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.
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.
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.
Last edited by EddyCurrent; 15-02-2015 at 02:45 PM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
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
Last edited by EddyCurrent; 15-02-2015 at 04:05 PM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
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!
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:
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.
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.
Here's what came with mine, should be of some help...
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