Homemade Variable Speed Pump

[bobodaclown]

OK here's my question.
I purchase a Variable Speed controller such as: SMV AC Vector Drive - ESV751N02YXB
It cost about $200. ESV751N01SXB ESV751N01SXB 751N0: 1 HP (.75 kW) 1SX: 120-240 Volt, Single Phase $218.90
http://www.wolfautomation.com/produ...rup-to-30hp-single3-phasebrac-tech-smvector-b
http://www.wolfautomation.com/assets/15/smvector.pdf


Pick up a 3 phase motor: 1HP 3 phase square mount another $200
http://www.grainger.com/Grainger/AO-SMITH-Pool-Pump-Motor-4YY44?Pid=search

So for $400....
Mount it to a 1HP Intelli flow body or use as a replacement for a 1 HP. Then you have a Variable Speed Pump

Also see this video:
http://www.vegetablegarden.tv/video/xHY ... h-POT.html

Any one willing to chime in?

Thanks,
Bob
(added links for controller)

 

[Brentr]

I would be interested in your findings too.

 

[JasonLion]

That can work. The only issue is how efficient the variable speed controller is. High electrical efficiency at low speeds is not always a primary design criteria for the controllers. Of course, even an inefficient variable speed controller will be way better than a single speed pump, but some are better than others. And none of them can match the efficiency of the IntelliFlo or EcoStar pumps, which use motor designs with higher inherent efficiency than a standard three phase motor.

If you have an existing pump with a bad motor and are into DIY projects, this can be a great idea. But if you have a working pump or don't have any pump at all, this approach is unlikely to be worth doing in economic terms. Unless your electric rates are very high, replacing a working pump is unlikely to ever pay back the extra investment, and if you are getting a new pump from scratch you will almost always be better off either getting a two speed pump if your electric rates are low or an IntelliFlo/EcoStar if your electric rates are high.

By the by, there are also variable frequency drive controllers that will work with some single phase motors. If you happen to have the correct kind of motor on hand that can be a better approach than replacing the motor to go the three phase route.

 

[JamesW]

Do you have three-phase power available? If you don't have it, it might be possible to get, but there might be a charge from the power company to supply it.

Also, you might need additional power equipment if what you're trying to do induces disruptive harmonics into the power lines.

 

[JasonLion]

Variable frequency vector controllers are available with single phase inputs and three phase outputs, so there is no need to get three phase power from the power company. The modern ones are also designed to avoid or at least minimize any disruptive harmonics, so that shouldn't be an issue.

 

[bobodaclown]

Variable frequency vector controllers are available with single phase inputs and three phase outputs, so there is no need to get three phase power from the power company. The modern ones are also designed to avoid or minimize any disruptive harmonics, so that shouldn't be an issue.

That was the Variable Frequency Controller that I linked to. It uses 120V single phase they also offer 240V controller also.
Yeah, definitely a DIY project, but for around $500 a VSP vice a dual speed seems very cool.

I believe Pentair uses there 3HP impeller on their VSPs. I wonder what the actual motor rating is?

 

[mas985]

You need to make sure that the motor is inverter duty otherwise it probably won't last very long. Both the insulation and bearings have to be more robust to handle the harmonics generated by a VFD. Also, this spec "Thermal Protection None" is a problem. I would always have thermal protection on a motor.

Also, it is a good idea to use a matched sheilded cable to minimize interference to other electrical equipment plus keep the reflected waves from damaging the VFD.

Next, a Nema 1 enclosure is not rated for outdoors so you may need another enclosure to protect it.

At one time, I had looked into doing this but quickly found out that to do it right, I was going to be spending close to what a VS cost anyway.