Thread: VFD error
It might be worth a look inside, rubber gloves and extreme care around the caps though!
I've always regarded VFDs as a "Black Box" solution but when I recently had an unexplained bang/flash incident with a 750W Siemens inverter drive which then presented errors I decided it was worth a look.
When I stripped it I found a flexible power link between two internal boards had blown but the motor metered out fine and there were no wiring faults or other visible signs of shorts or damage, it had been running for months without any problem before it blew so I assumed the fused power link was a symptom rather than the fault but in desperation I made & fitted a new link and it's been working fine ever since,
I know it may seem obvious.
But i would not recommend opening the VDF for a good 30min after it has been powered to allow any caps to discharge.... apartr from that, it should not be to hard to identify blown componants, or indeed, vaporised earth connections. If i can not spot blown componats, i usually smell them or listen carefully when switched on.
Last edited by george uk; 20-05-2014 at 01:48 PM. Reason: adding stuff
Thanks for all the comments and advice. I'm away from the workshop for about a week so time to think about next steps.
Yes, plug is a GX16-3 and 2 of the female pins were worn away at the split line but not burnt as far as i could see. I suspect the continuous movement had worn them and eventually caused a spark.
I'll also check the cable when I get back and look inside the vfd
Starting to research new vfd and spindle. Any views on whether 3kW spindle is worth going for over the 2.2 to give more torque at low speed?
No problem getting a higher rated VFD than you need, within reason.
If you need the extra torque from the 3kW spindle then clearly get it...
Agree with Jonathan's post, here's a supplier I find very good Inverter Drive Supermarket - Variable Speed Drives for Electric Motor Speed ControlSpelling mistakes are not intentional, I only seem to see them some time after I've posted
Ok, I've had a look inside and nothing is visibly burnt or smalls burnt (although it was over week ago that the fault occured).
I checked continuity between UVW terminals and there is no connection between them. I didn't have time to do any more investigation but have today made contact with a VFD sales and repair company. They are offering a free quote if I can arrange postage to them, which is fair enough.
Don't know how much the repair will be yet. If it is less then £100 then I'll just repair it. If it around £100 (similar to a new Huanyang VFD), I'll have to think about which way to go. If it is £150 or over then it will most likely be the Chinese VFD and fingers crossed.
I know the risks with these units and the most popular 2.2kW unit seems to be the HY02D223B. I also noticed that they make a SL-222EE model which shows Vector Control Drive as a feature, and has also been shown with an optional removable front keypad panel and connecting cable. This panel can also have a pot added to it to manually control the speed. This would make it the same as my Moeller drive for which I was about to mount the keypad in the control box door. Anyone bought and used one of these models with the Chinese spindles?
I have found a long post from kajuk:
but he was having alot of set up problems despite Eddy's extensive suggestions for help.
As far as I can tell the spindle is OK. Checking resistance between pairs of pins shows about 2.2ohms. Does this seem about right? I know this is no guarantee of not having a short under actual load, but I'm willing to keep it for now and just fix or replace the VFD.
Finally I need to make sure that the cable does not spark again. I like Ian's idea of going direct so am looking into a gland/strain relief unit like this:
Spiral Cable Gland Strain Relief 4-8mm M16 Thread | eBay
I would remove the GX16 socket from the spindle end cap and wire the VFD cable direct to the motor, with an earth tapping made on the inside of the end cap. Might need to open out the GX16 socket hole, or better still tap it to suit the gland thread, but that should be no problem. What other neat cable solutions have others tried? Or are you still using the dodgy GX16-3!?
Check the resistance between each of the UVW terminals and the DC bus, as if just one is short circuited you'll still measure a high resistance between the phase connections.
I wouldn't worry so much about the Chinese VFDs - how many recent threads have you seen where the VFD hasn't worked, due to the product not the user? Also adding a potentiometer to either isn't difficult, so I wouldn't make a decision based on that.
2.2 ohms sounds about right for the DC resistance.
Edit: Also, regarding whether to get vector controlled or not - with vector control you will get more torque from the motor (at mid-low speed) and better efficiency, but if you're currently happy with the torque from the motor then it's not really gaining anything so you might as well go for the cheaper option.
Last edited by Jonathan; 29-05-2014 at 10:18 PM. Reason: Spelling
Thank you Jonathan. Here are some pictures for reference:
Are the IGBTs the 3 pin components with a small heat sink? I was vaguely expecting 4 pins but am no expert.
To get to the DC bus I guess I need to get to one of the big capacitor pins? There are 2 boards stacked on top of each other with the top one looking like the high power side and the bottom one looking like the control/software side.
It looks like quite a job to take the top board off to get to the pins since they've soldered multiple pins in place around the edge of the boards to hold it in place (or prevent tampering !).
I'll have another look, but most likely going to send it away.
Found this article quite useful . . . .
The ABCs (and 1-2-3s) of variable frequency drives | Motors/Drives content from Machine Design
The IGBTs will either be 3-pin components (6 of them - like in the picture you linked to), or a single module containing all 6. Either way they'll attached to the main heatsink as they are the components that switch the power through the motor, so have the highest losses in the driver. I don't think you can see them in your images, as they're probably on the lower PCB.
Yes - the capacitors are connected to the DC bus so if you can get to both pins of a capacitor, that's the same thing. They seem to have missed out one capacitor on the top PCB (the big circle), so you can connect your meter to those pads. The capacitors say 400V on them, so they will all be in parallel.
The 3-pin component in the 2nd picture is some sort of MOSFET to make a switching power supply - it's probably connected to the yellow inductor to derive the logic supply from the DC-bus.
Had no time yet again this weekend to look at this, plus the VFD sales and repair company seems to have lost interest.
So, finally decided on a new Huangyang 2.2kW VFD (HY02D223B). There are lots of these on ebay shipped from Portsmouth at £100.07 inc delivery etc. So has anyone had any dealings with these companies for example, especially returning any faulty ones or other good service:
Or any other Portsmouth import trader suggestions?
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