Thanks for offering Darryl, but I have pretty good data on the 120/240VAC single phase motor I am up against. NEC 430 suggests LRC is 188 A, but I am measuring more like 112A during start up. I am thinking that using the VFD for slower ramp up AND as a phase converter from single phase to three phase will help lower inrush significantly.
Jay- with the autotransformer option, I was hoping that the 240V input and 240V output capability of the Victron autotransformer would add some of the benefits of a transformer based inverter to the Sol Ark's transformer-less design. Less about balancing phases and more about adding some inductive kick when the load drops. Am I correct in thinking this is a possible use of this specific device? On Mon, Jan 31, 2022 at 9:43 AM Darryl Thayer <darylsol...@gmail.com> wrote: > 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 >>> >>> _______________________________________________ > 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. 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