A coil damage led to disconnection of the house load transformer and unit transformer breakers.
Following this, Zaporizhzhya NPP disconnected the reactor from the integrated power system.
However, no radioactive consequences were reported and work is underway on restoring house load power supply.
The unit 3 is expected to be reconnected to the grid on 5 December 2014.
The company is currently operating four nuclear power stations in Ukraine.
Ukraine Energy and Coal Industry Minister Volodymyr Demchyshyn said: "Actually, there is no threat at the Zaporizhia nuclear power plant.
"There was an electrical short circuit in the system of energy delivery late last week, thus, only one unit, unit ?3, is out of order at the nuclear power plant. There is no threat to the reactor. This is technical damage which is being eliminated."
Although the reactor disconnection from the grid did not cause significant damage, the capacity of power supply has been affected, Demchyshyn said.
Located in central part of Ukraine near the city of Enerhodar, on the banks of the Kakhovka Reservoir on the Dnieper River, the power plant comprises six VVER-1000 pressurized light water nuclear reactors, each generating 1,000MW.
The plant, which is considered as the largest nuclear power plant in Europe and the fifth largest in the world, produces more than a fifth of total electricity generated in the country.
Image: The Zaporizhia nuclear power station located in Enerhodar, Ukraine. Photo: courtesy of Ralf1969.
