Views
2 months ago

WORLD OF INDUSTRIES 4/2019

WORLD OF INDUSTRIES 4/2019

A bridge between two

A bridge between two worlds More and more industrial processes are going digital. It is now also the turn of level measurement with float switches. A float switch for this purpose features a semiconductor sensor. This form of limit level monitoring represents a decisive step towards Industry 4.0. AUTOMATION Virtually no machine or plant manages without them: millions of float switches are employed to monitor liquid levels every single year. They are reliable, simple and robust. Float switches consist of only a few components, which is partly why they are the most economical measuring principle for this type of task. They are mainly used to monitor limit levels and respond if a critical level is reached. Float switches protect against overflow or dry running. This functionality is stipulated for certain tank plants, for example by the German Water Resources Act, to prevent overfilling or leakage of the medium into the groundwater. In industrial applications, float switches monitor limit levels as a precautionary measure: pumps as well as hydraulic or lubrication systems are supplied with the right media on demand or switched off in good time if they run dry, so that no damage can occur, e.g. due to overheating. As effective as necessary, as easy as possible The float switch principle is as simple as it is effective: a float with a builtin magnet moves on a guide tube according to the liquid level in a vessel or tank. At defined measuring points it operates hermetically sealed reed contacts with a normally open, normally closed or change-over function. These mechanical switch contacts are energised by the float’s magnetic field. The switching operation is contact-free and hence also potential-free. Another advantage of this type of measuring instrument is that the float switch can be adapted to the density of the medium in the tank, so that there is no influence on measuring accuracy. The design and operating principle of conventional float switches – including all their positive features – have now been incorporated into the digital version. The new GLS-1000 switch type from Wika replaces the classic reed contact with a semiconductor sensor which, once again, is activated by the magnetic field of the float magnet. This results in a measurable resistance change, which is detected and processed by the electronics, so that an electrical switching signal is tripped in the same way as with a conventional float switch. The digital signal via the PNP / NPN switching output offers an unlimited number of switching cycles. Since no mechanical switching contact is used, the sensor is free from wear and thus extremely durable within its operating limits. Like their conventional equivalents, digital float switches represent a reliable and economical solution. Similar to a classic float switch, the GLS-1000 can be provided with up to four switch points. It has an optional temperature output which can be used, for instance, as a Pt100 / Pt1000 resistance thermometer for monitoring the temperature of the medium. Since the external design and geometry of the device are identical, mechanical float switches are very easy to replace with digital ones. Automating the manufacturing processes of tomorrow The extremely reliable switching function and built-in long service life are not the only arguments for choosing the new switch. Thanks 30 WORLD OF INDUSTRIES 4/2019

to its digital signal processing capabilities, 02 Float switch for industrial applications with the GLS-1000 is an ideal component for circular connector M12 x 1 and cylindrical float automating the manufacturing processes of tomorrow. Depending on the model, it 03 GLS-1000 float switch in a tank can in future be integrated into appropriately automated machine and plant controls, for example using IO-Link 1.1. This is currently only possible with much more expensive level measuring technologies like guided microwave, ultrasound or vibration limit switches. Moreover, the advanced electronics open the door for additional functionalities such as internal diagnostic capabilities, sensor parameterising options or an operational status display. Conclusion 01 Float switch for industrial applications with cable outlet and float from Buna 02 03 With their PNP / NPN switching output signals, long service life and excellent resistance to shock and vibration, float switches with semiconductor sensors provide access to new applications in the field of limit level monitoring. Smarter sensors capable of collecting additional diagnostic and measured data will ensure that in the future, too, float switches are the solution of choice for integration into highly automated processes. At the same time, semiconductor float switches are extremely economical compared to other digital solutions. Yet in spite of this, they are by no means the beginning of the end for tried-and-tested reed contact switches. Owing to their proven reliability, classic float switches will continue to be a good alternative for many applications in tomorrow’s world where the benefits of mechanical switching are decisive – such as potential-free switching or safe isolation of circuits and cables. 01 Photographs: Wika Alexander Wiegand SE & Co. KG, Germany https://en.wika.com

E-PAPER KIOSK:

WORLD OF INDUSTRIES - MOTION, DRIVE & AUTOMATION 1/2017
WORLD OF INDUSTRIES - MOTION, DRIVE & AUTOMATION 2/2017
WORLD OF INDUSTRIES - MOTION, DRIVE & AUTOMATION 3/2017
WORLD OF INDUSTRIES - MOTION, DRIVE & AUTOMATION 4/2017
WORLD OF INDUSTRIES - MOTION, DRIVE & AUTOMATION 5/2017
WORLD OF INDUSTRIES - Industrial Automation 1/2017
WORLD OF INDUSTRIES - Industrial Automation 2/2017
WORLD OF INDUSTRIES - Industrial Automation 3/2017
WORLD OF INDUSTRIES - Industrial Automation 4/2017
WORLD OF INDUSTRIES - Industrial Automation 5/2017