Most watt balances operate in two distinct measurement phases weighing and moving so measurement accuracy could be limited by variations in the environmental and experimental conditions between the two phases. The main novelty of the BIPM watt balance is its implementation of simultaneous weighing and moving measurement phases, in addition to the conventional approach. The great advantage of this simultaneous measurement is to guarantee that the geometric properties of the coil, the coil orientation and the magnetic field, acting in both phases are strictly the same. The simultaneous method hence makes the experiment less sensitive to changes in magnetic field and alignment when compared to a two-phase watt balance. In addition, a comparison of measurements carried out using the conventional and the BIPM simultaneous approach may provide a better understanding of the limiting factors and possibly reveal some unexpected effects unique to each technique.
|The BIPM watt balance|