Most, if not all, VFDs have a speed ramp up that is programmable. So you can set the starting amp limit to whatever you want within certain bounds.
From: Mark Radabaugh Sent: Friday, June 4, 2021 4:52 AM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] Fort Bliss lift station troubleshooting No, AC motors don’t work that way. Though you have the right idea, it’s just called a variable frequency drive. Rectify the AC into DC, stick it in a big capacitor, and turn it back into AC at whatever frequency you want the motor to spin at. Slowly ramp up the speed and it takes a lot less energy, at least in a pumping application. Or really any application where starting the load moving doesn’t require a lot of breakaway torque. Mark On Jun 3, 2021, at 10:28 PM, Steve Jones <[email protected]> wrote: I assume you cant just put a massive capacitor on it? On Thu, Jun 3, 2021 at 7:14 PM Jaime Solorza <[email protected]> wrote: Exactly...that's what they messed with it. On Thu, Jun 3, 2021, 5:56 PM Chuck McCown via AF <[email protected]> wrote: Systems I worked on like this had an alternator circuit that would make two main pumps take turns each operation. I also worked on remote C.O. buildings that had dual HVAC systems. After a power failure the generator would come on but it could not start both systems at the same time. I had to put a cut out on one of the HVAC systems to kill it if there was a commercial power outage. Unless you work with large motors, you have no appreciation for starting loads. From: Jaime Solorza Sent: Thursday, June 3, 2021 5:02 PM To: AnimalFarm Microwave Users Group Subject: [AFMUG] Fort Bliss lift station troubleshooting After going through the drawings and consulting with original design engineer on this project installed in 2007, we found one issue right away...the water company techs made some changes to try to get pump 3 and 4 to run simultaneously...kept tripping breaker. The system was designed for 600amps maximum but when pump 3 starts up it goes above 600, drops and stays at around 204.x while working, then when they turn pump 4, it starts up above 600amps and trips breaker. The system was designed to work with pump 1, a smaller motor and pump 3 , and pump 2, same as 1, works with pump 4. On Monday, we will rewire to original design and make some changes to PLC programming and relays....they need some better level transmitter installed but that's another project. BTW, the enclosure is water tight and under a canopy for added protection. -------------------------------------------------------------------------- -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com -------------------------------------------------------------------------------- -- AF mailing list [email protected] http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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