COMPARISON OF DIFFERENT LOAD CHANGERS FOR EMFC-BALANCES

摘要

In order to further improve the metrological properties of weighing systems based on the principle of electromagnetic force compensation (EMFC) as well as quality assurance, it is necessary to determine the parameters relevant for the dynamic operation, such as measurement time and controller behavior. This determination is carried out by loading the balance system and observing the indication. Typically this is done by a load changer using different metrological weights. This method is inevitable if metrological traceability is required. However, the conventional procedure of load changing also entails several disadvantages. The number of possible load changes per unit time is limited and the force characteristic during loading is usually unknown and relatively difficult to reproduce or manipulate. Furthermore the fast and sudden exchange of the weights causes mechanical vibrations and a movement of the surrounding air, both of which act as additional disturbances.