Handheld measurement with portable instruments has been a cornerstone of predictive maintenance programs for many years. Portable instruments are often nearly – or equally – as powerful as online systems. They also add the benefit of flexibility, as you can measure without needing to install hardware first.

There are, however, some drawbacks to measurement with handheld instruments. One is the difficulty of performing the measurements with enough consistency in terms of signal quality.

The most common problem is ski slope, which can appear for plenty of reasons. I would like to focus on one. From most of the manufactures spiral cables come as standard. Spiral cables are in many ways user-friendly to work with, but it can give you problems with ski slopes. The reason is that the cable signal quality is affected if the cable is in movement during the measurement. A strong recommendation is the be aware that the cable is not in movement during the measurement. If the problems should persist, talk with your manufacture, and ask if they can supply strength cables instead.

Beyond that, you might be familiar with the other classic reasons that creates ski slopes, such as:

• Throwing the magnet like a lasso instead of placing it gently
• Not having enough settling time
• The sensor and application being measured have a too large temperature difference