On Monday 21 August 2017 15:31:41 David Berndt wrote: > On Sun, 20 Aug 2017 18:09:20 -0400, Gene Heskett > <[email protected]> > > wrote: > > On Sunday 20 August 2017 03:40:56 David Berndt wrote: > >> I'm having some issues commissioning my HY VFD. 4kw unit driving a > >> 5hp 3450rpm motor at 30hz max frequency (temporary 2 pole motor, 4 > >> pole motor is in the mail). Works great in "forward", but when it > >> accels in reverse it trips out and throws an E.OC.N error. Which > >> appears to be an over current error. > >> > >> I've flipped 2 leads to the motor, reversing the physical rotation > >> and it still works great in vfd "forward", proving that the motor > >> and mechanical aspects work in both directions. But the VFD does > >> not. Accel times are quite conservative/slow. Problem happens about > >> 1 second into acceleration. No clue.... There don't seem to be any > >> relevant settings. Problem happens regardless of control method, > >> modbus or operator panel. > >> > >> Unrelated, but wow, at low speeds this VFD seems to throw off a ton > >> of interference. The symptom I've noticed is that my usb mouse > >> connected to the PC in the control cabinet that also houses the VFD > >> basically gives up on life if the motor is running below 15hz. USB > >> dongle modbus was fairly impacted as well until I grounded the > >> cable shield to the pc case. > > > > I had noise worse than the coaches megaphone, so I put a 20 amp > > rated Corcom brick wall in the AC line feed. Works a treat. > > Any particular series you picked? Does it really matter? I assume some > filtering, even one of the corcom filters rated as general purpose > would be better in front of the vfd than nothing at all? > > >> Just to make this slighlty more on topic. Is there a config > >> somewhere for maximum spindle RPM? With the drive configured > >> correctly it won't overspeed the motor, but it would be nice if the > >> software was aware of a top end for spindle speed as well. > > > > What are you using for an interface between the pwm (or pdm) gen, I > > am assuming the pwmgen is in a mesa interface card?. > > It's just a usb to modbus dongle. So the hy_vfd user componenet. I > realize there are ways to solve this in HAL but none of them seem to > enforce the same way softlimits do, or I'm doing something wrong. I'm > looking for something that will throw an error and power off the > machine g-code sets and S command too high, or the manual control > screen is used to set the rpm too high (ideally the interface would > just stop increasing the spindle speed once it hits the max...). > > > I had been assured by the ebay critter that sold me the 1.5 hp vfd, > > hooked to a 1 horse 3 phase motor from a 30 yo compressor, that the > > analog input filtering was good and that I could feed the analog > > input (0 <-> 5 volt range, it has both 5 volt and 10 volt inputs) > > directly from the pwm generator, but I was unable to get good smooth > > control. > > > > My motor is a 4 pole, and at light load it has been spun north of 7K > > rpms. No damage if the internal fans don't throw blades, but > > because of motor winding inductance, current draw is well under an > > amp/phase so usable torque is an oxymoron, there isn't much. > > Practical limit for my setup is about 140hz. From 8hz to 140hz > > doesn't make me switch drive belts from 1st gear, no backgear. > > I don't plan to run a great range of motor speeds, but getting it up > to 90hz to pickup some spindle speed would be nice if the gearing and > spindle will take it. On the low end, if something like 20-30hz would > be usable I'd probably be satisfied, just enough to limit trips ot the > back of the machine to throw gear select levers.
In my counterfeit vfd, I do have max and min frequency settings, anything above max from the computer is limited to that, and I'd expect you'ed be fine with a 140 HZ maz. Below the min, it shows on the display but doesn't actually power the motor until the requested speed is above whatever minimum you've set in the vfd. Mine does have a modbus port, but I'd expect that to be similarly limited. Down on the creep end, I am not using enough low speed torque boost to feed the motor more that its nameplate FLA*1.2, primarily because at those speeds the motors internal fan is worthless. And I subconsciously limit that on time to whats reasonable for motor temps 20 minutes por so before I cop a feel, as this motor has only 40% of the mass the 3/4 hp I took out, so it heats faster. So far so good. :) But I've a spare just like it. One of those the price was too good not to buy both of them deals. As for accel and decel times, cut them in half, try it, and keep cutting the times until it errors, then add a second at a time until it quits erroring. I can do a full reverse with about 1 turn of overshoot ( I have some hal trickery that gives me the overshoot in encoder edges ) at 200 chuck rpms. Thats quick enough to do rigid tapping at 150 chuck revs. Since my spindle is threaded, I've made some clamp rings to lock the backplate to the spindle flange so I'm not worried about unscrewing a 35 lb chuck. Some vfd's will have a breakpoint where they switch to a different set of acell/decel curves. You'll learn in due time where to set that breakpoint for best results. Mine has no braking resistors, its all dynamically 4 quadrant control but does use dc braking at low speeds. > > I had a mesa spinx-1 I had taken out of TLM because I was putting in > > a 40 lb supply and one of Jon's (Pico Systems pwm-servo amplifiers, > > great device BTW), so I pulled it out and hooked it up. Works > > Perfect. With a bit of tuning in the vfd, I can even do rigid > > tapping on the old grey Sheldon up to around 200-250 spindle rpms. > > Above that and the overshoot at reversal exceeds a full turn of the > > chuck. > > > > The spinx-1 needs separate fwd and rev signals, not a problem to > > hack that in your .hal file, but yell if you need some snippets of > > hal code, I might be able to help. > > > >> Thanks, > >> Dave > > > > Cheers, Gene Heskett I'll be out of pocket at a funeral home the rest of the evening, I hope this is some help in the meantime. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
