Stressful Load Cell Applications
Traditionally a strain gauge
load cell has a resistance foil attached to an elastic element which when a load is applied changes, this change can then be measured and converted into a digital output and is used to ascertain the weight or mass - as most of us will stay on planet earth the weight will always equal the mass so for the purposes of this article we will use the term weight. The problems with this method of measuring mass are greatly enhanced when placed in a stressful situation where loads, shocks, vibrations and physical distances all combine to cause problems. A sudden shock to a standard cell can break the weighing device completely or more commonly affect its accuracy. If our home scales were to inaccurately report we had put on an extra pound very little effect would be caused but if a
load cell used in a fast moving production process were to continually report inaccurate measurements, even slight, these combine to a much bigger problem.
By using a capacitive sensor instead of the resistance foil we immediately reduce the exposure to large shocks or overloading. As the device is non-contact it can handle such effects and still retain its accuracy. Moving away from an analogue output to digital also means that the device is simpler to install, and simpler also means cheaper. It is also less expensive to maintain and as only a single wire is required it is much simpler to seal water tight enabling business to position the
load cell exactly where they want it and at the same time have the read-out device also in their desaired location without having to compromise. This also enables another unique attribute, you can change the length of the cable without having to recalibrate the device, in fact many types of non-contact
load cells allow you to entirely replace the cable on site.
