What are the limitations of using a capacitive level measuring system?
Capacitive level measuring systems work satisfactorily where the electrical characteristics of the service material do not vary with time. As observed from the above formula, once the probe is installed the distance between the electrodes and the area of the electrode remain stable. What can vary with time is the dielectric constant of the material. Dielectric changes can occur due to changing moisture content, changing geometric configuration in the case of lumpy material, temperature variations in certain substances prone to change with temperature, blended substances where the ratio of ingredients determining the mix, change. It can also change due to incorrect probe insulation that varies with temperature or has a tendency to absorb moisture. It can vary as a result of build up of static charge on the probe or due to floating particles carrying a static charge in the vicinity of the probe. Other conditions responsible for a change in the probe capacitance with time could be due to
