The power has been switched off at Alcoa's aluminium smelter near Geelong, marking the end of 51 years of continuous operation.

The final pot line was switched off with the sound of beeping on Thursday.

The closure sees 500 workers out of a job.

Smelter manager Warren Sharp said staff have supported each other since Alcoa announced the closure in February.

"People have had all those mixed emotions over the past five months. The team here has been absolutely tremendous," he said.

He said there was a lot of pride in what the company has achieved since it started at Point Henry in 1963.

"We've built three pot lines, we've had tremendous support from the community who we've had a great relationship with, we've made 7 million tonnes of aluminium over the journey," he said.

"That makes us very proud, and of course, very sad today as well."

Another 300 workers will lose their jobs when Alcoa's rolling mill closes at the end of the year.

Take a look back through some old and new pictures of the plant to see its transformation over five decades.

An engineer drawing in an office at Aloca, Point Henry, 1967. ( State Library of Victoria: Wolfgang Sievers )

Rolls of sheet aluminium at the Alcoa fabrication plant 1971. ( State Library of Victoria: Wolfgang Sievers )

Operator's console, Aluminium rolling cold mills, Alcoa aluminium fabrication plant, Point Henry, Victoria (date unknown). ( State Library of Victoria: Wolfgang Sievers )

Worker operating the cutting apparatus on the aluminium sheet slitting line, Alcoa aluminium fabrication plant, Point Henry, Victoria, in 1971. ( State Library of Victoria: Wolfgang Sievers )

Display of aluminium extrusion profiles manufactured at Alcoa aluminium fabrication plant, Point Henry, Victoria ( State Library of Victoria: Wolfgang Sievers )

The ground-level windows help reduce ventilation in the Alcoa smelter July 31, 2014. ( ABC News: Margaret Paul )

Alcoa's newest pot line dates back to the 1970s. This is final line that was operating and was switched off on July 31, 2014. ( ABC News: Margaret Paul )