Via this Tweet and taken from KYP Bristol, showing the interior with a couple of Westinghouse rotary converters and a Peebles-La Cour motor converter, assuming this picture ties up roughly with this 1908 Institute of Mechanical Engineers' visit to works.
You can see a picture of similar Westinghouse converters to the two at the back in the Wikipedia rotary converter page and a Peebles converter that looks very similar to the one in the foreground on the cover of the Peebles motor converter catalogue in the sidebar of their entry in Grace's Guide. I'm guessing the additions on the ends of the Westinghouse converters were for different voltages? A rotary converter is basically a motor connected to a dynamo, so extra dynamos with different windings would give you different voltage outputs, I suppose, but I know very little about power generation.
GPS Coordinates:
51.44672, -2.61895
Location: Cumberland Basin