Hi Chris, I’m not enough of an EE to know that answer. But my guess is it isn’t going to be enough to make much of a difference, still a massive hit on the inverters
Given the cost of the transformers with install vs the correct motor with VFD drive. I’d go with new motor/VFD and you know for sure it’s going to work. Jay > On Jan 31, 2022, at 9:50 AM, Chris Sparadeo <sparadeo.ch...@gmail.com> wrote: > > > 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. 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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