Sensors & Transducers


Hygienic limit switches for processes

February 2019 Sensors & Transducers

Process and storage vessels incorporate limit switches to prevent overfilling of a tank or vessel (full indicator) or dry running of a pump (empty indicator). Anderson-Negele’s NCS series are ideally suited for the reliable measurement of limits in media with low water content, such as certain alcohols and cosmetics, providing universal application in bottling and pharmaceutical applications.

Capacitive working principle

Anderson-Negele level switches operate on the basis of the capacitive working principle. The measuring electrode, the medium and the conductive wall of the tank form an electrical capacitor influenced by three main factors: distance; area of the electrode surfaces; andtype of medium between the electrodes.

The measuring electrode and the tank wall serve as the capacitor plates while the medium acts as the dielectric fluid. Due to the higher dielectric constant of the medium relative to air, the capacity increases when the electrode is immersed in the medium. Exposing the electrode has the opposite effect. The change in capacity is analysed by the level switch and converted to a corresponding switching command. The sensor outputs a 24 V DC signal (active output). The minimum and maximum (full/empty) switching functions can be swapped by reversing the polarity of the power supply. The capacitive working principle requires that the sensor tip, which is made of PEEK, be completely immersed in the medium. The advantage is that the sensor does not respond to foam or adherences and a signal is emitted only when the medium reaches the level. Capacitive measurement is most reliable when the dielectric conductivity and temperature of the medium are constant. Changes in the outer conditions are generally non-critical in media with high dielectric constant values.


Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Large German fertiliser manufacturer reduces costs thanks to SICK Automation
February 2019, SICK Automation Southern Africa , Sensors & Transducers
Available agricultural land in Europe is limited. As a result, large quantities of fertiliser are used in order to increase yields. Producing fertiliser, however, is an energy-intensive process which ...

Read more...
Traceability for tobacco manufacturer
February 2019, SICK Automation Southern Africa , Sensors & Transducers
SICK Automation South Africa recently installed 120 image-based 2D barcode readers across multiple scanning stations in a South African tobacco manufacturing plant. The cigarette manufacturer was looking ...

Read more...
A new standard for digital ­inclination measurement
February 2019 , Sensors & Transducers
A new standard for digital inclination measurement has been set with the latest digital protractors from Stabila. Both the Tech 500 DP and Tech 1000 DP are manufactured exclusively in Germany, the main ...

Read more...
Bromide sensor for water disinfection
February 2019, ASSTech Process Electronics + Instrumentation , Sensors & Transducers
With the expansion of its product range of membrane-covered amperometric digital sensors for liquid analysis, ASSTech now has available the Jumo tec-Line Br bromide sensor for general water disinfection ...

Read more...
Wenglor expands optical sensor range
February 2019, ASSTech Process Electronics + Instrumentation , Sensors & Transducers
Wenglor’s PNG/smart generation of photoelectronic sensors is distinguished by a combination of performance and communication. An aligned optical axis and a balanced switching point, as well as large switching ...

Read more...
Four questions to ask when ­choosing a vision solution
February 2019, Turck Banner , Sensors & Transducers
Many users find vision systems challenging and it can be difficult to know where to start, but there are some simple steps that can help to match the right vision solution to an application. This article ...

Read more...
Intelligent valve sensor
February 2019, ifm Electronic RSA , Sensors & Transducers
The intelligent valve sensor for pneumatic quarter-turn actuators from ifm electronic features 360° position monitoring to allow precise and continuous scrutiny of the valve condition. Problems such as ...

Read more...
Fast optical data transmission
February 2019, Countapulse Controls , Sensors & Transducers
The Leuze DDLS 500 optical data transceiver has a high optical transmission rate of 100 Mbit/s. This photoelectric sensor allows data transmission without cabling and without interference. Gerry Bryant, ...

Read more...
Speed sensor with IO-Link
February 2019, ifm Electronic RSA , Sensors & Transducers
The new range of speed sensors from ifm electronic has the evaluation electronics integrated into the sensor housing. This allows for low cost and easy monitoring or rotating, as well as linear movements ...

Read more...
Collision avoidance in reverse gear
January 2019, ifm Electronic RSA , Sensors & Transducers
To avoid collisions during manoeuvring, ifm electronic offers an automatic collision avoidance system: a 3D camera mounted at the back of a vehicle monitors the rear area, detects objects in the travel ...

Read more...