You did some work with me about a year ago. I have a small swimming pool electrical project for you if you are interested.
I need to find a way to turn off my 2 pool chemical injectors if the pool pump shuts off. Pool pump could shut off if there is a blockage, someone manually switches it off or power outage.
I pulled the pool pump apart and identified the 3 wires that sends power to the pool pump motor. 2 are hot and 1 is ground. I put a multimeter on the wires and if the pool pump motor was running then 2 wires would read 50v. If the pool pump motor was not running then the 2 wires would be 0v.
Since the injectors used very little power, I tried to use the 2 wires to power both the pool pump motor and injector. Unfortunately there wasn't enough power to power both pool pump motor and injector. Only the injector switch on.
I was thinking, could you somehow use the 50v output as a signal to turn on/off an outlet. My injectors would then be plugged into that outlet.
The chemical injector I am using is the Stenner pump 85MHP17.
The pool pump is the Hayward SP3400VSPVR.
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page 14, figure 5.1.1 is the 3 wires I am talking about
In case you were wondering why I am doing this. One of the chemicals feeders is for Muriatic acid and the other is for Chlorine. The pool pump mixes water to those 2 chemicals and sends it to the pool. If the pump switches off then the 2 acids are mixed together without water and can cause a bad chemical reaction. That is why the city pool inspector is asking to automatically switch off the chemical feeders if the pool pump goes off for whatever reason.