Magnetic contact-less speed measurement sensor for steel industries

Speed measurement in steel production is a common task for multiple purposes: line control, strip coiler control, elongation... Nowadays, the most common method for this is the use of encoders in the rolls, but in some lines there is excessive sliding and new methods are required. Laser sensors offer high accuracy (around 0.1%) in the 1000m/minute range, but their cost is quite high (over 10.000 $). In this paper we will explain a complete speed measurement system, using standard components, for steel lines, with a cost lower than 300$, a range up to 800m/minute and accuracy of about 0.4%.