Question,
I have two 120w 12v electronic transformers and I want to combine them to create a 240w 12v transformer. As far as I’m aware I should be able to connect these in parallel and have this work.
Each transformer has a 110v hot and neutral, with two red (unpolarized) outputs at 12v.
By connecting each transformer to the same 110v input then combinging the two output leads (I would presumably have to determine the polarity on these). I should then be able to draw up to 240w.
Am I correct in this assumption, and is there anything about electronic transformers that could be damaged. It’s been a long time since I did electrical theory in school.
Thanks,
Replies
I'm not an electrician, but I'm having a hard time figuring out what you are trying to do, and an even harder time wondering why.
Are you mixing up your w's and v's? You seem to use them interchangably.
If it's 24 Volts that you are looking for, I believe you would have to connect two 12 Volt sources in series, not parallel; and no, I don't think transformers will work in this case.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
It is hard to say.
"Electronic Transformers" are really switching power supplies. And there are a gazillon different designs. Some sample the output voltage and use that to control the switching rate or duty cycle to maintain a constant output.
If they do have such feedback it is well possible for them to interact and do things like one of then shuts down or the the outputs voltage starts swinging.
The technical answer is to "try it and report back if you are able".
What is the application?
electronic XFMRs .....which are designed to be used near or in a single fixture......
won't work well as a large LV loop.
better to use multilpe runs from BOTH instead and keep them very short and as close to the source as possible
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'Wer ist jetzt der Idiot?'
Edited 4/18/2006 9:24 pm by maddog3
What are you trying to run with these "switching power supplies"??
20 amps at 12 v is a fair load...Is the output of the power supply ac or dc???
Bud
You have to hook them together in the proper phase. Connect the 120V sides as you intend, then connect only two of the output wires (one from each transformer) together. Measure the voltage across the other two. It should either be 24V (more or less, depending on meter type) or near zero. If it's 24 then you have the wrong two wires connected together -- swap ONE of the wires to be the other one from the transformer output.
Now you should have a measurement "near zero". If it's so close to zero that you can hardly measure anything. If so then you're good to go -- you can connect the two free wires and you'll have your 240W (well, probably should derate to 200W since the load isn't guaranteed to be perfectly balanced).
If, however, you measure something then the two transformers aren't identical. If they're sufficiently non-identical then there's a danger that current will flow "backwards" through one and the whole mess will self-destruct. Can't say how much out of balance they have to be for this to happen, but you're probably OK if there's less than a volt difference, and probably doomed if there's more than 5 volts difference.
PS: I'm assuming that "electronic transformer" simply means "transformer for use in electronic equipment", and that these are standard ferromagnetic transformers.
A lot of the supplies used with LV lighting use so called "electronic transformers". which are in fact just switching power supplies.If you look the specs on dimmers from Lutron and the like you will find ones speced for operation with line voltage loads, one spec to supply magentic transformers, and ones speced to supply electronic transformers.
Right. I explained my assumption. You shouldn't attempt to connect two switching regulators together without some real engineering.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
The application is low voltage track lighting.
The tracks were wired with a 120w transformer on the basis that the client would be putting 2 50w 12v lamps on each track. This has proved to be insufficient for the space and we now want to place 4 lamps of 50w each.
The transformers are on the job, so I do not have the specs in front of me but they were purchased from my local electrical distrubutor and sold exactly for this purpose, if that helps to define exactly what type of transformer they are.
Thanks,
If they are really electronic "transformers" (switching regulators) then don't try to parallel them unless you have mfr's specs for doing so. It may be possible, but it depends on the design.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
even if you manage to wire these things together, you won't be able to check the voltage without a load on them .....and then you need a meter that can read in the 20,000Hz range or better !>.........they were purchased from my local electrical distrubutor and sold exactly for this purpose, if that helps to define exactly what type of..........<not any more,.
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'Wer ist jetzt der Idiot?'
Would it be possible to just add a second track for the additional fixtures?
Liability comes to mind here. If you do combine the power supplys, and they are not explicity designed to do that, whether they "work" or not, and the client house burnt down, you can loose your drawers. Cheap insurance to do it right the first time.
The other thing you will have to take into consideration is that you will be pulling 20 amps or so thru the wires...if its 110v or 12v it makes no difference. 12v at 20amps is gonna take at least #12 wire.
Bud