Inductive proximity sensors are designed for wear-free and non-contact detection of metal objects. One of the first sensing technologies developed, these sensors are still widely used today and incorporate a coil wrapped around a ferrite core (see Figure 1), an oscillator, detector circuit and a solid-state output. They generate a high frequency electro-magnetic AC field that interacts with the target.
Figure 1
Ferrous and nonferrous metals affect proximity sensors differently, and are sensed at different ranges depending upon the metal being detected. To sense different metals the sensing range must be adjusted to accommodate what is commonly referred to as a 'correction factor' (see Table 1). Sensor technology and design has evolved to a point where correction factors do not need to be applied: this is widely referred to as 'factor 1' sensing. These factor 1 sensors use multiple coils that detect all metals at the same range without adjustment, giving them a longer sensing range than regular proximity sensors. Instead of a single coil inducing and being affected by eddy currents on a target as in standard proximity sensing, factor 1 sensors use separate, independent sender and receiver coils. Because of this, ferrous and nonferrous metals have the same effect on factor 1 sensors and are rated for the same operating distance.
Not all factor 1 sensors are created equal: some operate using two coils, some three or four; some completely remove the ferrite core (see Figure 2), while others incorporate it into the design. Factor 1 sensors without ferrite cores are inherently immune to magnetic field interference that often occurs during electric welding operations, lifts and electric furnaces. The absence of the ferrite core also allows factor 1 sensors to operate at a higher switching frequency.
Figure 2
Factor 1 sensors have also been developed in multiple housing types to allow for chemical resistance and sudden temperature variations, such as those in food and beverage applications. Some of these sensors can even withstand temperatures ranging from -30°C to 85°C. Factor 1 sensors can be flush or non-flush mountable, although some manufacturers' factor 1 sensors allow only limited recessed mounting.
Figure 3
Though currently not capable of being used in intrinsically safe or analog sensors, factor 1 technology sensors can offer numerous solutions, with extended range, ferrous and nonferrous applications and stocking issues.
Typical correction factors apply to standard inductive sensors when a nonferrous target is being detected.
Figure 4
The correction factors are nominal values. Deviation may be due to variations in oscillator frequency, alloy composition, purity and target geometry.
Enhanced automated weld inspection system
Sensors & Transducers
SmartRay is offering the release of new hardware for its weld inspection system, JOSY, delivering elevated performance and flexibility in the process.
Read more...Leaders in sensor technology Gail Norton Instrumentation
Sensors & Transducers
Photoelectric eyes have always needed perfect working conditions, but in the workplace there is no such thing. Steam, water, light and dirt interfere with most photoelectric eyes, but never with a Telco sensor.
Read more...Easy parameter setting of vision sensors ifm - South Africa
Sensors & Transducers
Contour verification and object inspection are two of the most important functionalities in industrial imaging. With the new O2D5xx series, ifm now offers a solution that perfectly masters both functionalities
Read more...Keeping a close eye on product quality and purity Endress+Hauser South Africa
Sensors & Transducers
Colour measurements are necessary in many processes to avoid product losses and ensure safe production and batching. The Memosens Wave CKI50 process spectrometer from Endress+Hauser is a compact, robust and process-friendly device allowing quality, batching and phase checks to be performed by a single instrument for the entire visible colour spectrum.
Read more...The sensory reaction of building management systems Schneider Electric South Africa
Sensors & Transducers
Today’s building management systems (BMS) cannot function properly without sensors. This is so critical that if sensors start failing, they can become ‘blind’.
Read more...High-precision automated inspection
Sensors & Transducers
Delivering advanced inline metrology to an expanding range of challenging industries, SmartRay is launching the smallest field-of-view 3D sensor of its cutting-edge ECCO X series.
Read more...Long-range laser distance measuring sensor Vepac Electronics
Sensors & Transducers
The MS-100A is a long-range laser distance measuring sensor with a range of 150 to 1000 mm. This sensor excels in applications requiring extended measurement capabilities, such as quality control and logistics.
Read more...Energy measurement module for BL20 I/O System Turck Banner Southern Africa
Electrical Power & Protection
Turck’s BL20 energy measurement module enables precise monitoring of the energy consumption of single- or three-phase systems.
Read more...The power of smart maintenance for securing water supply Omron Electronics
Sensors & Transducers
The water industry plays an essential role in delivering safe drinking water and effective wastewater services to society and various industries. A lack of maintenance could have severe consequences, as even the failure of a single component can significantly impact operations, and maintenance expenses represent a substantial part of the overall costs of water and pumping systems.
Read more...Rotary atomisers for efficient paint spraying Instrotech
Sensors & Transducers
Painting the bodywork is an integral component of vehicle manufacturing. Keller supplied intrinsically safe pressure transmitters and intrinsically safe temperature sensors to a client producing paint robots for the car industry.
printer friendly version