Hi i have a single phase motor at a old install that i replaced about 8 years ago. Would it help if i made some starting load surge measurments?
On Fri, Jan 28, 2022, 11:52 PM Darryl Thayer <darylsol...@gmail.com> wrote: > Hi Chris, In the past, I was able to start a 5 hp pump motor using a VFD. > , I can not remember the make, of the VFD but I think it was an ABB 7.5 or > 10 HP connected to a single-phase motor. I started it on two Outback 3548s > (or maybe 3024s). Now for the tricky part, I have done this several times > over the years so I keep confusing the systems. you must power the VFD > before starting the motor to charge the capacitors as the VFD will also > have a loading surge.( one time on maybe 10 HP I did a homemade resistor) > The VFD has a large capacitance and will have a surge. Most water pumps do > not have a high zero-speed torque requirement, meaning low inertia, so you > can use a slower ramp to speed. watch your speed as the VFD can Overspeed > the motor increasing the load. The advantage of the VFD is it can run at a > lower speed reducing the load on the inverter. I also think an Auto > Transformer will balance the load between the inverters, but may not be > necessary. > Also be aware that starting surge is on the battery also, If your motor > has aGH motor it can have a 4 to7 times the running loads on starting. NEC > 430,7 I think. This can be well over 100 amps. The inverter will sag in > voltage during startup but they may draw 400 or 500 amps from the battery. > If my memory is correct the 10 HP VFD has the possibility of adding an > extra capacitor which reduces AC starting draw. > Sorry, this was so long, it was more than 20 years ago for me. > > > On Fri, Jan 28, 2022 at 10:46 AM Chris Sparadeo <sparadeo.ch...@gmail.com> > wrote: > >> Hi all, >> >> I currently have an off-grid client that has a 120/240VAC 7.5 HP - 40A >> FLC single phase pool pump. Locked rotor current is around 110 A. I had >> initially (and naively) thought that two Sol Ark 12k units would be able to >> handle this load. Due to the lack of a transformer, the unit's just can't >> output the required inductive startup inrush. Now getting clarification >> from Sol Ark that max inductive HP output is 2.5 HP per unit. We had >> installed an amply sized SR35 soft starter, with no avail. The 20 kW >> generator can start the motor, but it is noticeably shaken with the >> intense load drop. >> >> I am toying with the idea of installing a VFD and upgrading the pool pump >> to a three phase motor. Would make for a much smoother ramp and self start. >> The client is a bit hesitant to upgrade and would like to continue using >> their clunky, non-self starting single phase motor. >> >> My other thought was to implement an autotransformer to add some copper >> to the equation and help the Sol Ark's get the job done. Has anyone had any >> experience with the Victron 100A autotransformer for both 120/240 input and >> output? >> >> Any suggestions or relative experience would be greatly appreciated! >> >> -Kindly, >> >> -Chris >> >> -- >> >> *Chris Sparadeo * >> >> *NABCEP Certified PV Installation Professional **® **# 042919-015652* >> >> *NABCEP Certified PV System Inspector **®** # 052920-015652 * >> >> *State of Vermont Journeyman Electrician # EJ-07619* >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org >> >>
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