In harsh environments where non-contact speed sensing and control are required, for example to control the slip of AC induction motors, the measurement resolution is usually derived from the number of gear teeth of the target. In many cases the desired resolution is higher than the diameter of the pole wheel and the minimum size of the Module would allow. The new DSI family of speed sensor from Switzerland-based Jaquet Technology Group alleviates this problem by providing speed signals with frequency 16 times higher than the number of teeth of the original pole wheel. Space and weight can then be saved through the dimensioning of smaller pole wheels on the one hand and on the other hand enabling a reliable high resolution output and more finite control system.
Internally the DSI sensors use analog Hall Effect elements, which measure the change of magnetic field that is created by the gear rotation. Sinus and co-sinus signals are generated internally and then processed in real time to produce two streams of rectangular pulses with 90° phase shift. Depending on the sensor model the number of pulses resulting from each gear tooth may be 4 to 16, with the nature of the real time processing ensuring that this occurs from the first tooth sensed. The sensing elements and electronics are potted into a fully sealed housing with the phase shifted signals driven from short circuit proof push-pull outputs. The sensor family works with a pole wheel having Module 1.5, so for a pole wheel with 64 teeth and a diameter of about 100mm there will be up to 1024 impulses per revolution.
Available in various housing sizes, DSI sensors operate over a wide voltage range of 10-30 VDC and have been type tested for demanding applications such as railway traction control. Other applications include pulp and paper industry machinery, hydraulic systems and motor control for printing machines.
Jaquet Technology Group is a global engineering and manufacturing company offering advanced range of solutions for the detection, measurement, diagnosis and management of rotational speed, eg. sensors and protection systems. Its main markets are automotive and truck, power generation, railway, marine, mobile hydraulics and industrial machinery. JAQUET is headquartered in Basel, Switzerland, and has subsidiaries in Belgium, China, Germany, the Netherlands, United Kingdom and United States along with a worldwide distributor and end-user service network. Jaquet Technology Group is ISO 9001 and TS 16949 certified.