Unit 3’s auxiliary power transformers and excitation transformer were also energised in normal operating configuration.
Enec said the milestones were important steps in the continued testing and commissioning of the South Korea-supplied APR1400 plant.
The milestones were announced approximately one year after the completion of similar work on Unit 2, and two years after the completion of the same work on Unit 1. Enec said this demonsrates the benefits of building four identical units at the same time.
Enec said the testing and commissioning teams will now begin preparing for the start of hot functional testing at Unit 3, a process that will also accommodate lessons learned from the construction of Units 1 and 2.
Hot functional testing takes place over a number of weeks and consists of almost 200 individual and integrated tests performed on major systems to check their performance under normal operational conditions, without nuclear fuel assemblies in the reactor vessel.
The construction of the four-unit Barakah nuclear station is progressing steadily, Enec said. Unit 2 stands at 95% complete, Unit 3 is more than 91% complete and Unit 4 is more than 82% complete. The overall construction completion percentage is more than 93%.
The construction of Unit 1 has been completed and it is currently undergoing commissioning and testing before regulatory review and receipt of an operating licence from the Federal Authority for Nuclear Regulation.