[WilliamX]

I would appreciate it if anyone would be willing to take a look at these VFD parameters. I keep heating up the spindle during ramp up. The customer service at ATO has been prompt with replying, but I get the impression that they are also at a lost.

Problem: over current during acceleration. During acceleration the amps increase to 14.6 amp before slowly coming down. This is a 4 amp spindle. The spindle also wants to keep ramping up to max speed and not stop at around 6000 (110Hz).

VFD: ATO em15 series. 1.5kw, 120v 1ph to 220v 3ph.

Spindle: Mechatron HFS-6508-AC. 0.8kw, 4amp, 230V, 24000 rpm, air cooled.

VFD parameters are from ATO, the manufacturer. They, and I have checked them multiple times, but cannot seem to find the problem.

Selected Basic parameters:
-constant torque load mode
-keypad control
-max frequency source: keypad potentiometer
-preset frequency: 110Hz
-maximum frequency: 400Hz
- frequency upper limit: 400Hz.
- freq. lower limit: 110Hz.
- carrier frequency: 4khz.
- accel. Time 8 sec.
- decel. Time 8 sec.

Selected spindle parameters:
-variable frequency asynchronous motor
- rated motor power: 0.8Kw
- rated motor voltage: 230v
- rated motor current: 4 amp
- rated motor frequency: 400Hz
- rated motor rotational speed: 24000

If anyone notices a mistake, or has a suggestion, please let me know. We are a small shop and run several CNCs. I bought 2 of these spindle/VFD combinations to upgrade 2 smaller CNCs, expecting to do the upgrade in one weekend…. It has been 5 days now with no progress.

William

[joeavaerage]

Hi,
I run that exact same spindle, and have used it and used it for many thousands of hour over ten tears, simply brilliant.
I use a 750W Delta VFD.

There are a few things to think about, firstly how fast are you ramping up the spindle. The faster you ramp up the more the current. I have mine set fairly leisurely at 6 seconds.
I would suggest a fairly leisurely ramp down time to, to avoid a large voltage surge back into the VFD when decelerating.

I think the more likely cause of your issue is that you have not correctly set the V/F curve. Most VFDs are set at factory defaults of applying full voltage at 60Hz. This would be normal for
a standard induction motor. You spindle however expects full voltage at 400Hz, and some part voltage at lower frequencies. I suspect that you have not programmed that part
correctly an therefore your VFD is applying full voltage at a much lower frequency than it should resulting in much higher currents.

You need to review the settings to find which of them describe the V/F curve. I know which parameters describe that in Delta VFDs but have no idea about ATO?

A huge number of happless souls have misunderstood this, not programmed the VFD properly, hooked up their brand new spindle and blown the sh****tter out of it. Don't do it.
You are risking your brand new spindle. You have paid a premium to get a German made spindle.......why economize on the VFD?

Craig

[joeavaerage]

Hi,
this is the parameter description of a Delta B series VFD.

Note, and especially important is the parameter 01-01. It sets the frequency 'base' at which to apply full voltage. As I explained earlier it is set to 60Hz by factory default,
but that would mean that at 60Hz full voltage would be applied to your spindle. That will let the smoke out of it for sure. That setting needs to be changed to 400Hz.
Note, less importantly but you can also set a midpoint in both frequency and voltage, so you can in effect program a curve into it. Not sure there is any advantage
to doing so with our spindle, I have not done so. That means the voltage ramps from 0V at 0 Hz up to 220V at 400Hz, ie linear.

Actually minor correction: the midpoint frequency is set by default to 0.5Hz and the output voltage at that frequency of 1.7V. Near enough to 0V at 0Hz.
So the midpoint is effectively the start point, at least at factory defaults, as I have left mine.

Craig

[WilliamX]

Thanks for that information. I never thought about the V/F curve... it sounds like a possible cause of the over current. The only problem is that I cannot find any parameter for the V/F curve. There have been other parameters that I couldn't find, like the number of poles.
ATO told me that the parameters listed in the manual are the only ones I need to set. The other ones will adjust automatically. I just sent them an email asking about the V/F curve... hope they can tell me where to adjust the parameter.

I didn't think I skimped on the VFD.. I went with ATO because they actually answered my questions. I think cost wise the ATO VFD is comparable with Delta.. maybe even a little bit more. I don't know if the problem is the VFD or me.. although I've never had this problem before with our other HF spindles.

I have the acceleration and deceleration set at 8 seconds. I think that should be acceptable for this spindle.

[joeavaerage]

Hi,

I think cost wise the ATO VFD is comparable with Delta.. maybe even a little bit more.

Delta have been in the market for twenty-thirty years, ATO....well not so much.

If that is the case then why cannot they answer the question? Surely the V/F curve of a VFD is absolutely fundamental to the operation of a VFD and
they should know that.

Do you have a manual? Is it in 'Chinglish'? Does it have a description of the parameters?

Just about all VFDs are the same, that is if one manufacturer has an idea or feature then all the others get on the case also. Give that setting the V/F curve is so important
surely they would have a description of it.

I have the acceleration and deceleration set at 8 seconds. I think that should be acceptable for this spindle.

Agreed.

I would avoid powering your spindles until you get this sorted, it would be a bloody shame to blow a spindle because you could not find the correct parameter to program.

Craig

[WilliamX]

The VFD's came with a manual. The thing is that the parameters listed (and explained) are selective. The manual lists and explains maybe 14 parameters, but the VFD has 27 of them for that section. Like I said, they told me that the ones not listed in the manual adjust automatically....

I am still waiting for them to get back to me about the location of the V/F curve parameter. After 6 days, my patience is wearing thin...