On Wednesday, December 28, 2011 11:21:24 AM kqt4a...@gmail.com did opine: > I have a 40v 10amp power supply from Probotix > I asked this question of supp...@probotix.com > > > I have used your 40 volt 10 amp power supply for over a year with 3 of > > your yellow motors (3 ammps each) I just added a 4th driver to my > > controller with the intent of adding a 4th 3 amp motor for a rotary > > table How is the 10 amp power supply going to handle 4 - 3 amp motors > > Am i looking for trouble > > I got this response > > > The 40V 10Amp power supply is more than capable of handling all 4 > > drivers running the 3 amp motors. The formula breaks down like this: > > 3A x 4 x 60% = 7.2 amps This would be what your draw would be on the > > power supply. > > Would someone elaborate on this just a bit > I am not questioning their response I just do not understand it > > Richard > Each motor may have a 3 amp current flowing, but due to the current regulation of the chopper in the driver, with its free-wheeling diodes effect, much of that 3 amp current is circulating current between the motor and its driver, with, when the motor is stationary, only perhaps 400 milliamps actually coming from the supply when averaged. Enough to make up for the resistive heating losses in the motor and driver.
Steppers working hard at higher rpms will draw more, but in the real world all 4 motors will never be running full speed continuously. If you could put a meter into the line and measure it (not recommended because the inductance of the meter will mess with the chopper waveforms back and forth into the supplies output filter capacitor, and that could destroy a driver package from overvoltage spikes on its supply input) I would doubt very seriously that you would ever see more than 4-6 amps to run all 4 motors at a good clip. There are hall effect based ammeters that could measure the current this current without the inductive effects, but they are above the range of everyone having one in his tool kit, purely laboratory instruments that in 60+ years of troubleshooting electronics, I have never felt crippled by not having one of them in my kit. As the folks here have taught me quite a few times, the cat has more than 9 lives because there are usually more than 9 ways to skin him. One can often get answers for this sort of problems from the display of an oscilloscope if you know how to read what it is telling you. IOW you should be fine. > ps - I tend to bring many non-emc related questions to this list > If there is a more appropriate place please point me to it While this could be OT for this list, it is not OT for quite a few of us here. I am more than happy to teach a wee bit about electronic subjects where I have some BTDT experience with them. Trying to pay back for some of the help that the real machinists here have given me over the years. Backscratching as it were. It is mutually pleasurable. :) 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> Well, O.K. I'll compromise with my principles because of EXISTENTIAL DESPAIR! ------------------------------------------------------------------------------ Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex infrastructure or vast IT resources to deliver seamless, secure access to virtual desktops. With this all-in-one solution, easily deploy virtual desktops for less than the cost of PCs and save 60% on VDI infrastructure costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
