First CNC build - VFD wiring question
Hi All,
Fingers crossed I have put this thread in the right place - apologies if not..
I recently stumbled across this forum, not sure how I missed it up until now but that's another story lol
Anyway to cut to the chase I started building my first CNC towards the end of last year, as is normally the way things set me back and other projects took all my time up. On the proside I how have it 95% wired up and motion control is working a treat. All I'm left with is the VFD.
Now I'm sure this is a pretty basic/stupid question but here goes:
Am I correct in thinking the VFD (2.2kw) can be powered directly from the plug socket (via an isolator)? Or does it have to be wired via a separate power source?
I just don't want to plug it in and blow it up within seconds,
Many thanks in advance.
Bez
Re: First CNC build - VFD wiring question
There was a discussion about this a little while ago. Simple answer is to stick a 13A plug on it and plug it in the nearest socket - no problem.
Re: First CNC build - VFD wiring question
According to the manual my 2.2kW inverter can take up to 21 amps on the input but that allows for overcurrent. I have the max amps set to 17.6 A.
It's only because we don't run them flat out that a plug works.
Re: First CNC build - VFD wiring question
Quote:
Originally Posted by
EddyCurrent
According to the manual my 2.2kW inverter can take up to 21 amps on the input but that allows for overcurrent. I have the max amps set to 17.6 A.
It's only because we don't run them flat out that a plug works.
Eddy You can plug a 3kw dryer into a 13A socket or washing machine. So I think 2.2Kw is no problem ..Clive
Re: First CNC build - VFD wiring question
Clive a dryer is mainly a resistive load rather than a reactive load as an inverter is...so its not quite as simple as that
Re: First CNC build - VFD wiring question
Quote:
Originally Posted by
Clive S
Eddy You can plug a 3kw dryer into a 13A socket or washing machine. So I think 2.2Kw is no problem ..Clive
I only said the manual states it can take 21 amps input, I can't argue with what the manual says.
You need to multiply three phase amps by sqrt 3 to get single phase amps.
2.2 kW 3 phase motor amps = 9.5 A, single phase input amps 9.5 * 1.73 = 16.45 A
Re: First CNC build - VFD wiring question
I think that Eddy has already pointed out that the inverter manual takes into account over-current. Not sure what that inverter is rated at, but I use a 5KW inverter on my lathe which is rated at something like a few seconds at 100% overload and 30 sec at 50% overload. I think that this is probably to allow for motor run-up initial surge, although I'm not driving it that hard. However, let's say max load for a normal Chinese VFD/spindle combination is a nominal 2.2KW, and allowing for conversion inefficiency, that's going to draw maybe 2.5KW from the supply. That's about 10A. Short-term permitted overload is about twice that, which neatly comes out to about 20A - which is where we started!
In real life, though, I would suggest that there are two possible times when the inverter is likely to trip the supply fuse/breaker. One is when you first switch it on. These devices typically rectify the incoming single-phase supply to give a DC supply internally which then drives the 3-phase output generator. There will be a small surge at that time which can give problems. Sometimes the problem is due to funny phase relationships between input current and voltage which can trip RCDs. However, my limited experience with my 2.2KW inverter is that this never happens (although it is a problem for the big inverter I use). Second time it might trip is when the load comes on, i.e. motor startup. However, the inverter is generally set to soft-start the motor - ramp up speed over a few seconds - and that keeps the peak load down. Anyway, you will be spinning up a motor when it is not cutting, so that reduces the load as well.
Upshot of all this in practical terms - it works fine for typical router purposes off a standard 13A socket!
1 Attachment(s)
Re: First CNC build - VFD wiring question
Cheers for the replies guys :)
Looking through the manual it states its output current at 10A. Its not a fancy VFD just a huflugdung (Huanyeng) special bought from here http://www.cnc4you.co.uk/Spindle/Spi...h-Matching-VFD.
13A plug sounds like a winner to me but I will obviously be careful with other items running on the same ring until I can figure out its own ring for it to sit on.
So looking under the front panel I'm faced with this:
http://www.mycncuk.com/attachment.ph...id=14673&stc=1
Motor wires are self explanatory so no need to go over those. Where I'm a bit confused is R S T ...... does it matter which one the live and neutral go to? Obviously the earth goes to "9"
I'm using a KK01 breakout board which has a relay output ..... am I correct in thinking this can be used to start and stop the spindle. If so which would be the correct blocks to wire it into from the basic mention in the manual DCM looks like it might be the one but rather than mess things up I'd appreciate any input for people who have run or are running a similar setup.
Thanks again.
Re: First CNC build - VFD wiring question
Mains input is easy - just use two out of RST, and it doesn't matter which one is live and which is neutral.
Can't help off-hand with the spindle switching as I don't use it at the moment. One day I'll get round to proper spindle speed and on/off control, but I'm not there yet! For the time being, I just use the front panel controls.
1 Attachment(s)
Re: First CNC build - VFD wiring question
Here's what came with mine, should be of some help...
Re: First CNC build - VFD wiring question
Nice one :) I like pictures like that ....... its like painting by numbers lol
Re: First CNC build - VFD wiring question
Thanks for your help guys its all up and running now :)
Re: First CNC build - VFD wiring question
Hi guys,
I just bought the KKO1 BOB, I'm trying to to hook it up to the DIYCNC spindle board and then onto the VFD so i can have Mach 3 Control. I would also like to use the spare relay from the KK01 for on/off of a vacuum table lets say. Is any one able to confirm the wiring it correct. I really don't want to blow up any more components. the two links below are for the manuals. many thanks
http://s13.postimg.cc/rix1k49xz/KK0...VFD_hookup.jpg
pic host
https://www.mediafire.com/?rc61wkf8r4m4or6
https://www.mediafire.com/?rc61wkf8r4m4or6
2 Attachment(s)
Re: First CNC build - VFD wiring question
Quote:
Originally Posted by
rbs
Hold on ! Looks like you are switching the spindle on and off at the mains input to control it. If you want to start and stop the spindle this is not a good idea! Leave the VFD powered directly from the mains all the time and control it using the green inputs on the control panel - the row of small terminals above the mains and spindle connections.
Attachment 14818
Here is the schematic:
Attachment 14817
This is how I think it should work:
Start / stop = connect relay terminals to FOR and DCM. The relay makes or breaks this circuit.
To get this to work you also need to set PD001 to 1 (from memory) to tell it to use this external control.
Speed control (manual) = connect a 3 pin potentiometer (say 10k) with one outer pin to VR, the opposite pin to ACM, and the middle pin to V1.
To get this to work you also need to set PD002 to 1, and set the little jumper (on the right side of the green input panel) to VI to tell it to use the external control
Speed control (auto with voltage control) = connect 10V from BoB to V1 (as you have drawn it), and 0V to ACM (not as you have drawn it to A1 which is for current control and it looks like your BoB is outputing a variable voltage)
Re: First CNC build - VFD wiring question
Hi OK, thanks for that and the extra info.
for the interest of this thread I've redone the schematic just so there's no one else following committing to fry their electronics.
Does this look correct? Many thanks
http://s12.postimg.cc/rppfv2arx/image.jpg
free image uploading
Re: First CNC build - VFD wiring question
Quote:
Originally Posted by
rbs
Hi rbs
Your new sketch still looks wrong on the speed control part. If the spindle control board is putting out a variable 0-10V to control the speed then in my view:
+ on the board should go to VI on the VFD
- on the board should go to ACM on the VFD
Don't connect anything to VR or AI for what you are trying to do.
Also, note that the manual shows a grounded shielded cable for the control cable (the dotted hoop around the input lines) to reduce interference.
*If any moderators are reading this it is probably more appropriate to move it to the electronics > VFD section . . .*
