Kilowatt Power Posted November 10, 2019 Share Posted November 10, 2019 Greetings, Can 3 * 5kW Axpert inverters in 3-phase parallel configuration (total 15kW) start a 9.3kW/12.5HP 415VAC 3-phase submersible well pump? I've not gotten to measure the pump's inrush current but it's a typical multistage centrifugal pump with an asynchronous squirrel cage motor manufactured by Silver Pumps & Motors (India). NB: The housing complex cannot increase installed capacity of the water storage tank hence the need for at least 2 hours power backup in lieu of a diesel standby generator set. Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 10, 2019 Author Share Posted November 10, 2019 I've been investigating a second option of directly coupling a 576VDC lead acid battery bank (48 * 12VDC * 65Ah batteries in series) to the DC bus of a 15kW Variable Frequency Drive but I cannot find a constant current regulator/battery charger operating near 600VDC. Quote Link to comment Share on other sites More sharing options...
Coulomb Posted November 12, 2019 Share Posted November 12, 2019 On 2019/11/11 at 1:16 AM, Kilowatt Power said: Can 3 * 5kW Axpert inverters in 3-phase parallel configuration (total 15kW) start a 9.3kW/12.5HP 415VAC 3-phase submersible well pump? I wouldn't think so, without some sort of soft start device or VFD set up to do a soft start. Kilowatt Power 1 Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 13, 2019 Author Share Posted November 13, 2019 Quote I wouldn't think so, without some sort of soft start device or VFD set up to do a soft start. I agree with you. I got to measure the inrush current using a UNI-T UT216C clamp meter and the pump is gobbling 77.6A at startup then roughly 21A during normal running. Mind you this is at 415VAC. The starting power requirements are simply beyond what 3 * 5kW Axperts in parallel configuration could offer. i.e. 32.2kW vs 30kW peak power. Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 13, 2019 Share Posted November 13, 2019 Mmm. You would need 415x1.73*77.6, or 55 KVA... You only need a DC VFD, no inverter is needed Kilowatt Power 1 Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 14, 2019 Author Share Posted November 14, 2019 Quote Mmm. You would need 415x1.73*77.6, or 55 KVA... Thanks for the kW = 1.732*V*I*PF/1000 correction On 2019/11/14 at 12:59 AM, Javi Martínez said: You only need a DC VFD, no inverter is needed Any pointers to a suitable battery operated DC VFD in the market? Quote Link to comment Share on other sites More sharing options...
Richard Mackay Posted November 15, 2019 Share Posted November 15, 2019 4 hours ago, Kilowatt Power said: Any pointers to a suitable battery operated DC VFD in the market? Any VSD will manage the slow start (and lower start up current) These devices generate their own DC bus from AC power being fed to the unit so no need for the external batteries. Quote Link to comment Share on other sites More sharing options...
Richard Mackay Posted November 15, 2019 Share Posted November 15, 2019 On 2019/11/13 at 9:58 PM, Kilowatt Power said: I agree with you. I got to measure the inrush current using a UNI-T UT216C clamp meter and the pump is gobbling 77.6A at startup then roughly 21A during normal running. Mind you this is at 415VAC. The starting power requirements are simply beyond what 3 * 5kW Axperts in parallel configuration could offer. i.e. 32.2kW vs 30kW peak power. Do you have the Axpert inverters already? If so what I would do is to start the pump with regular power and then simulate a power outage and see if the inverters will keep the pump running. If so we can then address the startup current peak.. Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 15, 2019 Author Share Posted November 15, 2019 37 minutes ago, Richard Mackay said: Do you have the Axpert inverters already? Not yet acquired. I'm glad that I sought your views before embarking in that direction. Quote Link to comment Share on other sites More sharing options...
Richard Mackay Posted November 15, 2019 Share Posted November 15, 2019 Any reason you are looking at Axpert?? Quote Link to comment Share on other sites More sharing options...
PJJ Posted November 15, 2019 Share Posted November 15, 2019 Just now, Richard Mackay said: Any reason you are looking at Axpert?? Well its the cheapest way of getting to 15KW without going to the really dumpster fire section of the inverter world. ___ and Kilowatt Power 1 1 Quote Link to comment Share on other sites More sharing options...
___ Posted November 15, 2019 Share Posted November 15, 2019 32 minutes ago, PJJ said: Well its the cheapest way of getting to 15KW without going to the really dumpster fire section of the inverter world. Man! What an absolutely brilliant way to put it I need fresh coffee... this cup has some mucus drifting in it now... PJJ 1 Quote Link to comment Share on other sites More sharing options...
Richard Mackay Posted November 15, 2019 Share Posted November 15, 2019 1 hour ago, PJJ said: Well its the cheapest way of getting to 15KW without going to the really dumpster fire section of the inverter world. Is that synchronised 3 phase (i.e each phase 120 deg with respect to each other) Quote Link to comment Share on other sites More sharing options...
PJJ Posted November 15, 2019 Share Posted November 15, 2019 37 minutes ago, Richard Mackay said: Is that synchronised 3 phase (i.e each phase 120 deg with respect to each other) Yup, you do need 3 inverters tough, one for each phase, in Program 28 on the Axpert you can assign each inverter to its respective phase. You will also get a fault code 82 in event of a synchronization loss (Or well atleast that's what I can gather from the Axpert manual) Kilowatt Power, ___ and Richard Mackay 3 Quote Link to comment Share on other sites More sharing options...
Richard Mackay Posted November 15, 2019 Share Posted November 15, 2019 1 hour ago, PJJ said: Yup, you do need 3 inverters tough, one for each phase, in Program 28 on the Axpert you can assign each inverter to its respective phase. You will also get a fault code 82 in event of a synchronization loss (Or well atleast that's what I can gather from the Axpert manual) Has anyone implemented this config in the real world and able to provide some feedback?? Quote Link to comment Share on other sites More sharing options...
PJJ Posted November 15, 2019 Share Posted November 15, 2019 23 minutes ago, Richard Mackay said: Has anyone implemented this config in the real world and able to provide some feedback?? I have never done it, but in theory it should work, but lets call the resident Axpert expert @Youda Quote Link to comment Share on other sites More sharing options...
Youda Posted November 15, 2019 Share Posted November 15, 2019 A friend of mine is using this setup to power his workshop, including all the 3-phase machines and tools. The setup produces nice and clean 3-phase power with the correct phase-shift between the phases. The grid is not needed for the start, you can use this even when you're completely offgrid. Works with a 1-phase loads too, it's capable of supporting assymetrical phase load. BTW: In my own setup, I'm using a different gear, three InfiniSolar inverters working in parallel in a 1-phase 15KW system. Richard Mackay and Kilowatt Power 2 Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 15, 2019 Share Posted November 15, 2019 (edited) As I said before, you only need a solar VFD and 15 Kwp of solar pannels. No batteries, no charger, no inverters... https://www.zuendo.com/ls-solar-trifasico-380-v/2863-variador-de-frecuencia-solar-trifasico-11-kw-ls.html Edited November 15, 2019 by Javi Martínez Youda 1 Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 15, 2019 Share Posted November 15, 2019 (edited) 23 hours ago, Kilowatt Power said: Thanks for the kW = 1.732*V*I*PF/1000 correction Any pointers to a suitable battery operated DC VFD in the market? It is not as you say. Starting, It will be: KVA = 415 * In * 8 * 1.71/1000 KW = 415 * In * 8 * 1.71 * 0.25/1000 You have to consider cos phi will be round 0.25 at start. Inrush current will be much higher that you measured, round 8 times nominal current. Edited November 15, 2019 by Javi Martínez Kilowatt Power and Youda 2 Quote Link to comment Share on other sites More sharing options...
Gabriel_2018 Posted November 15, 2019 Share Posted November 15, 2019 If you want to get a good measure of inrush current, you can lock rotor while 2 or 3 seconds and measure current. But I don't know if the pump is accessible... Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 16, 2019 Author Share Posted November 16, 2019 9 hours ago, Javi Martínez said: KVA = 415 * In * 8 * 1.71/1000 Inrush current will be much higher that you measured, round 8 times nominal current. Many thanks for this additional info. Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 16, 2019 Author Share Posted November 16, 2019 11 hours ago, Javi Martínez said: But I don't know if the pump is accessible... Nope. 150m below ground. Quote Link to comment Share on other sites More sharing options...
phil.g00 Posted November 16, 2019 Share Posted November 16, 2019 Use a CT & the "Max" function on a multimeter, measure at the top while starting. Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 16, 2019 Author Share Posted November 16, 2019 11 hours ago, Javi Martínez said: As I said before, you only need a solar VFD and 15 Kwp of solar pannels. No batteries, no charger, no inverters... https://www.zuendo.com/ls-solar-trifasico-380-v/2863-variador-de-frecuencia-solar-trifasico-11-kw-ls.html I had this in mind and had even proposed the INVT GD100-011G-4-PV solar pumping inverter with 16S3P Jinko 330Wp panels (total 15840Wp) but the client wants to be able to run the pump at night. Needless to mention, doubling or even tripling the installed 20m3 water storage tank capacity would have been the best route to follow. Quote Link to comment Share on other sites More sharing options...
Kilowatt Power Posted November 16, 2019 Author Share Posted November 16, 2019 5 minutes ago, phil.g00 said: Use a CT & the "Max" function on a multimeter, measure at the top while starting. UNI-T UT216C clamp meter has an "inrush" function. The "max" function would measure the maximum steady state current which would be around 23A. Quote Link to comment Share on other sites More sharing options...
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