Author Topic: Soft Transformer Wire  (Read 1845 times)

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Offline queennikki1972Topic starter

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Soft Transformer Wire
« on: October 02, 2019, 01:30:25 am »
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.
« Last Edit: October 02, 2019, 02:49:22 am by queennikki1972 »
Siglent SDS 1202X-E - Heathkit IO-4105 - Dr. Meter 0-30v 5a power supply - 862d+ combo unit - Weller WLC100 - Kunkin KL283 DC load. Not much gear yet.
 

Offline queennikki1972Topic starter

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Re: Soft Transformer Wire
« Reply #1 on: October 02, 2019, 01:33:49 am »
Siglent SDS 1202X-E - Heathkit IO-4105 - Dr. Meter 0-30v 5a power supply - 862d+ combo unit - Weller WLC100 - Kunkin KL283 DC load. Not much gear yet.
 

Offline soldar

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Re: Soft Transformer Wire
« Reply #2 on: October 02, 2019, 06:53:25 am »
Sometimes transformers come with soft flexible wire rather than rigid.

Only very big transformers would use multistrand wires for windings.


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.

Depends on the size and power but definitely not "soft and flexible".


Modified ; I should say its used on foot transformers and is shielded cable.

Shielded? You are all over the place. I have no idea what you are trying to ask. Maybe you can try to clarify?
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Offline soldar

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Re: Soft Transformer Wire
« Reply #3 on: October 02, 2019, 06:54:39 am »
It's called Litz wire.

Definitely not for power transformers.
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Offline soldar

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Re: Soft Transformer Wire
« Reply #4 on: October 02, 2019, 08:32:44 am »
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 normal rigid or multistrand cables. 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.

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Offline Kleinstein

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Re: Soft Transformer Wire
« Reply #5 on: October 02, 2019, 09:42:15 am »
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.
 

Offline queennikki1972Topic starter

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Re: Soft Transformer Wire
« Reply #6 on: October 02, 2019, 12:47:32 pm »
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
« Last Edit: October 02, 2019, 12:55:39 pm by queennikki1972 »
Siglent SDS 1202X-E - Heathkit IO-4105 - Dr. Meter 0-30v 5a power supply - 862d+ combo unit - Weller WLC100 - Kunkin KL283 DC load. Not much gear yet.
 

Offline Zero999

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Re: Soft Transformer Wire
« Reply #7 on: October 02, 2019, 01:04:57 pm »
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.
 

Offline queennikki1972Topic starter

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Re: Soft Transformer Wire
« Reply #8 on: October 02, 2019, 01:16:44 pm »
120vac/24vac 75VA foot transformer 7" run of primary and secondary wires . flexible multi strand cable.
« Last Edit: October 02, 2019, 01:18:49 pm by queennikki1972 »
Siglent SDS 1202X-E - Heathkit IO-4105 - Dr. Meter 0-30v 5a power supply - 862d+ combo unit - Weller WLC100 - Kunkin KL283 DC load. Not much gear yet.
 

Offline schmitt trigger

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Re: Soft Transformer Wire
« Reply #9 on: October 02, 2019, 01:48:17 pm »
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.
 

Offline MagicSmoker

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Re: Soft Transformer Wire
« Reply #10 on: October 02, 2019, 02:16:59 pm »
120vac/24vac 75VA foot transformer 7" run of primary and secondary wires . flexible multi strand cable.

Lots 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.html

The 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.
 

Offline tooki

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Re: Soft Transformer Wire
« Reply #11 on: October 02, 2019, 05:23:41 pm »
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.
Just 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 specifically and exclusively the special stranded wire where each strand is insulated with enamel ("Hochfrequenzlitze" in German). We never, ever say "litz" to mean regular stranded wire.

See https://en.wikipedia.org/wiki/Litz_wire, https://de.wikipedia.org/wiki/Litze_(Elektrotechnik), and https://de.wikipedia.org/wiki/Hochfrequenzlitze


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.
FYI, in English, "shielding" in electronics means shielding against EM interference. I'm pretty sure you mean insulation.
 
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Offline Zero999

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Re: Soft Transformer Wire
« Reply #12 on: October 02, 2019, 05:52:25 pm »
120vac/24vac 75VA foot transformer 7" run of primary and secondary wires . flexible multi strand cable.
The 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.
 


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