gunrunnerjohn posted:I'm sure it was a cost driven decision, and probably ignorance of how the transformer is used. If you had them on the ABCD side, you'd have to have true circuit isolation for each current measurement channel. Having them on the common U terminal side, there was no extra isolation needed. That just wasn't a workable solution for the way the transformer is used in 99.9% of the installations.
When placing the ammeter on the U common connection bar you get an idea of the total current draw on the transformer. I consider this somewhat useful as you could always turn on each channel one by one, run it separately and see the current draw. Of course an ammeter on each channel is better but how many times do operators watch for current draw?
