Portable AC current source

Two versions of a portable AC current source with the frequency of the power network are presented. The output current is adjustable in steps from hundreds of mA up to 60 A. Fine current adjustment inside every step is also possible. The phase shift of the output current -60deg, 0deg and +60deg is selectable. Equations for the calculations of the necessary elements to set the desired phase shift have been derived. Some measured results of a constructed sample to be manufactured are also given. The current source is intended to be used for on-site electricity meters accuracy testing without the necessity to bring them into the test laboratory.