1. Home
  2. General Electronics
  3. Simple Transformer Question

Simple Transformer Question

Hi folks,

I've got a simple question that's probably very stupid, but I'll ask anyway: I've bought (on the cheap) a couple of basic transformers that were advertised as both 220V-110V and 110V-220V transformers, because I'd like to run some US electrical equipment over here (the Netherlands). These things didn't come with any documentation other than the labels, which proclaim the following:

Primary: 100V Secondary: 240V

50/60 Hz (I'm assuming 50 for the 110, 60 for the 220) 1500 watts

Does it matter which way 'round these get wired? Because they seem to be set up as step-up transformers for use in the US with 220V equipment. They're very basic steel boxes with stickers and two wires hangin' out the back end, one wired with a US-style grounded plug (need to get rid of that, and replace it with a strip of power sockets), and one

3-conductor wire ready to accept a grounded plug on the other end.

Any help for me?

Thanks,

Mattia

Reply to
Mattia Valente
Loading thread data ...

What comes out is the same frequency as what goes in.

Yes!

Iin one direction they step the supply voltage up by just over a factor or

  1. In the other they drop it down by the same factor. Get it wrong and you turn 230V into more than 500V !! That will damage your US equipment!
Reply to
CWatters

Ah. Is that going to mess with electrical equipment (power tools and heat blankets, as well as a small 'hot pot', ie a resistor with a thermostat on it, in this case), or doesn't that matter all too much?

Well, yeah, I meant will it work stepping down and up, regardless of what's labled 'primary' and 'secondary'. I know one end is for 110v equipment, and one's for the 220, and that plugging the 110 (stepped down) side into 220 is a recipe for disaster. I'm hopeless, but not THAT hopeless ;-)

Thanks!

Mattia

Reply to
Mattia Valente

--- You might have got them on the cheap because they're not quite what they were advertised to be. That is, if they have a 100V primary and a 240V secondary, then with 120V into the primary you'll get 288V, _not_ 240 out of the secondary, and if you connect the 240V secondary to 240V mains you'll get 100V, _not_ 120V out of the primary.

It matters _very much_ how you connect them to the mains, since if you connect the 100V primary to 240V mains not only will the voltage coming out of the secondary be 576V,(!) theres a good chance you could destroy the transformer or, at the very least, blow a fuse or open a breaker somewhere.

The 50/60Hz part means that they'll work on either 50 or 60Hz mains, regardless of the mains voltage, and the wattage (Volt-Amperes, really) means that the product of the transformer's output voltage and current can't exceed 1500. That is, if you've got the transformer connected to 240V mains and it's outputting 100V, whatever you've got plugged into it mustn't draw more than 15 amperes. (100V * 15A =

1500VA) If it's 120V that's coming out, that reduces to 12.5 amps.

-- John Fields

Reply to
John Fields

obviously you need to connect the 220 volt winding to 220 volts... to get 110 out

the transformer will work fine at either 50 or 60 hz and resistive component such as heaters or incadescent light bulbs will work fine at either frequency...

items such as synchronous motors found in some clocks and record players/ tape recorders etc will require the dreqency for which they were originally designed

Reply to
philo

Yeah, I realize that. My main use is going to be 'dimmed' resistive heater elements, so that shouldn't be a huge issue. The reason they were cheap was that they were surplus, really. Hopefully, 100V AC should be OK

Duly noted.

Gotcha. I'd more or less worked that out, but it's good to have it confirmed. Thanks for all the info!

Mattia

Reply to
Mattia Valente

It would be a proble for some devices yes.

A resistive heater would be OK.

Reply to
CWatters

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.