Transformer questions

[Boo2]

Hi,

I have decided to attempt the lost foam method of creating Sunrunner's new hatch garage and with the intent of making a hot wire cutter I unearthed (ahem) a brand new toroidal transformer which I put away ages ago believing the supplier had mislabeled it. I have now investigated using the resistance range on my dvm and I am pretty sure it is a 240V to 12V step down transformer with two independent secondaries. Most of the wiring is pretty obvious : black are mains input, red-yellow are the secondaries (with, presumably, red being one phase pair and yellow the other) but what are the 4 green wires ? I could understand them being the isolation shields, but surely there would either be 1 or 3 of these but not 4 ? (See pix below.)

Each of the green wires is isolated from each of the other green wires and all of the winding wires as well.

Can anyone tell me what is going on here and how these are meant to be wired up ?

Also, I bought a fused Euro chassis plug from Maplin today (part FT37S) which is rated at 10A 240V and inside the fuse chamber it says "6.3A 2.5W", can anyone tell me what this relates to ? 6.3A @240V is obviously not 2.5W...

 

[William_H]

Obviously a German transformer sw being black being mains input. A bit confusing rt-ge being red yellow. According to the lable the other 12v winding should be bl-gn I think blue green. (might be wrong.
Anyway for a hot wire supply I suggest you add a few turns (10) of heavy guage insulated wire around the toroid .ie through the hole and around again. This will give you a very low voltage but high current supply. I think 12v might be too high for typical 30cm of 18g SS wire. Even more so for iron wire. Vary the number of turns of heavy wire to get the temperature you want without (hopefully) overheating the primary. Just ignore (insulate) the green and red/yellow wires. If you decide you need the 12v windings. Put them in parallel and measure AC voltage. Connect your hot wire and ensure that the 12v AC dieoes not drop too much. Monitor the transformer temperature. good luck olewill

 

[Boo2]

Obviously a German transformer sw being black being mains input. A bit confusing rt-ge being red yellow. According to the lable the other 12v winding should be bl-gn I think blue green. (might be wrong.
Anyway for a hot wire supply I suggest you add a few turns (10) of heavy guage insulated wire around the toroid .ie through the hole and around again. This will give you a very low voltage but high current supply. I think 12v might be too high for typical 30cm of 18g SS wire. Even more so for iron wire. Vary the number of turns of heavy wire to get the temperature you want without (hopefully) overheating the primary. Just ignore (insulate) the green and red/yellow wires. If you decide you need the 12v windings. Put them in parallel and measure AC voltage. Connect your hot wire and ensure that the 12v AC dieoes not drop too much. Monitor the transformer temperature. good luck olewill

Thanks, Olewill, but I am really just after what the green wires do. Are they just connections to the shields dyk ?

I intend to run it off a dimmer module I already have which is supposed to work OK with an inductive load, though I agree a variable current source would be better - I just want to use what I already have to keep costs down.

Thanks,

Boo2

 

[nigelmercier]

Why not contact the manufacturer?