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Sizing Portable transformer for operating US 110V tools

Discussion in 'Electrics UK' started by Pumice, 10 Jun 2014.

  1. Pumice

    Pumice

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    Hello

    Need to run several American 110Volt tools on 220-240volt 50hz supply.
    What Kva rating transformer should I get?

    Below are list of tools:

    * Hilti TE-50 or TE-60

    120 Volt 60hz
    12.8 amps
    So that works out to about 1530watts (using an online wattage calculator)

    * Makita or DeWalt Miter saw
    120volts 60hz
    15 amps
    1800 watts

    * Makita steel cutting chop saw
    120 volts 60hz
    15 amps
    1800 watts.

    ---
    I understand that I need to oversize a transformer by about 40% of the max wattage a tool requires.

    So would a 3kva or 3.3kva site transformer be enough?
    What KVA rating transformer are used in the UK to run tools like the ones mentioned above?

    Will something like the below 3.3kva 16 amp Draper work fine for the Miter saws?
    NOTE: I only need to run 1 tool at a time.

    [​IMG]

    http://www.ebay.com/itm/MACHINE-TOO...t=UK_Hand_Tools_Equipment&hash=item2a363b99de

    Thanks[/b]
     
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  3. bernardgreen

    bernardgreen

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    Equipment designed for 60Hz is likely to take more than its rated current when operated on a 50Hz supply. The impedance at 50Hz will be less than than at 60Hz hence the extra current which will affect the rating of the transformer used.

    Yellow brick transformers may not be designed for continuous operation at full rated loading. Check the specification for time versus load safe areas.

    Induction motors will also run slower. Some brushed motors may run faster due to the lower impedance and higher current.
     
  4. ericmark

    ericmark

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    Much depends on motor type many are brushed and be it DC or AC never mind 50 or 60 Hz it does not matter so will be no problem running on 50 Hz but others use squirrel cage motors and these will run slow so need an inverter rather than simple transformer to correct the cycles.

    With our 110 volt transformers it is split phase (55-0-55) again in the main not a problem as most tools as all pole switching but again there are exceptions.

    Also the bricks (Yellow portable transformers) are a compromise balancing weight against efficiency so OK for short bursts but long use will cause over heating. The wall mounted are far better quality don't run as hot use less power and outlets normally protected.

    As to size again 13A is the normal outlet which is normally supplied with 32A MCB but in some cases down to 16A with the latter 2.2kW/kVA is about the limit you can use without tripping. The 13A fuse will normally take the inrush it's the MCB which often trips with inrush.

    With a B32 MCB feeding a 13A socket likely the one you have selected will work but personally I would use a smaller one so it will also work with a B16 MCB if it needs to be portable. If not portable then better with the larger wall mounted type. All of course dependent will your tools work on 50 Hz.
     
  5. Pumice

    Pumice

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    The above Draper has 3.3kva intermittent rating.
    Continuous rating is 60% of that, which is about 1.9kva.

    The most powerful tools are the miter saw and chop saw, both of which are rated at 15 amps (each) , so about 1800 watts. So I should be ok?

    Can I suffice with 15amp or 16amp output or do I need 32amp?

    The below 3.3kva Carrol & Meynell portable transformer is rated at 1.65kva continuous and output is 16 amp.
    http://carroll-meynell.com/products...ormers/portable-tool-transformer-cm33002.html

    Carrol & Meynell also make a US spec portable transformer that is 3.0kva continuous but it only has 15 amp output.
    http://carroll-meynell.com/products...rs/us-supply-autotransformer-cm3000-a-us.html
     
  6. Pumice

    Pumice

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    I checked with Hilti , they said 50hz not a problem. Don't think it's going to be an issue for Makita either but will call them.

    So 16 amp transformers are ok? I do not need 32 amps?
     
  7. Pumice

    Pumice

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    Any of you familiar with this type of portable transformer? They are made in China.

    [​IMG]

    Above is 3kva , intermittent I assume.
    There is a 5kva one also.
     
  8. flameport

    flameport

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    For 1 tool at a time, a standard 3.3kva yellow site transformer will be fine.
    They are all rated for intermittent use, but that is exactly what power tools are.
     
  9. Pumice

    Pumice

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    The Hilti combihammer te-60 will see continuous use for 10 minutes though cause I need it to do chipping.
     
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  11. ban-all-sheds

    ban-all-sheds

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    So you're going to be travelling from the USA to here, lugging around 50kg of power tools with you?

    If so they alone will blow your baggage allowance. Have you considered hiring tools over here?
     
  12. flameport

    flameport

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    Not an issue at all - only half the transformer rating anyway.

    The point is that vast numbers of similar rated power tools and transformers are used all over the country every day - they don't set on fire, blow up or do anything else they shouldn't.

    The transformers have a thermal cutout in anyway, so even if grossly overloaded with multiple high power tools left running continuously for hours, the worst that will happen is the cutout will operate and the power will be disconnected.
     
  13. ericmark

    ericmark

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    For continuous use the transformer will look like this [​IMG] however the yellow brick is used all over the place with very few problems.

    Our rules state we must use 110 on building sites so they are a common sight. The problem with the better quality transformer is they cost more to buy.
     
  14. ban-all-sheds

    ban-all-sheds

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    I bet they're fun to fix to a wall single-handed.
     
  15. winston1

    winston1

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    I suspect that is not a transformer, but an electronic voltage converter. Avoid.
    The yellow brick type 3.3 KVA is adequate for your needs.
     
  16. ericmark

    ericmark

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    Not bad you can remove the transformer while you fix the box then replace it. If you put an ammeter on supply to unloaded transformer you will see a huge difference between box on wall and yellow brick.
     
  17. ban-all-sheds

    ban-all-sheds

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    OOI what current does each type draw when unloaded?
     
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