Ahhh nostalgia —-
My first introduction to control logic design was designing and building pump control panels with my grandfather. If you happen to find a relay logic panel labeled “C&K Electric”, that was us.
This isn’t one of ours, but it’s pretty similar in design and construction. We really preferred Furnas relays though, and whoever ran the line entrance to this thing needs to be dipped in…. *bwahahahaha* THE PIT!!!
Here’s the basic operation: there are four float switches in the pit.
Switch 1: latch enable. Does nothing when switched on, but if a pump is latched on by its aux contact and it drops from low sewage level, it stops the pump(s). The alternator relay is also triggered at this point; it’s essentially a falling edge triggered gate. This changes up which pump will run next time so they take turns for wear leveling purposes.
Switch 2: start lead pump (as determined by alternator position). This will latch on until switch 1 opens.
Switch 3: Also start lag pump. This occurs when there’s too much flushin’ going on for one pump to handle it alone.
Switch 4: TURD ALERT!!! Condition BROWN! Sewage level is dangerously high; can occur due to pump failures, flooding, or a number of other very nasty things. While switch 4 is active, the red light comes on and an audible alarm sounds. This alarm can be silenced (will auto rearm as soon as the alarm condition clears).
On a side note– I recall the insides of those Diversified Electronics alternators being hilarious. It was like six tiny relays in a potted board and it invoked the obvious question of why not just use a spring loaded pawl mechanism like Furnas does?? Guardian Electric also made a version with a cam and ratchet; it was okay when new but the plastic cam was prone to degrading. Can’t win ’em all I guess.