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View Full Version : Yet another VFD question ;) and on my first post!!!



Matt F
02-05-2018, 09:43 PM
Hello all...

Avid lurker, first time poster.

A few months ago I picked up my first lathe, a Colchester Master Mk2. It's been around the bush, but at least the ways are pretty straight, there is a damaged lead screw midsection... and a bit of slack in the compound (cross-slide is tight). All in all it was a great buy (steal?), and I am happily making a mess of a ton of steel. I'm even getting to the point where I'm working on getting a good finish cut... so I'm making progress. :) The most fun has been fixing the lathe, with the lathe!

My issue is electrical...

It came with a 220v 3hp 3 phase motor. Switched over at some point in it's life from a 540V (I'm in Canada). Of course, no 3 phase to my residential dwelling (no the lathe is not in the kitchen, but it's close! ) So I purchased a VFD from manufactured in another continent... cheap (only slightly less then I paid for the lathe... ;). 2.2kw model, 10 amps, 220v single phase to 220v 3 phase

The vendor (Lapond) has been great to work with, always getting back promptly. They even upgraded the VFD at no charge to the "better, more robust model" in the same size. (its flat black which makes it so much cooler... ;) I think I'm starting to get on their nerves though!

My issue is the lathe (VFD and motor) works great in lower gears - I can make some pretty heavy cuts, no problem, even in T304 stainless - but it won't spin unloaded above 500 rpm??? If I engage the 750 or 1200 rpm settings, the VFD/motor bogs out after about 30-40 Hz.

The only chuck I have is a big 8" 6 jaw, but I would think that it should be able to at least just spin that???

THe VFD is impressive in its capability, I have a bit of programming knowledge and this thing can do a ton of cool stuff!!! (if the manual is true ;) ) and it runs an "auto tune to your motor" feature. Here is the strange part. Factor settings work better then after the auto tune, it will do some strange things after I run the tuning program. There are no error codes for the motor from the VFD (which the manufacture said it would diagnose if the motor was bad) But maybe the motor is bad in a way the VFD can't pick up??? no bad noises... very quite when in low gear and running full 60 Hz (so much so that I'm loving the fact I can make chips at 3 am, when it would be impossible to make sawdust without waking the neighbourhood!)

So I'm no electrical engineer...

I'm going on my google-fu that 220v 30 amps can produce 3 hp.... and my amp reading of 4 amps and no thrown breakers means I'm no where near the limits of the circuit...

Any thoughts? Any info I'm missing to help solve the issue?

Cheers!

Matt

George Bulliss
02-06-2018, 07:11 AM
Bump. Got stuck in the moderation filter.

J Tiers
02-06-2018, 09:15 AM
"Bogs"? Does it quit, or just refuse to go faster?

Model of the VFD? Would like to see on line manual.

CCWKen
02-06-2018, 09:18 AM
My first suspected part would be the motor "rewired at some point in it's life".

The second would be wiring in general. Such as size of wire and lengths of runs.

Do you have the ability to check voltages and motor rpm in a stand alone state?

As a side note:
My VFD driven puny little 1.5hp mill motor will spin up even with the shaft lock engaged. It spins in the belt.

Magicniner
02-06-2018, 09:52 AM
I had a similar issue with a Myford Super 7, 1hp motor and Siemens VFD where auto-detect would get the motor running but it wouldn't hit speed in all belt ratios, the solution was to enter the all possible plated ratings on the motor manually in the appropriate parameters.

J Tiers
02-06-2018, 11:13 AM
Putting in the basic parameters will indeed make the VFD "know" enough about the motor to allow it to do a proper auto-detect.

I would suggest that you NOT use the mode you may have it in now. Set it to a plain "volts/Hz" mode, which will allow you to make sure that the parameters it is using are all good. That mode may be fine for you, the fancier features can get in the way when getting the VFD running when you are new to VFDs.

What have you actually entered as parameters?

What exactly is the motor not doing, or doing? Does it stop, or just hold a slower speed?

Usually, you will need to enter some basics, such as motor rated voltage, motor rated current, motor rated frequency, etc. Those put boundaries on what the motor "is", making sure the VFD is in-line with what the motor needs. After that are parameters such as acceleration (how long a time the VFD uses to spin up the motor to speed) deceleration (how long the VFD takes to slow the motor to a stop), and perhaps others.

The VFD may do one of two things if it is "not happy", meaning usually that the current drawn is too high: It may simply shut off, in which case it should show a "fault code" that helps you understand the problem. Or, it may "current limit", continue to operate, but hold the current at whatever limit has been set, limiting power and speed. There should be some indication on the display of the current limiting condition, the manual will tell you.

When a motor has been rewound, a GOOD shop will show the new voltage, current, etc. Careless shops may not put any new label on, leaving you in the dark about what really was done.

It is very possible that the settings for the VFD are not correct, and that may be because you do not have good information about the rewound motor. Unfortunately, the VFD cannot detect everything, you need to give it basic information about the motor (from the motor nameplate if it still applies). Then the VFD can adjust itself (auto-detect) based on those basic numbers, so that it "knows" how to interpret it's measurements.

A 230V 3HP motor would be expected (per US electrical code) to draw about 9.6A at full load and 230V. If the current limit is set below that, your problem may be that setting. Same if the motor is not actually that rating, due to being rewound and not documented.

I should mention that the acceleration and deceleration parameters can have a good deal to do with operation at higher spindle speed, where the motor has to get a significant mass of material spinning at a high speed, closer to the motor's own speed. Sometimes it needs a longer time to come up to speed without going over current limits. Oddly, sometimes a FASTER acceleration is actually better, due to the way VFD current limits work.

MrFluffy
02-06-2018, 11:24 AM
It might be some limit in the software config, the vfd's on my machines are quite complex to tweak completely and a few times I have been searching through menu structures looking for some elusive parameter that I think might have been wrong. I entered the motor plate parameters in by hand also.

On another note, please research what the max you can spin that big old chuck at, some chucks especially larger cast iron ones have a upper rpm limit, and if you drive the frequency higher than standard for the motor or even spin it up in a high gear and exceed that limit, sometimes it can end badly.

Matt F
02-06-2018, 02:58 PM
Hi folks,

George!, thanks for bumping me out of purgatory!

Thank all for the replies!

Ah yes a few things like details.

Motor plate shows

208/220v
9 amps
60 cycles 3 phase
1730 rpm

All of these hard parameters I hand enter. This does not seem to make any difference in the operation. The problems arise when I run the auto tune after these hard parameters and the VFD checks resistance among other things. One oddity is the auto tune "mutual inductive reactance" varies greatly from testing static to dynamic auto tunes (I can auto tune with the motor still hooked to the lathe, or take the belts off)

Yes indeed the plain V/F mode works "better" then the "sensorless vector" mode. But the issue still occurs.

Note that I get a max reading of about 4 amps while trying to get it up and spinning.

Here is a better description of the issue.

All gears up to 500 rpm, the motor can smoothly accelerate either very slowly, or fast, I currently have about .5 sec from 0-60 hz, and this is no issue.

With the 750 rpm engaged, I can get up to about 45 hz before the motor starts to SLOW, and then there is a little bump at around 55 hz where it will try hard to speed up, but it gives out and makes bad noises (strain type noises)
If I move to 1200 rpm the same thing happens, but it moves down about 5 hz, so it will smoothly speed to 40hz and then strain noises and again a bump of torque at 50 hz

In both above cases, I ramp up manually the hz and this helps to get it higher rpm then the .5 sec accel, but not really by much, maybe another 10 hz.

The VFD is Lapond's model SVD-PS 2.2KW, it replaced their SVD-ES

I have not checked the motor wiring for Delta vs Star.

The wire should be good. It's 10 gauge solid wire, maybe a 30 foot run from the circuit breaker, through a safety switch, to the VFD, then maybe 6 feet total wire from the VFD to the the motor. The VFD connections are not the beefiest, but they are screw lock type, and I would assume be engineered to move enough current

Here's a link to the unit, I can't seem to find an online manual, I'll keep looking

https://www.amazon.com/LAPOND-Version-Inverter-Variable-Frequency/dp/B073WWG9BS/ref=sr_1_1?ie=UTF8&qid=1517947562&sr=8-1&keywords=svd%2Bps&th=1

http://www.soyan-tech.com/variable-frequency-drive-vfd/high-performance-vfd/customizable-install-simple-2-2kw-dc-to.html

J Tiers
02-06-2018, 04:32 PM
Half a second is pretty fast... try 5 sec. The displayed amps may not be the most recent number during accel.

The 3 HP motor with 2.2 kW VFD, is more motor than you have VFD. That means you have less power than you need, and while you may not need 3 HP, your motor will PULL POWER like a 3 HP when it is accelerating. You see this where the motor says 9A and the VFD says 7.4 (SVD PTS2.2GB)

Had to go out for a bit, back now (obviously)....

You can run a motor bigger than the VFD is intended for. But you usually cannot run it just as if it were the right size, because it is lower impedance than expected, and will have larger current surges on accel. That may also be why the vector etc did not quite work right, the values may be out of expected bounds.

Do a slower accel, so that the difference between commanded and actual frequency is not so large. That may keep down the current sufficiently.

Your VFD has only 120% overcurrent (P series) for 60 sec, and 150% for 3 (three) seconds. That is lower than most VFDs, which usually have 150% for 30 to 60 sec at least, with some having 200% for a few seconds in addition. With the low current limit, you must keep the surges low, and one way is to set for a slower accel. *

I note that "LaPond" is in Shenzen, China. I also note that the unit has similarities to the "Huanyang" units. Might be the same folks under a different name (they seem to have used several). While they may have improved, if they are the same company, the "Huanyang" did not have a great reputation.

I am not saying that to knock the unit. I don't KNOW enough about the unit to have an opinion. Just wondering if there is any relation.

* In some cases, typically where there is a larger short term current limit, it actually works better at a medium fast acceleration. That is because any faster goes over limit, while slower stays at high current too long, and trips on the time limit, even though it has not gone over the actual max current.

In your case, I very much suspect the "Torque limit" feature is preventing you from seeing an actual current limit situation. If you turn that off (assuming that is possible, see manual), then we may see if you are getting an overcurrent, even though it is not registering on the display.

Mister ED
02-06-2018, 07:04 PM
I am confused at which VFD you have. But looking at their specs, the biggest 1ph input VFD they have is 7.4A output rated at 2hp motor. The VFD that is rated at 9A, 3hp is actually a 220v three phase input VFD.
http://bbs.homeshopmachinist.net/attachment.php?attachmentid=2311&d=1517962115

J Tiers
02-06-2018, 08:05 PM
I am confused at which VFD you have. But looking at their specs, the biggest 1ph input VFD they have is 7.4A output rated at 2hp motor. The VFD that is rated at 9A, 3hp is actually a 220v three phase input VFD.
......

That is from the single phase input, which I am assuming he has..... since it is at his house and he is in Canada. It is pre-derated. Look at the INPUT currents for the two, the single phase is higher (although not by as much as one would expect)

That is also what made me think of Huanyang, which has a similar issue.

garyhlucas
02-06-2018, 08:16 PM
The VFD looks to be quite undersized. Just as reference we use a WJ200 Hitachi 2.2 Kw VFD on 240vac single phase to run a 4 hp motor continuously at about 1 hp actual power output driving a pump, 24/7/365 with no issues. Once in a while we do cleanings and run full 2.2Kw for about 5 hours continuously, again no problem. We know how much power we are using because the Hitachi has a Kw output as one of its very nice features.

Mister ED
02-06-2018, 08:45 PM
That is from the single phase input, which I am assuming he has..... since it is at his house and he is in Canada. It is pre-derated.

I was thinking maybe he had somehow ordered the 3ph unit, since that was the only one in the list with the specs that he quoted. Using that on 1ph would automatically derate it as well, right?

However, digging on the Amazon site a little more, I did find the following. So apparently this model is not listed in the model list from the other link.


Model: SVD-PS2.2B
Power: 3HP 2.2KW 220V
Input: 1PH AC220Vą15%
Output: 3PH AC0-220V 9.7A 0-500HZ
VFD size:16.5*12.5*19 CM/6.5*4.9*7.5 IN (L*W*H)

Got that new 50hz motor for my mill (that I was asking about last week) ... I think I will be sticking with the TECO vfd.

J Tiers
02-06-2018, 08:55 PM
I was thinking maybe he had somehow ordered the 3ph unit, since that was the only one in the list with the specs that he quoted. Using that on 1ph would automatically derate it as well, right?

However, digging on the Amazon site a little more, I did find the following. So apparently this model is not listed in the model list from the other link.



Got that new 50hz motor for my mill (that I was asking about last week) ... I think I will be sticking with the TECO vfd.

Eh, OK, a non-listed model. I did not look at the specs there on Amazon, but went for the table. And I checked to see if the overload percent worked out to 1.7A, it does not, at least not based on the 7.4A.

If it WILL do 9.7A, it should drive the motor. But the rest of it is the same..... he seems to be getting "torque limiting", so there is a current issue even so. PS models have 120% 1 min, 150% 3 seconds. Most others are 150%1 min, and some are 200% 3 sec in addition.

So if it draws over about 11.4A, which is perfectly possible with a high inertia load, and a faster accel, it will limit. I still think he needs to turn the torque limit off and see if he gets a fault code. The torque limit is holding the current lower and AVOIDING a "trip".

And that is ANOTHER point..... WHat is the limit set for the torque limiter? Torque is basically current, so it is a current limit, and may have its OWN setting. That needs looked into.

Matt F
02-06-2018, 09:20 PM
Folks, you are awesome! Should have posted up my questions earlier!

Yes, looks like the model was not in that manufactures link, I see that now.

This is the closest thing I can find to it on the manufactures site...

http://www.soyan-tech.com/variable-frequency-drive-vfd/solar-pump-ac-drive/vfd-variable-frequency-drive-pumps-3-phase.html



The plate on MY VFD (whatever it may be) clearly states,

model: SVD-PS2.2B
power: 2.2 kw 220V
Input: 1 ph AC220 +- 15% 23A
output: 3 PH ACO-220V 9.6A 0-600hz.

I thought the 9.6 amp would be enough for the 3 hp motor.

Here is another link with the model and more details.

https://crazyibuy.com/lathes/variable-speed-lathe/lapond-new-series-vfd-inverter-vfd-drive-2-2kw-220v-3hp-9-6avariable-frequency-drive-for-motor-speed-control-2-2kw/

Info from there below

Parameter

Model: SVD-PS2.2B
Power: 2.2KW 220V
Input: 1PH AC220Vą15%
Output: 3PH AC0-220V 9.7A 0-600HZ
VFD size:16.5*12.5*19 CM/6.5*4.9*7.5 IN (L*W*H)
Package include: 1xVFD;1x English User Manual book;6 x wiring terminal.
Item Manufacture:We are the original manufacturer more than 10 years.

Features

1.High startup torque 150%@0.5Hz 180% @0Hz (CLVC).
2.Excellent speed stability +/-0.5% (SFVC), +/-0.02%(CLVC).
3.Power Dip ride through.
4.Strong overload capability : 60s for 150% , 3s for 180% overload.
5.Rich of AI & I/O port, RS485 communication port, well work with Mach3 controller.
6.All-new sensorless flux vector control(SFVC) algorithm that gives better low-speed stability,enhanced low-frequency loading capacity.
7.Supports various encoders such as differential encoder,open-collector encoder,resolver and UVW encoder.
8.Supports three control modes,sensorless vector control(SVC),closed-loop vector control(CLVC) and V/F control.
9.With perfect error protection and short circuit starting protection capability.

I did play with a "torque boost" setting, but that was early on. I will look for a torque limit side too.

My current measurements were made with a stand alone clamp on the wires. I will look to see what the vfd says it thinks it is putting out ;)

Again, thanks for all the info!

Matt

Matt F
02-06-2018, 10:41 PM
one more thought/question.

I assumed in the V/F mode the torque limits/torque boost would be non functional??? and it would behave just as linear increase in voltage and frequency. I'm not sure I have actually tried adjusting those settings while in the V/F mode...

I will report back!

Matt

J Tiers
02-06-2018, 10:59 PM
I think it will work the same.

MattiJ
02-07-2018, 01:29 AM
Sounds like your vfd doesn't like the increased inertia at high gears.
Can you run the autotune on high gear?

AFAIK proper vector drive is rather complicated and computationally intensive.
How good the cheap china import vector controls are nowadays?

Btw. Yaskawa/omron 2.2kW V1000 should be around 300usd.. might be worth the extra bucks.