Low-profile level sensor
Feb 2000
Level Measurement & Control
Shorrock Automation
The new KNQ capacitive level sensors from sensing and control specialist, IFM Electronic, have regular rectangular bodies with a low profile, allowing them to fit almost flush against tank and vessel walls. This low-profile mounting arrangement makes the sensors far less vulnerable to damage than conventional cylindrical sensors used in though-the-wall level control applications.
The implementation of 'charge-balance technology' makes these new sensors virtually immune to the effects of electrical interference. IFM Electronic says that capacitive switches with this innovative sensing technology are the only ones that meet the current generic standards for EMC performance.
Speedy, accurate adjustment of KNQ sensors is made simple by the IFM Teach-In system. Users activate the Teach-In system by bringing a screwdriver or similar metal object close to the Teach-In element with the vessel empty or, depending on the application, full. The sensor then automatically optimises its own operating point.
A separate programming wire is also provided so that, as an alternative to local adjustment, setting can be initiated remotely. Whichever method of adjustment is used, an electronic locking system prevents unauthorised tampering with the sensor setting.
Correct adjustment and operation is confirmed by a 3-LED status display. A green LED shows that the sensor is ready for operation while a yellow LED shows the state of the output. A red LED flashes if the sensor detects a potential fault condition, such as a build-up of material on the vessel wall which might affect reliable sensing. A function-check output is provided to give an electrical warning when the red LED is flashing.
The sensors are suitable for use with DC supplies in the range 10 to 36 V. Outputs which are rated at 150 mA, are available as PNP or NPN and they can be programmed for normally open or normally closed operation. Housings are manufactured from damage-resistant PBTP polycarbonate material and the product has an IP67 protection rating.
Shorrock Automation
(012) 346 1594
[email protected]
www.smartnet.co.za/shorrock
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