Author Topic: Looking for a large step-down transformer (Read 1939 times)

craig110 · « **on:** January 21, 2007, 06:25:54 PM »

I'm looking for a naked 2:1 stepdown transformer (110/120v -> 55/60v) that can handle about 20-30 amps on the output side. ("Naked" meaning just the core and windings; no controllers, no yada yada.) When I search, I'm only seeing smaller wattage transformers or else units designed to convert 220v to 110v voltage for travelers. (The latter I could use, of course, except that they come with voltage regulators and packaging that I'd have to rip out for my use.) Does anyone have a good source of transformers that would fit my need? Thanks!

Craig

Ungrounded Lightning Rod · « **Reply #1 on:** January 21, 2007, 11:31:48 AM »

What are you planning to use it for? If it's for a mill, rather than line power, you may need to convert the voltage ratings to compensate for lower frequency.

craig110 · « **Reply #2 on:** January 21, 2007, 11:43:34 AM »

Its for line power.

Nando · « **Reply #3 on:** January 21, 2007, 12:22:14 PM »

Craig:

It would be much better that you detail what you want to do, to assist you better if that is the case.

Inform and you may get "brilliant" suggestions for your "secret" project -- so "UN-secret it"

Nando

TAH · « **Reply #4 on:** January 21, 2007, 12:45:45 PM »

A transformer like this will weigh quite a bit. If you don't mind paying the shipping I could sell you one.

veewee77 · « **Reply #5 on:** January 21, 2007, 12:50:05 PM »

Easy way. . . find a 48V golf cart charger. Those likely put out about 55-60V on the secondary, unloaded.

Doug

Dennisd · « **Reply #6 on:** January 21, 2007, 01:11:42 PM »

Industrial electrical warehouses normally (in N.A.) stock transformers with 2:1 or 4:1 step down ratios. A rating of 480/240 to 240/120 will allow you to configure it as a 2:1 step down, both sets of coils in parallel, with 110V on the input, you will get 55V on the output. these are available from small 50Va control transformers up to unbelievably big. I use a 3KVa unit to convert my 120V inverter output to 240 for the existing house loads. If using for a variable frequency application, derate them (ie: buy a bigger size).These transformers are just copper and laminates.

Dennis

craig110 · « **Reply #7 on:** January 21, 2007, 02:03:50 PM »

PM sent.

craig110 · « **Reply #8 on:** January 21, 2007, 02:12:03 PM »

Thanks, this is one of the options that I'm looking into. I tried to snag one cheap on eBay, but the bidding is heading up.

craig110 · « **Reply #9 on:** January 21, 2007, 02:15:49 PM »

TAH,

Oops, my email to you bounced on an invalid recipient even with the "dot-swap" in your email address. What size transformer do you have and what would you want for it?

Craig

craig110 · « **Reply #10 on:** January 21, 2007, 02:39:52 PM »

Nando,

There is nothing secret about it, but I just didn't think that a detailed explanation was required to ask such a specific question. (It feels like going into a new grocery store and asking where the milk is, but before getting an answer you have to explain why you want milk.) But, since you're obviously curious, I'm adding a generator as a secondary backup to my grid-tied panels / battery backup. The most straightforward way of doing that without coupling the AC output of the generator to the inverter (which the manual says not to do with this model) is to have the generator charge the batteries. (And, as an aside, I'll configure things so that I can switch our furnace over to being fed by the generator which not only uses the generator's extra power but lets the batteries charge faster due to the lighter AC load through the inverter. That way, it should limit the need to run a noisy generator through the night.) I have a spare C40, so I don't need a full-blown 48 volt battery charger if I can get 55-60v DC cheaper through a transformer / rectifier setup.

Happy now that I've "UN-secreted" it?

Craig

Nando · « **Reply #11 on:** January 21, 2007, 03:02:52 PM »

As You can see, You "un-secret" it and You started to get the proper responses.

It is not curiosity, it is to insure that the proper information is available for you to get the proper responses.

Also, you can get a telecom battery charger, making sure it is not with a ferro-resonant transformer because the generator does not have an accurate 60 HZ frequency and ferro-resonants most do require an accuracy of 60 +/- 0.5 Hz.

Curiosity in this group is not for me to "enhance", there are many reasons for such statement, which I will not define.

Nando

craig110 · « **Reply #12 on:** January 21, 2007, 03:22:43 PM »

"As You can see, You "un-secret" it and You started to get the proper responses."

Ah, except all of these "proper responses," as you call them, came before I "un-secreted" my question. Take a look at the timestamps.

TAH · « **Reply #13 on:** January 21, 2007, 03:26:37 PM »

That email expired a while ago. you can use tom (@) rsixray.com

RP · « **Reply #14 on:** January 21, 2007, 04:34:55 PM »

As far as it goes, you asked for a transformer with 55-60v output. Rectified this is 77volts DC. Later you said you want 55-60volts DC. Which do you want?

craig110 · « **Reply #15 on:** January 21, 2007, 04:53:33 PM »

Any of the voltages would be fine. We get extended power outages so rarely that efficiency isn't really an issue. If the power outage looked like it was going to be really, really long and I wanted to conserve our gas supply, I could always connect its output to my MPPT controller instead of the excess C40.

Countryboy · « **Reply #16 on:** January 21, 2007, 11:39:02 PM »

It might be worthwhile to look at the transformers in an old Lincoln buzzbox welder. You might be able to adapt that to your need.

asheets · « **Reply #17 on:** January 22, 2007, 11:09:54 AM »

Not knowing anything about your particular load and wattage needs, I'd say that a couple of doorbell transformers would do the trick.

alibro · « **Reply #18 on:** January 22, 2007, 05:31:55 PM »

What about an old UPS. Lots of them have 48V batteries

News:

Author Topic: Looking for a large step-down transformer (Read 1939 times)