[TriEmbed] Inexpensive 120V (15A) to 240V (7.5A) transformer?

Robert Gasiorowski rgresume at gmail.com
Tue Apr 12 17:25:14 CDT 2016


There's nothing about current or wire diameter, so I am assuming that 2kW
one can handle 16A (115V/32A in and 230V/16A out.)
You may want to confirm with the manufacturer (16A or ~2.5mm windings,) but
they look good to me.


On Tue, Apr 12, 2016 at 6:11 PM, Shane Trent <shanedtrent at gmail.com> wrote:

> Robert,
>
> I am leaning toward a Hammond 170J. This is a 2000VA model that appears to
> have 3 leads. I can set the input power limit on the inverter/charger to
> specify a maximum load on the 230V output side. Any concerns or
> recommendations for an output current limit?
>
> http://www.alliedelec.com/hammond-manufacturing-transformers-170j/70180833/
>
> http://www.alliedelec.com/images/products/datasheets/bm/HAMMOND_MFG/70180829.pdf
>
> Shane
>
>
> On Tue, Apr 12, 2016 at 5:07 PM Robert Gasiorowski <rgresume at gmail.com>
> wrote:
>
>> Shane,
>> you will need either transformer with two 120V primaries or one 120V
>> primary and one 120V secondary.
>> The windings must be no less than 8A (there will be losses) and have
>> power capacity of at least 1kW (900W in theory.)
>>
>> If you have an old 2kW+ APC UPS, you will find a nice, heft trafo inside
>> that you might be able to use for this.
>>
>> See attached
>>
>>
>>
>> On Tue, Apr 12, 2016 at 9:28 AM, Shane Trent <shanedtrent at gmail.com>
>> wrote:
>>
>>> Robert,
>>>
>>> I am leaning toward an autotransformer. I am trying to bump a 120V AC
>>> generator output up to 240V for an inverter/charger that has a split-phase
>>> 240V input. I have never worked with auto transformers so I was not sure
>>> how to view the current handling.
>>>
>>> Shane
>>>
>>> On Tue, Apr 12, 2016 at 8:55 AM Robert Gasiorowski via TriEmbed <
>>> triembed at triembed.org> wrote:
>>>
>>>> Get any 240V, 1kW transformer with dual primary (2 x 120V.)
>>>> Make one side common, connect center to 120V, the second side will give
>>>> you 240V (non-isolated.)
>>>> You will end up with what's called autotransformer. ATs are much
>>>> smaller than isolating transformers.
>>>> I used this type of transformers to power US made appliances like
>>>> microwave ovens in EU (220V->110V.)
>>>>
>>>> On Tue, Apr 12, 2016 at 6:45 AM, Josh Wyatt via TriEmbed <
>>>> triembed at triembed.org> wrote:
>>>>
>>>>> What are your power requirements?
>>>>>
>>>>> A few ideas...
>>>>>
>>>>> 1. If all you need is high voltage DC for charging a battery bank, you
>>>>> could use a voltage doubler. Check out the full wave circuit here:
>>>>> http://www.daenotes.com/electronics/devices-circuits/voltage-multipler
>>>>>
>>>>> 2. You could buy two identical 120vac-to-12vac transformers and use
>>>>> one for boost. Connect transformer 1 in the conventional way, to provide
>>>>> 12vac. Connect the 12vac output of transformer 1 to the 12vac winding of
>>>>> transformer 2; the "output" of transformer 2 will now have 120vac which you
>>>>> can place in series with your line voltage for 240vac. (make sure it's in
>>>>> phase or you'll get 0 volts out).
>>>>>
>>>>> 3. Alternatively, search ebay for 'control transformer,' as this is a
>>>>> pretty common need and application in the electrical world. Be sure to
>>>>> choose it properly for the voltages and power you expect. For example,
>>>>> http://www.ebay.com/itm/Square-D-9070T150D1-Industrial-Control-Transformer-SCHNEIDER-ELECTRIC-/272208984055
>>>>>
>>>>> Lastly - It goes without saying, but be careful; you're dealing with
>>>>> lethal voltages here.
>>>>>
>>>>> Thanks,
>>>>> Josh
>>>>>
>>>>> On Mon, Apr 11, 2016 at 11:14 PM, Kevin Schilf via TriEmbed <
>>>>> triembed at triembed.org> wrote:
>>>>>
>>>>>> Hi Phil,
>>>>>>
>>>>>> I don't know what Shane has in mind, but that is an interesting idea
>>>>>> about using two receptacles; although, Mr. Murphy will probably ensure that
>>>>>> opposite phase receptacles will be several feet apart as you note.  :-)
>>>>>>
>>>>>> Why not just add a two pole, 240V circuit breaker assuming you have
>>>>>> space in the panel and can reasonably run wire from your load to the panel?
>>>>>>
>>>>>> BTW, I think there may be a typo in your email, should be:
>>>>>>
>>>>>> AWG 10 -> 30 A
>>>>>> AWG 12 -> 20 A
>>>>>> AWG 14 -> 15 A
>>>>>>
>>>>>> To anyone reading this post, same impedance at twice the voltage = 4
>>>>>> times the power delivered.  Please be careful and consult a licensed
>>>>>> electrician if in doubt.
>>>>>>
>>>>>> Sincerely,
>>>>>> Kevin Schilf
>>>>>>
>>>>>> ------------------------------
>>>>>> *From:* Phil Smith via TriEmbed <triembed at triembed.org>
>>>>>> *To:* Shane Trent <shanedtrent at gmail.com>; TriEmbed Discussion <
>>>>>> triembed at triembed.org>
>>>>>> *Sent:* Monday, April 11, 2016 6:59 PM
>>>>>> *Subject:* Re: [TriEmbed] Inexpensive 120V (15A) to 240V (7.5A)
>>>>>> transformer?
>>>>>>
>>>>>> If you can find outlets close to each other whose hots (x and y) are
>>>>>> from adjacent circuit breakers, then you could combine x,y, and g (ground)
>>>>>> using two plugs to get 240V, although the outlets are likely only rated at
>>>>>> 120V, 15A (14 AWG wire).  Another way of looking at it is x=+120V, y=-120V
>>>>>> (relative to Neutral n here n ~= g except at high current draw.  Often
>>>>>> wiring within a single residential room is from a single circuit breaker.
>>>>>> Interestingly, the National Electric Code (NEC) rates 10, 12, and 14 AWG
>>>>>> wire at 15,20, and 30 amps no matter how long the wire is, analogous to the
>>>>>> state of SC once legisilating the value of pi to be exactly three.  AWG<10
>>>>>> wire is not subject to this arbitrary amperage and equations for resistance
>>>>>> and reactance are used instead.
>>>>>>
>>>>>> Phil
>>>>>>
>>>>>>
>>>>>> On Monday, April 11, 2016 5:16 PM, Shane Trent via TriEmbed <
>>>>>> triembed at triembed.org> wrote:
>>>>>>
>>>>>>
>>>>>> Hey all!
>>>>>>
>>>>>> I am looking for a transformer to setup 120V up to 240V. I recall
>>>>>> seeing a transformer company at the Hamfest last year but do not remember
>>>>>> the name. Can anyone recommend a vendor? Does not have to be a high-end
>>>>>> design. Is powering a charging system that corrects for variations in line
>>>>>> voltage.
>>>>>>
>>>>>> Thanks for any suggestions!
>>>>>>
>>>>>> Shane
>>>>>>
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>>>>>>
>>>>>>
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>>>>>>
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>>>>>>
>>>>>
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