Lone Gunman;
The most simplest and "Low Tech" approach to your Control logic is to set up Two (2) Float Switches as a typical "Start / Stop" Motor Control Circuit.
The "Start" Switch would be the Low Water Float Switch.
The "Stop" Switch would be the High Water Float Switch.
These floats would drive the coil of the Motor Starter directly, or indirectly through a Control Relay if needed.
This approach will eliminate the Pump from surging on/off, due to instable high Water levels.
Brief Details of the Control Logic:
The "Low Water" Float Switch is a Normally Closed switch.
When the Water level is at the "Low" set point, this float's contacts will close, and therefore energize the Motor Starter's Coil.
The "Low Water" switch is shunted by the latching contact (as would be found on a typical 3 wire Start / Stop control circuit), so the Coil remains energized as the Water level rises above the "Low" limit point.
This, in turn, opens the contacts on the "Low Water" Float, when the Water rises.
The "High Water" Float Switch is also a Normally Closed Contact switch.
This contact is in series with the "Low Water" contacts + the Latching Contact - as would be normal for the "Stop" Switch on a 3 Wire control circuit.
Until the Water reaches the preset "High Water" level, the float's contacts remain closed.
When the float is activated by the High Water Limit point, the conatcts open, resulting in the Motor Starter's Coil dropping out + opening the Latching Contact; thereby effectively de-energizing the Motor until the Water once again reaches the "Low" level point.
Only Two float switches are required. Each Float only needs one N.C. contact.
If you need a drawing, let me know.
Scott
