I think we need a refresher; some of the above information is incomplete.
Floats on rods? How quaint. The most common arrangement uses simple floats on cords, tied off to a pipe.
If there's but one pump, and one float, the float has a 'piggyback' plug, and your delay between 'on' and 'off' is built into the float.
The delay prevents short-cycling of the pump. Typically, the float will be pointing noticeably 'up' before the contacts inside close, and pointing noticeable 'down' before the contacts open again. This gives you perhaps a 4" difference between the 'on' and 'off' water levels.
For duplex pumps, you have a single circuit supplying the control panel. The control panel, in turn, feeds the pumps.
Your lowest float doesn't seem, at first glance, to do anything. Yet, if it doesn't close, neither pump will work. It serves to shut everything 'off' after the sump has been pumped down.
The next float turns on the first pump. An alternating relay in the panel will make the pumps take turns being 'lead' pump.
The third float - usually also the top float- will turn on the second pump and sound the alarm.
If there's a fourth float, it's the top float, and it only sounds the alarm. In this set-up, the third float only operates the second pump.
Now ... commercial plug time ... I've seen a variety of pump panels. One place seemed good, until I called them for a replacement part, and only silliness followed.
A surprising number of the panels I've seen, under various names, have come from SJE-Rhombus. You can buy direct, and their customer service is top-notch.
