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Eddy current probes offer high resolution

Eddy current probes offer high resolution When you're faced with the challenge of non-contact measurements on metallic targets, eddy current transducers can offer an effective solution. With such devices, an oscillating circuit generates magnetic field lines, and these induce eddy currents on the surface of conductive objects. These interact with the sensor's magnetic field lines, attenuating the amplitude of the oscillating circuit. Thus, the device can produce an output which is proportional to distance.

Applications are many and varied. Perhaps you need to perform distance measurements on metallic objects with intermediate non-conductive media such as polymers, glass, oil, water or dirt. The devices are also excellent for vibration and oscillation detection on rotating shafts.

Measurement of out-of-roundness and radial displacement is also possible, as well as monitoring of rotating mechanical components. You can also check bearing wear and lubrication gap.

In gear applications, eddy current sensors can be used to monitor deformation and oscillation of gearwheels in operation, axial thrust measurement of helical cut gears under load, and detection of tooth loss on gear wheels.

Eddy current sensors are also ideal for thickness measurement of sheet materials and foils, or for weld monitoring applications such as seam positioning via edge detection, welding torch tracking and out-of-roundness measurement on welded drums and tubes. On machines such as gearboxes, engines and turbo generators, eddy current sensors can measure housing deformation under load, thermal expansion, and torsion on shafts and housings.

To address such applications where high resolution and high dynamics are vital, Sensors UK has launched the TX series of eddy current probes. These offer resolution up to 20nm which enables the smallest of amplitudes to be detected, and dynamic performance of 124kS/s, enabling for example their use in vibration or oscillation detection applications on even the fastest rotating systems. Linearity is better than 0.1%.

The probes are designed for temperatures up to 185°C, and are optimised for the entire temperature range with regard to temperature drift, thanks to a proprietary thermal finishing procedure.

Fully digital, the TX series transducer modules are available in single- or two-channel versions, and incorporate USB, CAN and high-speed analogue interfaces. The USB interface is designed for connection to a PC, where users can take advantage of the eddyLAB software which offers oscilloscope, FFT and data logging functions. The eddyLAB software can also be used to define the corner frequency of a low pass filter and to scale the analogue output.
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