Page 1 of 2 12 LastLast
  1. #1
    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 :)


    Many thanks

    Gary

  2. #2
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 1,005. Received thanks 170 times, giving thanks to others 5 times.
    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.

  3. #3
    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

  4. #4
    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.

  5. #5
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 1,005. Received thanks 170 times, giving thanks to others 5 times.
    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).

  6. #6
    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.

  7. #7
    what thickness cable is the extension lead.

  8. #8
    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 11:19 PM.

  9. #9
    Quote Originally Posted by gary_808 View Post
    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.
    Yes you will be ok. Often the machines I build for people or help people with end up in sheds or Car garages running from an extension cable reel from house and very few have any issues. This includes Vfd and dust extraction, lights everything.

  10. #10
    Quote Originally Posted by JAZZCNC View Post
    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.
    If the spindle is stalled and drawing rated, or even higher, current from the VFD, that's actually requires very little power from the mains. One way to think of it is to recall that power is the product of torque and speed, so when the spindle is stalled the speed is zero so the mechanical power required to apply rated (or any) torque is also zero. From an electrical point of view, you still have to put current through the winding to get torque, but that current in this situation is only supplying the losses in the motor ... so the power, and thus current, drawn from the supply is low - I'd guess an amp or two at most.

    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.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

Page 1 of 2 12 LastLast

Similar Threads

  1. FOR SALE: power supply
    By Web Goblin in forum Items For Sale
    Replies: 0
    Last Post: 14-09-2014, 03:19 PM
  2. Replies: 0
    Last Post: 25-01-2012, 09:29 PM
  3. FOR SALE: 50V 20A Power supply
    By Jimmybristol in forum Items For Sale
    Replies: 8
    Last Post: 30-05-2011, 11:01 PM
  4. power supply problms
    By Scott in forum General Electronics
    Replies: 13
    Last Post: 11-07-2010, 12:58 PM
  5. power supply
    By hitmythumb in forum General Electronics
    Replies: 6
    Last Post: 21-06-2009, 10:27 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •