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Hi guys,
I have a vfd malfunction and some times I turn it on, it throws a spark. Few times, it stops after it has turned 1-3 times and I get a 'dl error' on the screen.
After I opened the board, I found a burnt object, which I attached. Can you tell me what is this object and its electronic characteristics in rder to find a replacement part?
Thanks in advance.
Hi,
"dl" means "overcurrent" for most chinese spindles.
The part may be a self resetting fuse - but without identification numbers it can be basically anything.
However: the blown part is most likely the result but not the cause of the problem. I'm quite sure that even if you manage to get a replacement it will blow again.
Check the spindle for shorts agains each phase and housing. This is however hard to impossible to to with a cheap multimeter - it is better to give it to someone with a proper insulation tester.
(and be careful with VFDs - they can kill you)
Christian
Hi, thanks for the quick reply.Quote:
Originally Posted by Christian Knüll
What do you mean by 'housing'?
The power wiring of the VFD to spindle is the following: I wired the U,V, and W VFD outputs to the 3 pins of the spindle and I left the pin 4 non-connected.
Could it be this the cause ?
Also the ground terminal of vfd has been connected to the ground from the wall.
Thanks again.
That appears to a MOV, Metal Oxide Varistor and is used for absorbing overvoltage or voltage spikes, the problem with them is if the absorb more energy than they are designed for they self destruct.
Hopefully there will be a number on it, otherwise you have to go by the normal or peak operating voltage across it, and the physical size for the energy value.
Al.
Hello,
Well, the spindles housing or "body" - basically the whole outside of the spindle...Quote:
Originally Posted by kostas1
No - but you're playing with your life if you just ground the VFD but not the spindle itself...Quote:
Originally Posted by kostas1
Again: VFDs can kill you - even if disconnected the input capacitors may still be charged to about 325V for a while.
I'd also not rely too much on things some guys tell you over the internet if you're not familiar with this kind of equipment.
Give both spindle and VFD to an electrician - he has the equipment to see what is defect and whether it makes sense to repair or not.
The part is most likely a varistor like Al_The_Man said.
Christian
So you suggest that I should also use the pin 4 of spindle and ground it using the ground pin of vfd?Quote:
Originally Posted by Christian Knüll
Thanks.
Unfortunately, it has no number on it. The voltage is 240V. I have o look for the manual. This is a chinese vfd so manual does not make sense some times.Quote:
Originally Posted by Al_The_Man
Yes the VFD earth ground should continue and ground the frame of the motor, some of the Chinese hi rpm have a four pin plug but the motor socket ground pin is open, you need to test it.
Al.
However this does not have to do with the burnt MOV, doesn't it?Quote:
Originally Posted by Al_The_Man
No, it was in answer to post #6.
Al.
So, do you guys know any way of knowing what are the characteristics of this part? I already contacted Chai from ebay and waiting for his answer.
Thanks.
There is a process as outlined in my old GE MOV Suppresion manual, (I see it is a collectors item now!).
If we assume it is in fact a MOV, there is a way of doing a conservative estimate, first the peak voltage the device should ever see in normal operation, either AC or DC has to be known and then what would be the max energy it has to dissipate which is usually unknown without measuring, but the where a device is being replaced, the physical size is a good indication, go slightly larger if anything, on the energy value.
In most circuits, the device will still operate OK without the MOV, as it normally only comes into play when a spike occurs.
If the device does NOT operate, it could be there are other defective components also.
If you Google Transient Voltage Suppression, you should get some articles that may help in selection.
Al.
Yes, it does operate and sometimes I get the 'dl error' in VFD's screen...So if the spikes are the enemy, why not buying a UPS which could also stabilize the input voltage and protect it from lightings etc?Quote:
Originally Posted by Al_The_Man
Thanks
That would protect the input supply, but there are switching transients that may occur on the motor/switching side?
You may be able to identify what stage the MOV is wired in?
Al.
What do you mean by 'stage' ?Quote:
Originally Posted by Al_The_Man
Thanks.
Before or in the DC supply supplied by the 1ph/3ph input, or on the motor output/switching side.
Al.