A hybrid AC and DC power source for the tests of an HTS tapes

The structure and the results of measurements of a hybrid supplying system for the tests of an HTS tapes carrying the high amplitude AC current with DC offset is described in the paper. The system is dedicated to an examination of the second generation (2G) superconducting tapes operating under dynamic conditions (the transition between superconducting and resistive state). The tapes are bifilarly arranged and immersed in LN2. The system for the tests consists of the high current transformer (up to 500 A_RMS) and the controlled DC supply (up to 200 A). The load current in the superconducting tape is a sum of the current of the transformer (sinusoidal shape) and the DC supply (constant value). The frequency of AC component is a grid frequency (50 Hz). The structure of the system is described in the paper. Some details of the transformer geometry and parameters are presented. The results of measurements are used to estimate the power distribution in the system. Operation at different regimes (different DC to AC amplitude ratio) is analyzed. Some representative results of measurements are presented and discussed.