On Wednesday, March 09, 2011 08:02:40 PM Jon Elson did opine: > Kirk Wallace wrote: > > It might be hard to find a VFD rated higher than a few HP that can run > > on 240VAC input. > > http://www.automationdirect.com/adc/Overview/Catalog/Drives/GS2_%28115 > > _-z-_230_-z-_460_-z-_575_VAC_V-z-Hz_Control%29 Short URL: > > http://alturl.com/qhdpo > > I am running an 11 KW Toshiba VFD on 240 single-phase, and it is > perfectly happy. A few models have phase loss > detection, and will fault if they don't have all three phases. Most > under 10 Hp don't seem to have that problem. > You do need to derate the drive for single phase, if it is not designed > for it. But, remember, these drives are designed to run inside cabinets > at 40 C, 20/7 for 10 years or so. That is not typical home shop duty, > so the drive gets a big break by not running all the time at full load. > > > The higher HP drives seem to need 460VAC. I bought a VFD from eBay and > > No, there are drives up to 100 HP for 240 V supply. These will cost a > FORTUNE, even on eBay. The 480 V drives have transistors rated for half > the current and twice the voltage, and they are a lot cheaper. Most > industrial sites with 100 Hp motors have 480 power. The current draw of > a 100 Hp motor on 240 V is about 330 A per line! Yikes, the transistors > must be the size of a brick! > > > Jon
I am wondering where you got those figures Jon? At one tv station, KNXE, channel 19 NE of Norfolk NE, the klystrons coolant was cooled by a radiator about 4 feet wide, a foot thick and about 10 feet long, which had a quad of 16" torrington wheels on a long shaft, each wheel a good foot wide, turned by a 3 phase 220 volt 20 HP rated electric motor to pull cooling air through it. The FLA according to the nameplate was 39 amps/phase, and we adjusted pulley sizes seasonally to keep the motor running within a couple of amps of that 39/phase. Warmer air weighs less, so we could up the motor pulley about an inch in the summer, but had to drop it back come cooler weather which made it denser. One morning in the spring after I had put the bigger pulley on the motor, the exit louver failed to open, the honeywell modutrol motor had failed. It ripped the lead anchored lag bolts, about 36 of them, right out of the 12" thick cement blocks surrounding that 4x8 foot louver and blew it out in the back yard about 6 feet. That was fun putting that back in while 50+ mph hot air was coming out. Lots of heavy timber cribbing involved. But that was a 20HP motor, running on 235V 3 phase, and drew 39 amps/phase at rated power output. So a 100 HP motor would have needed only 195 amps, not 330/phase. That much heat differential has got to make smoke I'd think. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> Has everybody got HALVAH spread all over their ANKLES?? ... Now, it's time to "HAVE A NAGEELA"!! ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
