Soft Transformer Wire - Page 1
Forum section: electronics / beginners

author: queennikki1972
author_rank: Regular Contributor
timestamp: October 02, 2019, 01:30:25 am
content: Sometimes transformers come with soft flexible wire rather than rigid. What gauge is recommended for 120vac transformer primary side with say 24vac secondary of stranded wire and what is the soft flexible type of wire called? Links to it online would be helpful.Modified ; I should say its used on foot transformers and is shielded cable.

author: queennikki1972
author_rank: Regular Contributor
timestamp: October 02, 2019, 01:33:49 am
content: Is this it? and what gauge?https://www.amazon.com/10-Gauge-Silicone-Wire-Feet/dp/B007DMW3IU

author: soldar
author_rank: Super Contributor
timestamp: October 02, 2019, 06:53:25 am
content: Quote from: queennikki1972 on October 02, 2019, 01:30:25 amOnly very big transformers would use multistrand wires for windings.Quote from: queennikki1972 on October 02, 2019, 01:30:25 amDepends on the size and power but definitely not "soft and flexible".Quote from: queennikki1972 on October 02, 2019, 01:30:25 amShielded? You are all over the place. I have no idea what you are trying to ask. Maybe you can try to clarify?

author: soldar
author_rank: Super Contributor
timestamp: October 02, 2019, 06:54:39 am
content: Quote from: blueskull on October 02, 2019, 01:55:46 amDefinitely not for power transformers.

author: soldar
author_rank: Super Contributor
timestamp: October 02, 2019, 08:32:44 am
content: Oh, OK, I think I am beginning to understand. We are not talking about the windings of the transformer but about cables used to connect the transformer to whatever. You can just use your normalrigid or multistrandcables. The gauge will obviously depend on the current but generally for short runs and low power you can use 1.5 mm2 and be overdoing it.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 02, 2019, 09:42:15 am
content: For the transformer itself stranded wire is sometimes used for RF. This is than special litz wire with insulation. There is no need to use this for normal main's frequency. Toroidal transformer for low voltage may sometimes use multiple thinner wires to avoid thick and very stiff wires that may not be compatible with the machines used. The choice there really depends on the details.

author: queennikki1972
author_rank: Regular Contributor
timestamp: October 02, 2019, 12:47:32 pm
content: Yes I tried to clarify, its a power transformer aka foot mounted transformer and its the external hook up wires.. Its for short runs about 7". I thought it would be about 12awg but I didn't know if i could get away with 14awg

author: Zero999
author_rank: Super Contributor
timestamp: October 02, 2019, 01:04:57 pm
content: There isn't enough information to answer your question. What's the power rating of the transformer? The gauge of the wires, depends on the current, which is proportional to the transformer's power rating.There's also a minimum wire gauge irrespective of current, for mechanical stability's sake, which is often set by regulations. For example in the UK, the minimum cross-sectional area for external mains cables is 0.5mm2, even if the current is tiny.For long cable runs, the voltage drop is an issue, but not in this case as it's short.

author: queennikki1972
author_rank: Regular Contributor
timestamp: October 02, 2019, 01:16:44 pm
content: 120vac/24vac 75VA foot transformer 7" run of primary and secondary wires . flexible multi strand cable.

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 02, 2019, 01:48:17 pm
content: If I understand the post correctly (and this is a big *if*), the OP is asking not about the wire used to wind the transformer itself, but the actual wires which comprise the input and output of the transformer.

author: MagicSmoker
author_rank: Super Contributor
timestamp: October 02, 2019, 02:16:59 pm
content: Quote from: queennikki1972 on October 02, 2019, 01:16:44 pmLots of different wires can be used as long as they are UL Approved for Class 2 transformers (which this kind is) and an "AWM" type (ie - appliance wire). See more about AWM here:https://www.anixter.com/en_us/resources/literature/wire-wisdom/understanding-and-identifying-ul-awm-styles.htmlThe amperage on the primary is going to 75VA / 120VAC = 0.625A so go with #18 or #20 AWG wire - mainly for mechanical, rather than amperage, reasons - and the secondary will be 3.125A so #16 AWG will suffice here.

author: tooki
author_rank: Super Contributor
timestamp: October 02, 2019, 05:23:41 pm
content: Quote from: Kleinstein on October 02, 2019, 09:42:15 amJust to be clear, there is a (significant) mismatch between the German "Litze" and the English "litz wire".German "Litze" is called "stranded wire" in English. In English, when we say "litz wire", it means specificallyand exclusivelythe special stranded wire where each strand is insulated with enamel ("Hochfrequenzlitze" in German). We never, ever say "litz" to mean regular stranded wire.Seehttps://en.wikipedia.org/wiki/Litz_wire,https://de.wikipedia.org/wiki/Litze_(Elektrotechnik), andhttps://de.wikipedia.org/wiki/HochfrequenzlitzeQuote from: queennikki1972 on October 02, 2019, 01:30:25 amFYI, in English, "shielding" in electronics means shielding against EM interference. I'm pretty sure you meaninsulation.

author: Zero999
author_rank: Super Contributor
timestamp: October 02, 2019, 05:52:25 pm
content: Quote from: queennikki1972 on October 02, 2019, 01:16:44 pmThe maximum secondary current will be 3.125A and the primary just over a fifth of that. In the UK mains flexible cables need to have conductors with a crossectional area of at least 0.5mm2, which is equivalent to 20 AWG, so use that for both the primary and secondary connections and you should be fine.