OT Pool control system

I plan on doing a home project for my above ground pool.

I plan on using a single to three vfd to run the pump motor at different frequencies and times to allow the pool to stay clean but not cost $40-60 to operate full time.

I am also planning on adding a pressure switch to the filter housing to let me know if the strainer is clogged prevent burning a pump up.

I would use a 1100 plc and a cmore micro touchscreen.

I will contol the deck lighting and Secondary magnetic door lock(i have a young child that likes to explore)

The system will alarm in the house and garage if the gate has been opened or left opened for more then a small length of time.

Is there a sensor avail that will detect ph? This will be used to judge when chemicals need to be added.

Is there any suggestions about this type of system.

Pool

what do you want a designer? This I can do. I have a plc running a saltwater fish tank, A plc running my heat pump. that would be easy. I also use c-more HMI's at work. c-more micro to be specfic to run my Air controlling project.

I am not needing a designer. I was bored and started thinking about what project i can do. This will be my first home plc project but i program plc's and touchscreens at work. Do you know of anything else i would be able to add to the project the i might have left out.

What all are you controlling on your fishtank?

Do you know of any ph sensors i will able to use?

We get our Ph sensors from Omega..4-20ma...but dont forget for a pool you will also need the clorine/bromine sensor plus an alkaline sensor...

A pool may be different from a well designed saltwater tank as PH does not need to be monitered but A pool, Chlorine and acid or ph should. and that was not my design since ph is a constant 8.2 no matter of refills.

you also asked why do I need a plc to control a fish tank? Although the Water systems are so well built that after 2 years of monitering, all systems needed minor maintenance. I Put a PLC to automate water change and several alarms after a leak.

I currently have a plc controlling my pool. Heres a couple of ideas you might like to consider
1. Use the plc real time clock to set the filter run time according to the month
2. I use a simple pushbutton panel to control all the pumps and lights (one button for each pump) pushing the button toggles the current state
3. Run some yard lighting according to time
4. Use the plc to control the solar heating. The control unit that originally came with the solar system has to be the most ineffiecent (just plain dumb) program ever.
5. In future I plan to write a vb application (I know I could use a scada system) to allow monitoring and control (adjustment of times, etc) and logging of chemical usage.

Anyway good luck on your project

2004sk4 said:

...Do you know of anything else i would be able to add to the project the i might have left out...

Click to expand...

Times do change. Perhaps it's over for me, perhaps I'm from another era, but there was a time when all would have tought about beer keg temperature control... Hey! What good would a pool be with no MGD to celebrate?

If this is so-worth while doing, could you post your calculations?

Would you mind posting your calculations of how you would think that by using a 3 phase motor, a single phase fed - 3P output drive, and changing the frequency during the day would save money?

For example, I am using a 1.0 HP pump, 8 hours of the day in order to achieve MINIMUM circulation for my pool of 21' diameter.

Distribution charge (per kWh) $0.0178
Cost of power (per kWh) $0.081*
Total (per kWh) $0.0988

Running at a constant speed, the basic calculations would be;

Average appliance wattage: 1500W Average hours of daily use: 8Hrs

Average daily kWh used: 12.00 Kwh Average daily cost: $1.19
Average monthly cost: $36.04 Average annual cost: $432.74

This is received from the website
http://www.hydroonebrampton.com/appliancechart.html

Is it really worth the change? I would love to see some real life calculations.

SNK said:

Would you mind posting your calculations of how you would think that by using a 3 phase motor, a single phase fed - 3P output drive, and changing the frequency during the day would save money?

For example, I am using a 1.0 HP pump, 8 hours of the day in order to achieve MINIMUM circulation for my pool of 21' diameter.

Distribution charge (per kWh) $0.0178
Cost of power (per kWh) $0.081*
Total (per kWh) $0.0988

Running at a constant speed, the basic calculations would be;

Average appliance wattage: 1500W Average hours of daily use: 8Hrs

Average daily kWh used: 12.00 Kwh Average daily cost: $1.19
Average monthly cost: $36.04 Average annual cost: $432.74

This is received from the website
http://www.hydroonebrampton.com/appliancechart.html

Is it really worth the change? I would love to see some real life calculations.

Click to expand...

I think 2004sk4 needs to give you his kWh cost to determine that. In NW Ohio some rates are $0.13 at times. BUT, I would be more concerned about the motor; minimum speed for cooling and windings rated for VFD that sort of thing. If the motor isn't VFD rated you could fry it and you would add the replacement cost. The speed will depend on the pump curve. Another way to save (without a VFD) would be to throttle the flow of the existing pump. Some piping and a solenoid valve or two would do. Just measure the motor amps and figure potential savings.
For a side project add a solar collector with temperature monitoring to keep the pool at a more constant temperature.

Yeah, I have a solar recirc system, but it is recirculated via a manual hand operated valve. If it is sunny, recirc to the solar system, if it is dark, MAKE sure that the valve is in the NON-SOLAR-RECIRC loop. It requires constant supervision.
If the pump isn't running, it really doesnt matter. If the pump is running, and it is cool and dark outside, the solar system actually works like a cooling coil. It will cool down your pool.


In order to automate this valve, you would need one heck of a system, an air system, or a control solenoid, and I have priced this stuff. Very expensive.

My point is, is it all really worth it?

For a project in order to keep yourself occupied, well OK. It will cost you money though. Large money. So much that I just wonder if it is all worthwhile for the benefit.

suggestion:

Use a differential pressure (DP) switch across the filter to signal when the filter clogs and needs cleaning/backwashing.

Knowing this condition, you could automate a backwash sequence to clean the filter medium.

I suspect that any commercial filter manufacturer could tell you what DP indicates a 'needs cleaning' condition.

When looking for DP switches, the switch needs to be able to handle the working pressure (pump pressure) on the high side.

Dan