I agree with Mitch. They are part actuator for the main steam valves.

The loop is there for expansion

They are the end windings of the generator

No need to wonder -- The exciter provides DC power to the field coils on the rotor of the generator to create the magnetic field. When the rotor is turned by the turbine the magnetic field spins and passes through the coils (armature) of the generator to generate electricity.

It is an electrical insulator probably to keep the 250 V rail away from what ever structure was supporitng it

Those tubes are too small to be those of a boiler. They are condenser tubes. What you are seeing here is the waterbox where the cooling water enters or leaves. The steam to be cooled would be on the other side of those tubes and tube sheets.

PCB's are Poly Chlorinated Biphneyls which are a class of chemicals that were added to electrical insulating fluids (and semi solids) to render them less flammable. They are toxic and when they burn (note I said less flammable) they would turn into dioxin which is even more toxic than PCB. They went by several trade names such as Askarel, Arochlor and Chlorhextol.

It appears that this is the same equipment as in the picture 'Rusted Ventricles' (Motts?). If it is thenthese are the motor drives for a set of draft fans (fans that move air through the boiler). There are a few types of fans FD which force air into the boiler, ID that remove combustin gasses from the boiler and Gas Recirc that move the air around in the boiler.

The rails of the battery rack have a protective cover on them to keep the acid off the rails. Its the covers that are deforming.

These are the phase markings for a three phase AC system. Most U.S. utilities label the phases A, B, C. This is how they keep track of what wiring to connect together. If the phasing is not followed through, a dangerous short circuit can be created. These picures depict what is known as cell type construction where the compartments containing the electrical conductors are part of the building.

With the dial marked as Motts describes it is a frequency meter. The US and Canadian power systems are operated at 60 Hz or cycles per second. A synchroscope is marked 'slow' and 'fast' and sometimes with the number of degrees out of phase. 0 degrees (pointer straight up) Is in sycnc and 180 (pointer straight down) is as far out of synch as you can get. Vinton is correct -- I have seen AC generating units where there has been a synchronizing accident. The damage can be anything from mechaincal damage to the turbine shaft & blades, to the generator, its circuit brekaer and transformer. Most modern plants have controls to do the synch and help prevent a synchroizing accident from occuring. I once added these controls to a generator about the same vintage as the one in this gallery.

A transformer with the core & coils (insides) removed

This is the condenser. CS is correct.

Fire tube boilers each with two burners. The water to be heated is insde the tank and the fire / hot combustion gasses run through the tubes to the stack.

These are a motor generator sets. An AC motor spins a generator. The output of the generator could be AC or DC. If it is DC (which it probably is based on the appearacne of the brush riggings and commuator) the output could have been used to charge the control batteries or provide field current to the main generators. This was very common in power plants from this time period. There is also a possibility that this could be an ampllidyne (also part of the main generaator field circuit) althouhg this plant may be a bit too old for that.

EE has worked as an Electrical Engineer in a number of generating plants (fossil & nuclear). I have also worked in steam heat and chilled water (air condtioning) plants (that serve portions of cities) as well as electrical substations. There are panels that are more monster than that, but modern plants have a few computer screens that replace all of the massive boards. About the only thing that is a wired control today is the emergency stop pushbutton.

This is a boiler plant control panel. The guages (air flow, fuiel flow, steam pressure, etc...) and indicators are on the 'vertical' portion and the controls are on the 'horizontal' portion.

The panel in the front is the bench board where the control switches are (the operator initiated the control actions from here). The panel in the background is the vertical board which had the meters & other indicators on it where the operator could monitor the results of the actions (most of the indicators have been removed the shadow lines where they were can be seen) . Both are 1920's vintage and are probably made from slate.

This is a heating radiator. There must have been a reactor nearby. In a power station, the reactors (electrical) were typically to limit fault current.

This is a thermometer that was proabbly connected to a set of thermocouples. The switch would let the operator read either the throttle temperature (where the steam enters the turbine) ot the 5th stage temperature (at the 5th set of blades in the turbine) where they may have extracted steam for feedwater heating.