I mostly just read on here,
I've started collecting parts for my build mechanically I have my head round it all,
But electrically my main supply I'm struggling with,
obviously in the UK we have 220v 13amp supply in the house, I'm thinking this won't be enough to run a 2.2kw spindle/VFD inverter, my pc, main power supply for the steppers and a coolant setup.
Maybe I'll need to separate it out and split it between two sockets?
How is every one else doing it?
Also when I look at 2.2kw inverters single phase to 3 phase most advice an input current of between 16-20amps ? How are people running them on normal feeds?
Hopefully I don't sound to stupid :)
If you add all the power consumptions together, it will still be under the 3KW max you can reasonably draw from a 13A socket. The main reason people use a minimum of a 2.2KW spindle is because it takes ER20 collets which allow you to use up to 1/2" shank cutters. I doubt if there are many home-built machines that are strong enough to load these spindles to max power, so in practice you will be drawing much less and you will be even further under the max permissible for a 13A socket. Consider plugging the VFD into one socket and the rest of the electrics into another. Each will be way under max load, and behind the covers a normal UK ring circuit feeding them will be fused (MCB'ed?) at 30A which is plenty.
House consumer unit --> 32A RCD --> shed consumer unit --> 16A CB --> cnc machine (all electrics in one panel)
cnc PC fed from a 13A socket in shed.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Normally You won't have any trouble running everything off a single 13a circuit or socket even when spindle is under full load or even stalled pulling max amps. But if running direct from mains ring then you have to factor in any other electrical items that can affect and pull high loads. Ie Fridges, Kettles, emerson heaters etc.
It's not uncommon for machines running off domestic supplys to be work fine for months or years then for no apparent reason start locking or tripping breakers. (often it's PC that crashes first) 99% of time when this happens it's nothing to do with CNC machine or it's PC. It's a scaled up kettle or Fridge motor failing so pulling higher loads and the combination pushes the whole circuit over the edge or in most cases the PC PSU is sensitive to power drop and will shut down to protect it's self or lockup.
If your system is running on it's own 13A circuit ie for workshop then you won't have any troubles at all, even with a small/med compressor or dust extractor running.
One reason why you sometimes see higher ratings required for inverter power supplies is if they are designed to switch on at full load. The kinds of VFD/inverter you use with these spindles will ramp up relatively slowly, though, and that keeps the initial surge under control which might otherwise trip a breaker. My machine runs off a single 13A socket with VFD, PC, stepper drivers, etc, all running from that. The same ring supplies the wet-and-dry nominal 1200W vacuum cleaner for dust extraction, and I have never had a problem with any of that. The garage ring is separate from any of the house ring circuits, to avoid the kinds of problem that Jazz mentions (and the possibility of a problem with a machine in the garage tripping the house ring that feeds the television or my wife's sewing machine, which could lead to drastic loss of privileges).
Sound s promising! Cheers guys.
I won't be using the Chinese VFD as I've seen alot of people have issues.
I'm also planning on having a slower spindle as well, 6000 rpm with a 1.5hp motor and pulley drive, so I guess I keep the ramp up speed ill be just fine as that's what 1.1kw max.
Sadly I live in rented accommodation currently so can't go changing the wiring lol! But do have about a 2 metre extension to my shed from the house so should be fine.
what thickness cable is the extension lead.
Being only 2 metre I'd be fine on 1.5mm but I over engineered it incase, 2.5mm 3 core artic flex, I run my 180 amp welder off a 40 metre version i made up at work on advice of electrical dept, with no issues on full whack so assumed I'd be ok.
Last edited by gary_808; 31-01-2015 at 10:19 PM.
Assuming you're operating within the motor's continuous ratings, you can only draw a rated power from the supply when the motor is driving a load (be that a tool or just accelerating itself), at around rated speed. This is obvious when you consider that the cooling power of the water cooling system is limited, so for the input power to the system to be much higher than the cooling power there has to be a significant mechanical power draw, otherwise the motor would be fried as the extra power has to go somewhere.
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