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

Tue Apr 12 17:11:49 CDT 2016

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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