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Powermatic Deceleration Problem

B

Brent Sobotka

Joined
May 8, 2019
Messages
27
Likes
21
Location
Buffalo, WY
I recently bought a used Powermatic 3520B. The gentleman I bought it from gave me a very good deal on it because it had some problems. I’m not sure what initiated the problems, but when I bought it, it would only spin up to about 1400 RPM’s, and the deceleration\braking didn’t work. With the help of Powermatic’s tech support, he threw every new part they could think of to fix the problems, short of a new motor. They couldn’t fix the problems. He finally got tired of messing with it and bought a new 3520C and sold me the old one.

As I began studying the problems, evidence began pointing towards a programming problem with the new VFD that they installed. The old Delta S model VFD that came on the 3520B was no longer available, so they installed a Delta E model VFD. It is the same VFD that they currently use on the 3520C lathes. I ordered the optional keypad that plugs into the VFD that allows you to read the parameters and edit them. As soon as I plugged it in, the speed problem was apparent. The Maximum Output Frequency was set at 60 Hz. It should be about 135 Hz. I changed that, and it instantly fixed the speed problem. 3200 RPM’s. The deceleration parameters were also wrong, so I changed them, relative to what they would have been on the S model VFD. That didn't fix the problem. No braking at all. It takes about 35 seconds for the lathe to stop from full speed with just a chuck on it. I double checked all the parameters and can’t figure it out. I checked the braking resistor. It checks good with 200 ohms just as it should.

The E model VFD has a whole bunch of acceleration/deceleration/braking parameters that the old S model didn’t have. My guess is that one or more of these parameters needs to be set to turn the deceleration on. I contacted Powermatic to ask them if they would send me the programming parameters for a 3520C, which will undoubtedly have this issue addressed. They said they don’t know, as the VFD’s come to them preprogramed from the factory and they don’t know what the individual parameters are, and they don’t even have access to them. They did have a small list of a few parameters, and they sent me those. I checked them and changed any that I had different…no joy.

So, would anyone out there have a list of the VFD parameters for the Delta E model VFD for a 3520C? Or are there any other things I’m missing?
 
Cant help you with your problem other than to tell you that I installed an aftermarket VFD on a Nova lathe. Near as I could tell there were 3 different parameters that all acted like decelation or what I call electronic braking. It's been too many years to remember what it was.
 
My guess is Powermatic does the same thing as Grizzly with regard to VFD's. Grizzly buys VFD's pre-programmed from the manufacturer. The parameters are determined by the lathe designer and password protected. Even Grizzly service doesn't know the secret password. Without the password certain critical parameters can not be changed for user safety. There is usually a way to override the password by purchasing a special cable from the VFD manufacturer and connecting to your PC.

Your best bet might be to find a retail dealer of Delta VFD's for advice. By retail dealer I don't mean the online sellers of inexpensive VFD's.
 
Thank you for the responses, I've been using that manual. The problem is that there are so many parameters, and I'm not smart enough to figure out what a lot of it means. Many of the parameters are different from the old VFD and from the 3520B. There are whole bunch of parameters that are related to acceleration, deceleration, and braking. This VFD is designed to do a lot of different things in a lot of different applications. I suppose I could just try turning some of these parameters on and off at random and see happens. I'm a little nervous about damaging the motor, but the likelihood of that happening is probably minimal. Maybe I'll try.

There is a password on the VFD, however I have it, thanks to the search function on this forum. Powermatic also sent it to me. I bought a little $30 keypad that is an option for the VFD that plugs directly into the VFD, It allows you to input the password, read the parameters and edit them without plugging in a computer.

Powermatic confirmed to me that they do indeed purchase the VFD's preprogrammed from the manufacturer. That is why they don't know how to program them. Unfortunately, this is where this problem originated. This VFD was purchased directly from Powermatic. It was preprogrammed. But it was wrong. There is no way that the guy I bought the lathe from was into the programming. The first thing I saw when I plugged the keypad in was that it was set to 60 Hz. That had to come from the manufacturer. My trust level is low that everything else is correct.

Right now, I think my best option is to find someone with a 3520C and plug my keypad into the VFD. Copy down all of the parameters, then compare those to what I've got. The problem is, in rural Wyoming, there aren't a lot of other woodturners, let alone woodturners with that specific lathe. I built a spreadsheet with the Delta factory default settings and the settings that I currently have. Once I get the Powermatic settings I'll put those in there. So, if this question ever comes up again, the data will be available.

Fortunately, the lathe works. It just takes a a while to slow down, and it is just a second lathe for me.
 
Brian, I admire you for having the courage to take on this project lathe, and even more for your success in solving most of your problems. If the prior user did not have the Max Output set correctly, then those working on the VFD were not expert in programming it. Which raises the possibility that they reset one of the more exotic parameters, which are way over my head, but appear in the manual as graphs and curves. There are electrical engineers on the forum and experienced industrial VFD users here on the forum, so hopefully you will get the help you need.

One alternative would be to find out the seller of the VFD and ask their tech support for help. The seller we've used charges $25 for a half hour of hand-holding, and it might be well worth the price in your situation, especially with the reduced amount you paid for the lathe.

Great work, and good luck.

EDIT: Just read your most recent note--Do NOT start turning on and off parameters. Instead, check to see if they've been changed from their original, default mode. If you find one, and it's not among the 6 or so parameters that need to be changed to run a powermatic, try restoring it to the default setting. Unfortunately, I don't have my paperwork with those 6 or so parameters and their settings at home. I can get them Tuesday, if that will help.
 
Well, I can't tell you how to fix the problem, but I had issues with the electronic braking on my old 3520A. Called up PM, still in country at the time, and the tech walked me through adjusting the braking. When in the high speed range, when I turned it off, it would trip the overload or what ever it is in the phase converter, and turn off the lathe. We adjusted it for a longer breaking time. Problem solved. It didn't do it when in slow speed range.

robo hippy
 
If you have the software to communicate and program the VFD with an external device, you should be able to save the parameter settings
to your external device (laptop) and then review the settings one by one and make changes as needed. You can find another lathe that is
working correctly and save those parameter settings to a file and then compare them to your VFD file settings.

A similar process is to review the parameters one by one and write them down on a sheet of paper. Find a similar VFD and review each parameter
and write them down one at a time and compare the (2) sets of parameters and identify the different settings and make changes as needed.
If your VFD has an onboard display you can usually review the parameter settings one at a time and write them down. Some VFD's do not have an
onboard display and requires an external device to view the parameters. Some VFD's will use a HIM Human Interface Module to communicate with the
VFD to review parameters and make changes. This HIM simply plugs into a socket built into the VFD circuit board. This is an additional cost when purchasing a new VFD but allows replacing the HIM when the LCD display goes bad. A VFD with a built-in LCD display and keypad can have problems as the device ages and require replacing the built-in LCD display or keypad when they wear out, this can require sending it in for repair or replacing the entire VFD assembly. The lower cost VFD's do not have these built-in features and require an external device to communicate and make changes.
 
Somewhere I have a printout of all the preset parameters (plus my modifications for lower min RPM, etc.) from my 4224 VFD. It was sent with the same VFD (and motor) as the 3520, so it should work for you. I have it on my other computer or a backup drive, so I'll have to dig it out. Send me your email and I'll pass it along.
 
These are the parameters that seem to have some association with deceleration, along with the default setting from the Delta manual, compared to the value that is currently programmed. Perhaps it will make sense to someone smarter than me.
Delta E Model VFD Parameter Settings
Group
Number		Parameter
Number		Delta Factory
Setting		User
Setting (Reading)		Explanation
00.08
0​
506​
Password Input
01.0910.05.0Accel Time 1
01.1010.05.0Decel Time 1
01.1110.010.0Accel Time 2
01.1210.010.0Decel Time 2
01.131.01.0Jog Acceleration Time
01.141.01.0Jog Deceleration Time
01.156.006.00Jog Frequency
01.1600Auto acceleration /deceleration
01.170.00.0Acceleration SCurve
01.180.00.0Deceleration SCurve
01.1900Accel/Decel Time Unit
02.080.010.01Accel/Decel Rate of Change of UP/DOWN Operation with Constant Speed
03.110.000.00Brake Release Frequency
03.120.000.00Brake Engage Frequency
06.140.50.5Deceleration Time of Output Phase Loss
06.160.10.1Detected DC Brake Time of Output Phase Loss
08.0000DC Brake Current Level
08.010.00.0DC Brake Time during Start-Up
08.020.00.0DC Brake Time during Stopping
08.030.000.00Start-Point for DC Brake
08.1800AVR Function
08.19380.0380Software Brake Level
 
As Robo mentioned above, you might eliminate the problem by increasing the decel time, and setting Decel time 1 to 10 seconds. This would be very safe to do, and can easily be reversed.

None of the parameters below decel time 2 in your chart should need to be anything other than default or be changed.
 
I bumped the decel time up to 10 seconds as Dean and Robo suggested. No effect. I also unplugged the machine to ensure everything was reset. Again, no effect. I'm beginning to think this VFD may be defective. It was purchased new from Powermatic last October. It hasn't worked properly since day one. They were primarily chasing the low-speed problem. I fixed that by upping the frequency. However, that tells us that there was at least one problem coming out of the Delta factory where it was supposed to be programmed. I'm going to contact Powermatic tomorrow to see if there are warrantee options. They may not do anything, since I wasn't the original purchaser. But I do have the invoice. If they won't do anything, I'll try Delta. If that doesn't work, it looks like these things are available on Ebay for around $150.
 
There should be a parameter to turn off password protection and you don’t need the password to do it. I have never programmed a Delta VFD but that has been my experience with other brands.
 
I think I prefer having the password protection on. It prevents me from making unintended edits when I'm just perusing stuff. Inputting the password is pretty simple when I want to change something.
 
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