KC7Zee is right. That is an old welding machine, circa 1940"s-50"s. We had one similar to it at my plant for the forst few years that I began to work there.

Some of these guys are right, they are reactors on the "c" Phase of the three phase generation bank . The "C" with a o and a line through it stands for "C" phase.

As Vinton and EE have already mentioned above , it is a synchroscope to "synch" the main generator to the grid.Most modern power plants run at 3600 rpm at the turbine -generator, with a two pole generator producing three phase power.

Looks like a bank of batteries for dc backup in the power plant. Most plants have a dc backup for lighting should they lose power. Also, dc power is used for UPS(Uninterruptable power supplies) to run some of the controls for the plant itself. The picture of a frame or two ago of the Mg sets might be the dc charging sets for the battery room in this picture. I don't believe that they are ac to dc frequency changers from the main generator.

Cs is right , those are stay bolts for the doors on the suface condenser , under the turbine-generator unit. I have worked in a power plant for the last 28 years and hope to be here a few more years before retiring. You are probably looking at the rear of the condenser, and the shot that you saw with the man in it was the front side of this unit.