Eddy current displacement sensors from Micro-Epsilon occupy a special position amongst inductive displacement sensors. Insensitive to environmental influences such as temperature, pressure and dirt, they measure displacement, distance and position with high accuracy. The compact eddyNCDT 3001 model now offers even larger measuring ranges, thereby opening up new fields of application.
Eddy current sensors from Micro-Epsilon are unique among inductive measuring techniques. They provide reliable measurement results even in harsh, industrial environments at the highest precision and high bandwidth. Measuring via eddy current is based on the extraction of energy from an oscillating circuit. This energy is needed for the induction of eddy currents in electrically-conductive materials. Here, a coil is supplied with an alternating current, causing a magnetic field to form around the coil. If an electrically conducting object is placed in this magnetic field, eddy currents are induced which form a field according to Faraday‘s induction law. This field acts against the field of the coil, which also causes a change in the impedance of the coil. This impedance can be calculated by the controller by looking at the change in the amplitude and phase position of the sensor coil.
The principle can be used for measurements of all electrically conductive materials. The special coil wrapping of the Micro-Epsilon sensors enables very compact sensor designs, which can still be used across high temperature ranges. As eddy current penetrates insulator materials, even metal behind an insulating layer can be used as a measuring object.
Even dust, dirt and oil do not affect the measurement. This immunity combined with the sensor’s robust, temperature-resistant design enable highly precise measurements in harsh, industrial environments.
Inductive sensors based on eddy currents now offer even more flexibility
The eddyNCDT 3001 series is specially designed for applications where conventional, inductive displacement sensors have often reached their performance limits. Their compact dimensions have to date only been reserved for inductive sensors and proximity sensors. This compact sensor with integrated electronics stands out due to easy operation. In addition to the M12 housing, the powerful eddyNCDT 3001 eddy current sensors are now also available with an M18 housing covering measuring ranges from to 2mm to 8mm. These ranges open up new areas of use. The sensors are protected to IP67 and so are universally applicable in automation, machine building and machine design. Furthermore, these sensors are temperature-compensated up to 70°C. As the sensors are easy to use and provide an excellent price/performance ratio, they are particularly suitable for high volume and OEM applications as well as for salt water in offshore/marine applications. The high measurement accuracy and linearity as well as the high frequency response rate of 5 kHz are outstanding characteristics compared to conventional inductive sensors in the same price class. eddyNCDT sensors are factory-calibrated for ferromagnetic and non-ferromagnetic objects such as aluminum and steel. Customer-specific adaption to other materials is also possible.
Oil gap in hydrostatic bearings
Eddy current displacement sensors are for example used in large plant and machinery such as stone mills or telescopic installations which often work with hydrostatic bearings. These bearing systems are continuously supplied with liquid lubricant via an external pressure supply. The lubricant is pressed between the bearing surfaces, which are therefore continuously separated from one another by a thin lubricant film. The bearing surfaces are not exposed to any friction and hence operate wear-free. This enables sub-micrometer position control. Any disturbances in the hydraulics or pressure drops can have disastrous consequences, which could result in damage to the bearings and ultimately system failure, causing high maintenance and repair costs. The oil gap in hydrostatic bearings must therefore always be inspected reliably, which is possible by using the eddyNCDT 3001 eddy current sensor. The compact sensor is mounted horizontally to the bearing shoe and so is not directly exposed to oil pressure in the bearing. It measures through the oil film onto the opposing bearing surface. eddyNCDT 3001 sensors are easy to install and so are also suitable for ageing plants that need to be retrofitted.
Micro-Epsilon has developed the eddyNCDT 3005 for integration into plant and machinery. The eddyNCDT 3005 is a new, powerful eddy current measurement system for fast, high precision displacement measurements. It provides ease of use and high measurement accuracy, offering an outstanding price/performance ratio. Therefore, the sensor is ideally suited to OEM integration and mechanical engineering applications. The system comprises a compact M12 controller, a sensor and an integrated cable and is factory-calibrated for ferromagnetic or non-ferromagnetic materials. eddyNCDT 3005 sensors and controller are temperature-compensated, which is why high measurement accuracies can be achieved even in fluctuating temperatures. The sensors are designed for ambient temperatures up to max. +125°C but can optionally be custom engineered for temperatures from -30°C to 180°C. The measurement system is pressure-resistant up to 10 bar. Where high volume orders are required, customer-specific designs can be tailored to suit individual requirements.
eddyNCDT sensors offer extremely precise measurements and are used where micron accuracies are required. Being used in ambient temperatures from -40°C to more than 200°C, the eddy current displacement sensors are robust against temperature fluctuations.
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