Lee, your experience is priceless! A "Farraday Cage" sounds very exotic and a bit scary.
Mark, as far as I'm concerned there's never "too much information". That's how I learn. My first gig after leaving public school industrial arts teaching was the training manager at Fischer and Porter. They were a well-known instrument maker. I was well versed on the other end of the measurement business and 1—5 volts was the standard analog power to do all kinds of measurements from various transducers. I worked there from 1974 through 1980 and witnessed first-hand the transition from discrete panel instruments to computer control. A 1-meg hard drive was available as an option on the computer systems and would set you back $10k. It was 2 feet in diameter and was sealed in an evacuated aluminum dome. Boy... we've come a long way baby! It looks like the measuring stack is before the primary side breakers. The tall thing that's mounted on the side of the transformer I think is the suppression stack.
Yes, in '93 I moved from the substations to the power station to help install a computer control system, I didn't learn much about the VAX computer, but I tested plenty of 1-5 V or 4 to 20 ma transducers depending on how you looked at it. Once all three 900 MW generators were converted and the bugs ironed out, they had a big layoff at the end of '95. I then wound up at the telephone company a year later coming full circle where I had been 20 years earlier. The lord closes some doors and opens others. I'm glad you appreciate the information. I thought you would.