The short-circuit at the Zaporozhye plant in the southeast of the country occurred on Friday, leading to a partial shutdown and electricity shortages in the surrounding region.
"The accident happened in the third block of the Zaporozhye nuclear power plant in the power output section. This is in no way associated with the reactor," Energy Minister Volodymyr Demchyshyn told reporters.
Demchyshyn said tests would be run at the affected block over the next two days and "by Friday it will be working at full strength.
Nuclear power accounts for 44 per cent of Ukraine's power production, according to the UN's International Atomic Energy Agency.
A statement on the power plant's website had said that production unit three had been disconnected from the power network until December 5 and that radiation levels around the plant were "unchanged".
Ukraine was the scene of the worst nuclear accident in history in 1986, when an explosion at the Chernobyl power plant in the north of the country released radiation across large swathes of Europe and the then Soviet Union.