Whats that? Some kind of rectifyer? I see it has 3 phases into it and some kind of 2-pole output, I assume this is DC given your statement.
It's actually a 12 pulse thyristor driven convertor, powering a 700kW DC motor. It has 2 x 3 phase inputs at 600A each fed from a phase shifting Tx. (One output star, one delta 30 degrees apart thus giving in effect 6 phases) Each phase is then output via the thyrisistors on their pos and neg halves of the cycle thus giving 12 pulses of 'DC' which is fairly smooth compared to, obviously, a 6 pulse.
As you can see there are two 'stacks' each giving DC output. These two outputs are combined in a reactor which is just out of picture to the right and is where I actually got the shock !