SENSORS


reached. In a common welding application, inductive proximity sensors confirm the position of parts to be welded or ensure that powered welding clamps are closed correctly. They are often within a few centimetres of the field source – typically a welding cable carrying currents, which may reach 15kA – and this tends to be the case whether the process requires a continuous weld or a short- duration, high-energy pulse. Most automated welding processes fall into


one of two categories: ‘traditional’ 50Hz mains-powered welding, or the more recent (and more efficient) 1kHz medium-frequency (MF) welding. In each case, the welding currents create electromagnetic fields of the corresponding frequency generating an extreme electromagnetic-interference (EMI) challenge for electronic devices operating around the welding areas. Square-wave field strengths can reach 40 millitesla (mT) for the 50Hz technology and 200mT for MF welding processes. These fields are strong enough to cause non-robust inductive sensors to malfunction owing to their interaction with the oscillator’s field; in particularly challenging situations, permanent damage to discrete components of the sensor electronics may occur. Contrinex inductive proximity sensors were the first to benefit from the advantages of an ASIC design, and will resist such environments, while the newly launched Weld-Immune range is guaranteed to function flawlessly in these extreme electromagnetic fields.


Weld-field immunity Weld-field immunity in inductive sensors is a


further step forward, using Condet technology from Contrinex, developed to revolutionise the inductive sensor world. While these sensors embody inductive technology, the coil, which generates the magnetic field is not part of the oscillator circuit. Instead, an on-board pulse generator causes periodic, short-duration transmitter current pulses to flow through the coil, generating an alternating sensing field with a


square waveform (see Figure 1). This field induces a voltage in the target, which, in turn, generates a current flow in it. When the transmitter current pulse is switched off, the current in the target dies away, causing a voltage to be induced in the transmitting coil. This voltage generates the signal required, and is, in principle, independent of the energy loss in the sensing field. This technology allows the sensor, including


its sensing face, to be fully encapsulated in a one-piece protective housing, machined from V2A/AISI 303 stainless steel – with the added benefit of extended sensing distances (up to 40mm). The sensing circuit also performs equally well with steel and aluminium targets; no reduction factor is required. The high-performance Series 700 Extreme range, resistant to shock, was the foundation for the new Weld-Immune range. Indeed, by tuning its Condet principle to the weld-field- specific EMI environment, Contrinex was able to achieve weld-field immunity not only for the 40mT fields of historic 50Hz welding machines, but also the much stronger fields created by modern 15kA MF welding equipment.


Weld spatter immunity Condet oscillator-free technology already


allows Weld-Immune sensors to ignore small debris and slag that accumulate on the sensing face over time. However, weld- spatter accumulation is also a problem as it hinders the correct orientation of the sensor and can create a protruding layer that collides with the target object. Contrinex sensors can benefit from an ACTIVSTONE coating that, thanks to its ceramic composition, creates a non-stick surface where spatter can’t accumulate. Additionally, and unlike other industry coatings, ACTIVSTONE resists high temperatures over long periods of operation and withstands frequent aggressive cleaning with wire brushes and dry ice. Unsurprisingly, with attention to detail at the


core of Contrinex Swiss quality, the Weld- Immune range has been validated under the most extreme conditions in both laboratory and automotive field-testing.


Figure 1: Sensor block diagram


Complete range and accessories Conscious of the continually evolving


challenge presented by welding applications, in July 2021 Contrinex released a brand-new line of cost-effective Weld- Immune sensors in the form of the Series 600 increased distance family with a PEEK sensing face, covering a new range of applications. Finally, Contrinex provides a full range of accessories that match the quality and robustness of its Weld-Immune sensors; purpose-designed mounting brackets allow fast and precise sensor installation, while high-temperature PUR cables with optional additional protective tubes resist weld spatter. The days of the consumable sensor and sacrificial cables are over; engineers now design new welding lines with durable, high-quality fit-and-forget products, allowing dramatic savings of time and money, while virtually eliminating waste.


Weld Immune Products


Contrinex www.contrinex.com


SEPTEMBER 2021 | ELECTRONICS TODAY 39


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58