Hello,
I am only a DiYer and not qualified engineer but I'm hoping to get some help to resolve a problem that's really bugging me.

I have a rural property that benefits from a bore hole for water service. For many years the 'manual' circuit has been satisfactory. Power runs from an mcb through to a contactor. A three way switch allows isolation, manual or automatic filling of a water tank according to the position of it's float switch. See BoreHoleWiring.pdf attached.

I now wish to incorporate a Shelly controller into the circuit to allow for remote activation. MainWaterSchematic.pdf is the schematic.
The problem that I am suffering from is that when the float switch energizes for the first time, the contactor sends the Live to the Shelly SW terminal and the pump is activated as expected BUT when the water level reaches it's high point, the contactor remains on. (As if the contactor is stuck on but is not the case as I have tested and it switches on and off as desired). Also the float switch is proving good. It was one of the first items I replaced suspecting it as defective.
No mcb has 'tripped'. no wires shorted out, no bangs or fires.
Clearly there is something that is beyond my comprehension and I'm hoping dear reader that you can offer some help.

 

Is the pump three phase 220V? Is the L on the Shelly the same as one of the phases on the top circuit breaker?
I have the float switch not connected to "power" or Contactor" but connected directly to the Shelly L to Switch. I don't see the need for the small contactor.

 

Hi Ron,
Thanks for the quick comeback. Yes 3 phase 230v system for the pump. I have 3 phase coming in from the meter into the DP. My other circuits are spread over the three lines for balance. The L to power the Shelly comes from one of the lines but not sure which one. The small contactor below the (now) 2 way switch is to produce a Live to the Shelly SW terminal. When the Shelly detects a Live on SW it energizes the O terminal and thereby gives the main contactor coil its Positive.

 

I do have some Shellys but not many. I use something different.
I am concerned that we don't understand how the Shelly works. I would put a switch on the Shelly Switch to L pins and a light bulb or ohm meter on the I/0 pins and make certain how it works. What I have, there are several different modes that work different. (on=on, off=off) or (on=off, off=on) or (on to off transition = off, off to on transistor = on) or ? I don't remember. Mine acts different (level) verses (transition).

If I wanted to force the pump on, I would put the Shelly at location 1.
If I wanted to stop the pump under all conditions, I would put it at location 2. (Cut the wires.) Open=off
If I wanted to stop the pump only when it is in Auto mode I would put the Shelly at 3. (Cut the wires.) Open=off

Do you want to see if the main contractor is on or off using the Shelly?
Do you want to see of the Flout is up or down using the Shelly?