Innovative Capacitive Sensors for Industrial Use
Published on : Tuesday 31-10-2023
How capacitive sensors help achieve high precision with non-contact measurement in harsh industrial applications.
Capacitive displacement sensors are still deemed to be primarily suited to clean, dry environments. However, in the form of industry-optimised models such as those designed by Micro-Epsilon, capacitive sensors achieve peak performances in harsh industrial applications. They also measure with the highest precision down to sub-micrometer accuracy in industrial environments. With temperature resistance, robustness and flexibility, capacitive sensors can also be used in environments where fluctuating temperatures or magnetic fields occur.
Capacitive displacement sensors mainly determine changes in displacement and position of conductive objects. Here, Micro-Epsilon applies its expertise in the development of innovative capaNCDT sensors from 50 years of company history. This is how these sensors, which originally were assigned to clean environments, have become stable, high precision measuring systems for industrial applications.
Micro-Epsilon also offers different Sensor designs for different fields of application, More precision with triaxial design and patented miniature plug.
Insensitive to magnetic fields: air gap measurement in large electric motors
The advantages of industry-optimised sensors become evident, among other things, with large electric motors such as those found in rock grinding mills for cement production or for mining. The runout of these systems must be permanently monitored. With diameters of more than 10 m, the motors are badly damaged when the rotor touches the stator. This is why the air gap, i.e. the distance between the rotor and stator, is monitored using capacitive displacement sensors. Due to the triaxial design and the non-ferromagnetic materials used such as titanium or stainless steel, the changing magnetic fields have no influence on the measurement result. Due to the non-contact measuring principle, there is no physical impact onto the sensor or measurement object, which provides long-term stability. Different sensor designs, including flat sensors, also enable easy installation in these harsh environments, which only offers a small mounting space requiring sensors with a maximum height of 2.5 mm. Another challenge is the large cable length which should usually be about 8 m.
Space research: capacitive sensors measure under extreme temperature conditions
The extraordinary temperature stability of sensors is demonstrated by measurement tasks for space research. In areas away from the sun, the lowest temperatures are down to -271°C, which is just above absolute zero and therefore in the cryogenic temperature range. However, in trajectories where the components face the sun, they become extremely hot with temperatures rising rapidly to more than 200°C. In addition, rather than the Earth's atmosphere, vacuum prevails. All components that are used in space travel missions must withstand these extreme conditions.
Almost no other system is able to detect linearity deviations up to 0.005% and better across the whole measuring range. Despite comparatively high conduction capacities up to 1nF (1x10e-9 F), the measurement capacity can be resolved to approx. 0.25aF (0.25*10e-18 F), a relation of 1:4,000,000,000. This is achieved with the corresponding subtleties in the high quality components, from the sensor via the sensor connection cable to the controller.
Advantages at a glance:
- Highest precision with subnanometer accuracy
- Excellent temperature stability
- Use in ultra-high vacuums and clean rooms
- Use in industrial environments, certification according to protection class IP67
- Enormous application versatility from semiconductor industry via air gap measurement of large motors to deformation measurement of brake discs or positioning of machines
- The perfect sensor for each measurement task
- Easy to replace: all sensors can be operated without calibration effort with all controllers.
- Ease of use via web interface
- Modular, synchronisable multi-channel controller available
- Up to eight measurement channels.
Micro-Epsilon India Private Limited, Pune. Tel.: +91 20 4913 1030. Fax: +91 20 4913 1001. Email: [email protected]