Lathe VFD Addendum: How to Tune Acceleration and Braking

welcome back to cloud for tea - I'm James we just finished a six-part video series putting a variable frequency drive into this grizzly geo 6:02 lathe and before I use it for a project I just wanted to spend a little bit time tuning the VFD to see how fast I can get the spindle to start and stop I wasn't planning on making a video for this but as I started fiddling with it and reading through the manual I realized there might be other people interested in this process as well so I'll go ahead and roll some cameras on it and if this turns into a video I'll post it otherwise you won't be seen this right now I've got the three jaw Chuck on here and this is actually the lightest check that I have for this lathe my 4 jaw is bigger and quite a bit heavier so in order to do the tuning and have it actually be useful I'm gonna go ahead and put the heavier 4 jaw Chuck on here and mount a piece of stock in it that's typical of the work that I do and then I'll move some cameras around and bring you back and we'll spend some time trying to tune this and see how fast we can get the spindle to start and stop ok got the 4 jaw Chuck set up in the lathe then I got a piece of it's about 12 inches of one-inch 1018 steel in here this is a typical kind of piece that I turned give us some mass I've got the variable frequency drive and we set it here to 60 Hertz which will be kind of normal 100% speed on the motor and then let's take a look at what I have set for the acceleration and deceleration times okay Corey the manual the acceleration and deceleration are 0 0 14 and 0 0 15 okay it's your 0 14 3 seconds and 0 0 15 also set to 3 seconds now the interesting thing as we're accelerating and decelerating this thing is to watch the DC voltage on the VFD so let me just set the mode so we can see that so that's the voltage on the DC bus the VFD 338 volts and let me just pop this into forward and then let it come to a stop so it'd be a three-second acceleration and a three-second deceleration and let's see how that works so the acceleration was nice and easy easy celery also at three seconds nice and easy let's see if we can accelerate faster whoops wrong one okay fourteen let's take this down to take it down to two seconds to see how that works [Music] again that was that was no problem at all so we can go further if we go down to one second oops okay that was pretty fast in fact that is way faster than this laid was able to accomplish with the original motor that was in this thing I mean that thing took several seconds I don't know if I'll be able to find a clip but you can look at previous videos it took several seconds to ramp up and this is going up in one second I'm tempted to push it further let's see what it'll do before we do that let's look at the current so that's three hundred thirty-eight volts I'll see how many amps that's pushing I was just over three amps if I read that correctly [Music] that was almost 4 amps so during the acceleration we're definitely pushing it pretty hard we're pushing it up past the rating of the motor into the overload capacity so I think that's probably about as far as I want to go let's look at the deceleration and see what we can do there so that's gonna be I can push the right buttons zero zero 15 that's three seconds let's take it down to two seconds oops again watch the voltage because on deceleration what's happening is the drive is over us keeping the motor ends up overhauling the drive because you have all the rotational energy in the Chuck and that is going back into the motor and feeding back into the VFD this VFD has an internal braking transistor it does not have an external braking resistor so it doesn't have a lot of capacity to dissipate that so it's just going to dissipate it with the transistor into the heatsink and so there's a limit to how much energy it can absorb coming back in so by lowering this to two seconds it's going to be driving the voltage on the DC bus up now right now we're looking at a voltage of about 338 I believe the ultimate cut out is around 380 where it'll just cut the load loose and let it let it spin down on its own so let's go ahead and spin it up and then turn it off and let it spin down see if we can bring it down in two seconds we can watch the voltage here [Music] and it looks like the voltage was climbing and we just hit the over voltage cutoff and it was largely slowed before that happened but we definitely hit the cutoff so I mean reset and watch again just see how close that really is [Music] yeah it's definitely hitting that 380 pretty quick so let's lengthen this out slightly there 1/2 second what will that do well that seems to work that gets us up there still gets it stopped two and a half seconds try reverse I can live with that let's see let's torture test this thing take this all the way up to 120 Hertz got the knob turned all the way around let's go into full reverse and then we'll reverse it and go full forward [Music] [Music] that's pretty good I'm totally happy with that now you could hear a little bit as it was coming up to speed in Reverse it wasn't quite getting there so I think that one second is a little bit too aggressive let me lengthen that two a second half again we're talking about half a second here let's see how that fares again all the way up at 120 [Music] [Music] [Music] you know to be honest I'm not sure I noticed that much difference I think that one second might be just fine let's try 1.2 I'll watch the current this time into reverse [Music] and forward okay and it won't reset me uh oh it's because I'm still in forward there we go okay well um I think I need to lengthen that just slightly and I'll fiddle around with this a little bit and then bring you back okay I've been playing with this a little bit and what I've altum at least settled on I think just to keep this in the safe mode so that I'm not you know messing around with it and struggling as I work is I've got the acceleration time set to one second which is fine it's one second to sixty Hertz or two seconds to 120 and then I have the deceleration time set to four seconds and when you've got this much moving out here it just it generates a lot of energy to goes back into the drive and this drive doesn't have an external braking resistor so it's just got no place to dump that so when I have it set to this if I'm running at around if I'm running at 60 Hertz hang on so if I'm running at 60 Hertz this thing will come up in one second and then it'll break down in four and I think that's just gonna be fine so here's going to reverse and then switch me to forward [Music] four seconds one second up four seconds to stop and you can see if I show the voltage here it's it's handling this easily [Music] that's probably the highest spike I've seen Stu it one more time [Music] yeah I'm staying well under the whoa maybe not well under we're definitely staying under the 380 volts and so I think this is gonna work I have spent a little bit of time playing around there's a bunch of other settings on this VFD if you get into this and look through the manual there are there's something called regeneration prevention and you can set voltage levels at which you know like when it's decelerating or when it's Overhaulin it'll go ahead and bump the frequency up a little bit and I played with that and it just isn't really giving me what I want I you know it ends up the jeeringly going down and and slows down much much slower tried some of the tuning couldn't really get anywhere with that there's also some settings in here to be able to change the the braking transistor on level right now it's set so the braking transistor comes on at 380 and shuts off at 340 well let's play with that and see if we can lower that a little bit so that's a 320 of three not the most usable user interface ever and that's set at 380 and you can see we were touching up against 380 during the breaking so let me go ahead and lower that to maybe 360 so the breaking transistor will turn on at that level and let's see what that does and again we're still sitting at 60 Hertz so going forward it doesn't appear to have made much difference let's see if we can lower the frequency at all now or lower the time okay we're set for seconds let's bring it back down to three watch the voltage [Music] and it really doesn't help I think we're kind of at the limit of what that resistor what that transistor can do to dump this so set it back and I'm just going to go ahead and set this back up to the factory default yeah maybe I'll leave it at 370 okay and let's just do one last test let's take the frequency all the way up to 120 Hertz let's watch the voltage run all the way up in Reverse which the forward and on [Music] okay I think I can live with that there are some other things that could be done but I think this is about as fast as we're gonna get it to stop with this VFD so I think I'm gonna leave it at that for now well I hope at least some of you found that interesting or useful as I said I was going to be doing the tuning anyway and I figured I might as well roll the cameras that's all I've got for today if you're enjoying these videos please give me a thumbs up feel free to subscribe to the channel and leave me a comment I'd like to know what you think thank you for watching [Music]

Channel: Clough42

Views: 27,393

Rating: 4.9617429 out of 5

Keywords: Lathe, VFD, Acceleration, Braking, VFD Wiring, Teco VFD, L510, Grizzly G0602, Westinghouse VFD, Teco-Westinghouse

Id: VtS24eyaqjQ

Length: 16min 8sec (968 seconds)

Published: Thu Jul 12 2018