Recomend VFD for irrigation system?
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  1. #1
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    Default Recomend VFD for irrigation system?

    Looking to stand up an older irrigation pump here at home.

    575v, 25hp 3600rpm motor running the show.

    Currently set up with a push button start and pretty much no control over it other than On/Off.

    Would like to be able to soft start, dial (or adjust) the frequency to be able to adjust flow output rather than running flat out and simply use or lose the power. Would rather only be paying out for what I actually need, when the number of sprinkler heads varies, rather than running flat out against the max number possible.

    Possibly at some point, a control system with some pressure feedback may be considered, as there seems pretty good odds of a large scale drip irrigation hookup.

    This all sound about par for the course with any VFD of suitable capacity? Getting to a price point where experiments are not super affordable.
    Any brands markedly better than the others, or pretty much all about the same stuff?

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    I would definately look at AutomationDirect. They sell easy to use / program VFD's and just about anything else you may need for your control cabinet. Good pricing, great service and support!

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    Quote Originally Posted by greggv View Post
    I would definately look at AutomationDirect. They sell easy to use / program VFD's and just about anything else you may need for your control cabinet. Good pricing, great service and support!
    They do not seem to have a bunch of equipment rated at 575 Volts. IIRC, 480 Volts is the common 'high voltage' in the States, yes?

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    Quote Originally Posted by trevj View Post

    Would like to be able to soft start, dial (or adjust) the frequency to be able to adjust flow output rather than running flat out and simply use or lose the power. Would rather only be paying out for what I actually need, when the number of sprinkler heads varies, rather than running flat out against the max number possible.
    Go to the pump manufacture's website and download the pump performance curve. You will find that the pump has a narrow operating range were it can run efficiently. There are pumps available that are designed to maintain constant output pressure with varying flow by controlling the rotor RPM. They are used in municipal water systems to replace the old water tower tanks. It is unlikely that your existing pump fits that description.

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    Quote Originally Posted by Robert R View Post
    Go to the pump manufacture's website and download the pump performance curve. You will find that the pump has a narrow operating range were it can run efficiently. There are pumps available that are designed to maintain constant output pressure with varying flow by controlling the rotor RPM. They are used in municipal water systems to replace the old water tower tanks. It is unlikely that your existing pump fits that description.
    I ran across similar comments while searching around.

    <sigh> Yep. More homework to deal with...

    Got till spring, though!

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    Unless you are lifting water from an extremely deep well, this is actually a perfect application for a VFD. 575V is an issue, most of the inexpensive brands don’t do that. I would look at finding an Allen Bradley PowerFlex drive rated for 575V. Good quality, well supported.

    At 25HP you would be in a PowerFlex 523 if you want newest/latest, or a PowerFlex 40 if you buy used*. Either of those will provide you with the basics you need now and they both provide “PID loop control” for when you want to add a pressure transducer later to automate it, eliminating the need for a separate controller if the pump is the only thing to control.

    * When buying a used VFD, always be mindful of how long it has been disconnected from power. If more than a year, you need to take precautions when first applying power in order to avoid potentially damaging the drive beyond repair. If you get one that old or don’t know, you must do a procedure called “capacitor reforming”, which has been described here many times.

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    It pains me to say this because we are a Rockwell Integration partner, but my personal experience with the 52* series (525, 527) drives has been underwhelming. The documentation is hit and miss (encoders described in different places in the manual with lines per rev, counts / rev, pulses per rev, etc. with no rhyme or reason related to quadrature counts in some places and line counts in others) . . . Ughhhh, . . . and the quality substandard as well. If the 523 drive is the same made in China frame with different firmware or hardware configuration, I would pass. I have forbidden my engineers from using these drives unless previously designed in / customer spec after hours and hours of troubleshooting “low cost” drives that had out of box issues.

    When using AB drives, we generally are doing motion or using the drive to give us a safety rated stop . . . anymore we go with 5700 as much as possible or PF 755’s with larger systems and then we common bus with a Siemens Active Line Module. When you spend 2 grand in engineering troubleshooting / dealing with a few “inexpensive” drives . . . it isn’t inexpensive at all and we can’t subject our customers to the same pain and cost that we have experienced with this series of drives.

    A cheaper and easier drive to commission that is well supported would be a CT p/n M400-06500230A . . . 25hp regular duty, 575V, perfect for your pump application. Easy to set up, manuals written in the Queen’s English by engineers with more than a few months out of college under their belt. We aren’t even affiliated with CT but have a hard time not recommending them as they are robust, easy to commission, and can be set up dirt simple or as complex as you want. We have pushed over 2000 CT drives through our shop with far fewer issues than the few dozen 52* drives we have integrated.

    As for pumps under VFD control, we recently shipped a 12 drive, 2400 hp pump control system for a surfing attraction water park in eastern Washington. Siemens all the way . . . controlled wirelessly from an iPad . . . never dreamed you could go surfing in the Cascade mountain range

    World's Largest Stationary Surf Wave Coming to Slidewaters - Lake Chelan News and Information

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    Also if you want some built in pump control versatility . . . Unidrive M400 Pump Solutions | VFD for pumps | Control Techniques


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