Water Pump Controls

gar

Senior Member
210726-2401 EDT

paulengr has nicely described the problem, and provided a solution.

I want to continue from there. I believe that it is possible to use only one timer relay.

First, both pressure and well pumps are fairly high power, and therefore their relays ( contractors ) will be slower to actuate ( close a normally open contact ), than a small timer relay.

So I should be able to use a single timer relay.

My circuit would be ----

For the WELL pump motor I have a normally open FLOAT switch that closes when water level is LOW. This contact is paralleled with a normally open contact from the WELL pump contactor ( call this a holding contact ). In series with this set of parallel contacts is a normally closed contact from a high level float. This parallel, series combination goes to the paralleled coils of the WELL PUMP contractor, and TIMER relay.

When low water level occurs the WELL PUMP and TIMER coils are energized, and the HOLDING contact closes and keeps the WELL PUMP running until the HIGH level float switch opens.

The circuit for the PRESSURE pump is very similar. But here we have a LOW PRESSURE normally open contact that closes on low pressure. In series with this LOW PRESSURE contact is a normally closed contact from the TIMER relay in the other circuit. Connected across these two contacts is a normally open contact from the PRESSURE pump contractor. In other words the pressure holding contact. In series with this combination is a normally closed HIGH PRESSURE contact.

Because the timer relay is faster operating than either of the other two pump contactors only one pump contactor will close when both are requested at the same time. Were the two big contactors to actually be fast enough only the well pump would stay on, and the other would only half start.

The software for this site is very poor. It constantly changes my contactor spelling to contractor.

.
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
Why not just use a simple PLC? After all the relay costs and labor you will be locked in to whatever logic you design for. If you go with a PLC you have almost the same cost and total flexibility. You can use floats or you can use liquid level sensors, you can monitor it remotely, log levels, usage, and even add an HMI so you can dynamically change delays, levels, etc... You get infinitely more flexibility and control for almost the same price.

Click Series https://www.automationdirect.com/adc/shopping/catalog/programmable_controllers/click_series_plcs#

P1 Start https://www.automationdirect.com/ad...ivity1000_(stackable_micro_plc)/cpus/p1-start
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
I saw those posts but the OP never responded as to why that was not desirable? I thought I would ask again in case it was skipped over.
 
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