| 摘要 |
Disclosed is a power supply for measuring the line impedance of an underground cable, which includes an input terminal section having a plurality of input terminals, a plurality of autotransformers, a transformer adjustment tap, a plurality of 3rd-harmonics cancellation transformers, and an output terminal section having a plurality of output terminals. The autotransformers are connected respectively to the input terminals. The transformer adjustment tap is connected to all of the autotransformers. The 3rd-harmonics cancellation transformers are connected respectively to the autotransformers. The output terminals are connected respectively to the 3rd-harmonics cancellation transformers. The autotransformers are simultaneously controlled by the transformer adjustment tap so as to uniformly boost the powers supplied respectively to the autotransformers, and 3rd-harmonics of the powers are cancelled in the 3rd-harmonics cancellation transformers to remove noise, so that the powers are stably applied respectively to the phases of the underground cable.
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