanical condition monitoring of the following critical or basic machinery:

●Industrial turbine, steam/gas               ●Compressor, radial/axial

●Power generation turbine, steam/gas/water   ●Expander

●Electric motor                              ●Alternator

●Exciter                                     ●Gearbox

●Pump                                        ●Fan

●Blower                                      ●Reciprocating machinery

Relative vibration measurement (small machinery)

Vibration measurements can also be used for continuous monitoring of small, general machinery. The eddy current sensor system provides important information for the early determination of the following mechanical failures:

●Synchronous vibration of the axis  ●Instability of oil film

●Rotor friction                     ●Loose parts

●Loose bearing sleeve               ●Compressor kicking

●Rolling element bearing failure    ●Radial preload, internal / external including misalignment

●Wear of bearing bar alloy      ●Excessive bearing clearance, radial / axial

●Coupling "locked"             ●Wear / failure of balance piston

●Shaft bending                 ●Gear engagement

●Uneven air gap of electric motor   ●Turbine blade channel resonance

Eccentricity measurement

The measurement of eccentricity is very important to evaluate the overall mechanical state of rotating machinery. Especially for the turbine equipped with TSI, eccentricity measurement has become an indispensable monitoring index in the process of start-up or shutdown. The eddy current sensor system measures the degree of shaft bending, which can be caused by:

●Original mechanical bending  ●Bending due to temporary temperature rise

●Gravity bending               ●Bending caused by external force  

Rotation speed measurement

For all optional machines, it is necessary to monitor the rotation speed of the rotating machinery shaft, which is an important indicator to measure the normal operation of the machine. The advantage of eddy current sensor in measuring speed is unmatched by any other sensor. It can not only respond to zero speed, but also respond to high speed, and has strong anti-interference performance.

Expansion difference measurement

For turbo generator unit, due to different metal materials, different coefficient of thermal expansion and different heat dissipation, the thermal expansion of shaft may exceed the shell expansion; it may cause the mutual contact of rotating parts and static parts (such as shell, nozzle, pedestal, etc.) of turbine, leading to the damage of the machine. Therefore, the measurement of differential expansion is very important.

Dynamic monitoring of commutator plate of rolling bearing and motor commutator

It is very important for predictive maintenance of machines using rolling bearings. The probe is installed in the bearing housing to observe the bearing outer ring. As the rolling element is rotating in the bearing, when the rolling element collides with the defective part of the bearing, the outer ring will produce small deformation.

The monitoring system can detect the deformation signal. When the signal is deformed, it means that there is bearing failure, such as the crack defect of rolling element or the defect of bearing ring. It can also measure the movement state of the inner ring of the bearing, and the sliding degree of the bearing can be measured after calculation.