Breaking new ground
By H Sack, VEGA
Electricity+Control February 2014 (pages 36 – 37)
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Tried and tested analogue limit switches are being replaced by digital technology and these devices are more commonly called ‘point level sensors’. Point level measurement is closely related to level measurement.
Level measurement is used to describe continuous measurement of a changing level, whereas point level measurement is used to indicate a discrete condition, i.e. the existence of the level at a certain point. Level sensors and point level sensors are often combined in one application, depending on the customer requirement. Usually, when both level sensors and point level sensors are installed, it is to increase safety - for example in the chemical industry.
In modern level sensors and point level sensors, microprocessor technology enables numerous functions that monitor the electronics as well as the sensing element during operation. Until now, all devices in a system were analysed individually from safety-engineering standpoint, but today, engineers look at the entire measurement chain from the sensor to the transmission of measured values to the actuating components (valves, pumps, etc).
A new vibrating level switch is available that has been designed for use in temperatures up to 450°C and as low as -195°C and pressures from -1 to 160 bar. Previously used piezoelectric drives have been replaced with a special solenoid that drives the tuning fork and is able to withstand the high temperatures. Ceramic materials and secure electrical connections operate at 450°C and high pressure resistance is achieved through the mechanical stability of robust materials that withstand pressures up to 160 bar.
- A new vibrating level switch is available.
- When both level sensors and point level sensors are installed, it is to increase safety.
- Microprocessor technology enables numerous functions in modern level sensors and point level sensors.