• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Individually Enameled Stranded Wire?

Status
Not open for further replies.

dknguyen

Well-Known Member
Most Helpful Member
Is there such a thing as multi-stranded wire where every strand is individually enameled? (I would assume for increased current capacity at high currents).

I know there is enameled solid wire, but I have been getting the impression that wire exists that as I described.
 

Tesla23

Member
Is there such a thing as multi-stranded wire where every strand is individually enameled? (I would assume for increased current capacity at high currents).

I know there is enameled solid wire, but I have been getting the impression that wire exists that as I described.
Litz wire

But not for increased current carrying capacity (why would you expect this?), the increased surface area reduces hihg frequency losses.
 

mneary

New Member
Yes, this is Litz wire. It's for lower losses at higher frequencies. See Wikipedia for more.
 

dknguyen

Well-Known Member
Most Helpful Member
Same thing. Lower loss = higher capacity.

Is this wire very rare or very expensive? Would it be used in the large AWG ranges (like 18-12) on something like a RC hobby grade brushless motor? I want to replace the soldered connectors on some motors with some crimped connectors. It would be better if I just chopped off the soldered connectors altogther so I am not crimping to solder-tinned wires.

I have read that it is not recommended to shorten the motor leads though (despite less inductance). The reasons seem to be inconsistent. They seem to vary from the external power wires of the motor being enamel covered (one post implied that every single strand was enamel covered), to the wire length acting as a heatsink thus isolating the drive electronics from the motor's heat.
 
Last edited:

Tesla23

Member
Same thing. Lower loss = higher capacity.

Is this wire very rare or very expensive? Would it be used in the large AWG ranges (like 18-12) on something like a RC hobby grade brushless motor? I want to replace the soldered connectors on some motors with some crimped connectors. It would be better if I just chopped off the soldered connectors altogther so I am not crimping to solder-tinned wires.

I have read that it is not recommended to shorten the motor leads though (despite less inductance). The reasons seem to be inconsistent. They seem to vary from the external power wires of the motor being enamel covered (one post implied that every single strand was enamel covered), to the wire length acting as a heatsink thus isolating the drive electronics from the motor's heat.

Litz wire is a fairly specialist item now, it is almost certainly available but I don't know where.

It is only 'lower loss' when the frequency gets into the MHz range, for frequencies in the kHz and below for lowest loss you are almost certainly better off replacing the laquer and voids between the conductors with more copper and just using solid copper. It will also be much cheaper. Depending on the wire gauge I'd expect solid copper to outperform litz wire at frequencies below 10kHz.
 

Dean Huster

Well-Known Member
Litz wire was commonly used for headphone cables as it was very flexible. It's a royal pain to work with as soldering is very, very difficult. It's not made with round cross-section wire, but with wire ribbon, usually wound around a paper core. I think that when you look at its normal uses, you'll find far more instances of it in headphone cords and electric shaver power cords than you will in HF electronics.

Dean
 

crutschow

Well-Known Member
Most Helpful Member
Litz wire is sometimes used in high frequency DC-DC converter power transformers or inductors to reduce skin effect loses in the wire.
 

crutschow

Well-Known Member
Most Helpful Member
Litz wire was commonly used for headphone cables as it was very flexible. It's a royal pain to work with as soldering is very, very difficult. It's not made with round cross-section wire, but with wire ribbon, usually wound around a paper core. I think that when you look at its normal uses, you'll find far more instances of it in headphone cords and electric shaver power cords than you will in HF electronics.
That's obviously a different type of wire than the Litz wire used for high frequency applications. The headphone wire would not need to have the individual wires insulated from each other since there's no skin effect to be concerned about.
 

Diver300

Well-Known Member
Most Helpful Member
That's obviously a different type of wire than the Litz wire used for high frequency applications. The headphone wire would not need to have the individual wires insulated from each other since there's no skin effect to be concerned about.
I have seen something like Litz wire used for headphone wire where the enamelling is all that insulates the Left and Right from each other and ground.
 

Speakerguy

Active Member
I tried to make my own multi-conductor stranded wire from enameled wire. It doesn't work too well if you need a long length and want it to look pretty. My application was a Tesla coil primary for a 4MHz secondary.
 

ericgibbs

Well-Known Member
Most Helpful Member
That's obviously a different type of wire than the Litz wire used for high frequency applications. The headphone wire would not need to have the individual wires insulated from each other since there's no skin effect to be concerned about.
This is also my understanding of Litz wire, I wound long wave radio coils when I was a boy, using this type of wire. [skin effect]

The headphone flexi-cable is somewhat different in construction in order to make it more flexible and durable than Litz.


http://www.litzwire.com/litz_types.htm
 
Last edited:

Sceadwian

Banned
Skin effect is not an issue at the frequencies and wire thickness's you're using DK.

Take a look at this calculator.
Skin Effect Calculator

Type in 10khz which I'm assuming is no higher than the PWM of your brushless motor. The penetration is equivalent to the wire thickness with 15 gauge wire. So you're JUST starting to see skin effect on anything larger than 15 gauge. You could completely solve the problem at 10khz if you wanted 12 gauge wire by using two strands of 15 gauge wires in parallel.. Litz wire is wasted money and effectively useless in your application.

If the PWM of your motor controller is closer to 1khz skin effect won't even occur till 5 guage wire.
 
Last edited:

codan

New Member
Hi DK,

Litz wire is useful for some coil winding applications as well such as metal detector coils because it minimises the interwire capacitance which is important for this application.
 

dknguyen

Well-Known Member
Most Helpful Member
I wonder why people seem to have to strip "something" (not insulation!) from the leads of motor wires then before soldering since the solder won't adhere (I am also assuming that it will not conduct as well as it should).
 

tcmtech

Banned
Most Helpful Member
Often times the stripping of an already bare wire is to actually remove oxidation or some contamination from the surface of the wire in order to get the solder to take hold.
I do it a lot when working with old stuff or stuff thats been in wet or corrosive environments. The oxidation on wire can get thick enough that the solder flux cant do its job and the solder just wads up and wont flow or stick.
 

dknguyen

Well-Known Member
Most Helpful Member
It's hard to say. SOme people say that the motor power wires are just extensions of the winding wires which are enameled cover, but that sounds wrong...an entire motor being coiled from a wire whose strands have been separated on one end. FOr all I know, the motor power wires being enamel covered is absolutely false and you just aren't supposed to shorten the motor wires for other reasons, and RC hobbyists have just wrongly extended the enamel covering of the motor windings to the power leads to explain this.

It's kind of catch-22. If I chop off the wires and crimp the original connectors on and find that the resistance is too high due to some coating on the strands, then I have just lobbed off the pre-tinned end of the wires when I lobbed off the original connectors.
 
Last edited:

MrAl

Well-Known Member
Most Helpful Member
Hi,

One of the main advantages of Litz wire is that it allows one to increase the current
density in a given construction. For some coil operating at some high enough
frequency, winding it with say 12 gauge wire and energizing that wire as per the
application would be similar to winding it instead with some tiny wire like 32 gauge
along side of another wire of close to 12 gauge wire, but only energizing the
32 gauge wire! Thus, all that space that the 12 gauge wire takes up is lost,
leaving only the 32 gauge wire to do the conduction. This means that a lot
of core window space is lost. By using all 32 gauge insulated wire (for example)
all of those strands will be taking part in the conduction and so the entire core
window space will be utilized more effectively.

There are other uses though that have nothing to do with current density as others
have pointed out. I guess it is also possible that some designer mistakes a not so
good application for this wire for a good application, and uses this wire anyway.
That would mean we would have to deal with the enamel coating on each wire
anyway. If that happens to be the leads to a motor and we want to crimp a
lug or something to the end of that wire, we would first have to remove all of
the enamel from the end of the wire up to a distance that allows proper contact
with the wire (say 3/4 inch or so). We may even want to strip a little more off
and fold back the wire on itself at the end so when we crimp the wire lug on the
end it has more to grab on to.

The problem is, how to get rid of the enamel. Some enamel is removed using
a special rotating tool that scrapes off the insulation, but sometimes it can
even be burnt off with a good soldering iron. It all depends on the grade of
the enamel on the wire. Some burns off pretty fast, others take longer.
Some you can dip into a solder pot and that tins the ends in a few seconds.
If you dont want solder on the wire, then you have to find a way to get rid
of the enamel without soldering and at the same time without damaging the
wire.
The only way i know of to do that is to find that special tool that is made for
stripping enameled wire. I dont know myself where to find one or how much
it costs, but there is always the possibility of searching on the web.
[check out the "Eraser", as it is called]
The other way is to use a razor blade and gently scrape off the insulation,
but obviously some of the wire may get damaged.

Alternately, the lugs can be soldered on. That may not be as good as a crimp
however, so this is something that has to be thought about.

I would say definitely try one lead alone before hacking them all off.

Good luck with it...
 
Last edited:

dknguyen

Well-Known Member
Most Helpful Member
I was told you could burn it off, then use Baker's Solution to remove the oxide. One person in particular specifically said a methyl spirit flame and to dunk it in methyl spirits afterwards and not to breathe anything in. THe only methyl stuff I know of is methyl hydrate and that stuff is as toxic as $#@%&.

I may also be getting confused when people say "shorten motor wires" because the vast majority of the time it seems like they are talking about the speed controller output wires (that connects to the power wires on the motor), not the motor's power wires. However, one manufacturer specifically says to not shorten the motor's wires, but to shorten the speed controller output wires instead. However, I did just find a post where someone specifically says

"The wires that the motors are wound with are insulated from each other with resin. This insulation resin often extends in to the three wires leading from the motor. If you shorten the wires and reach this area of insulation then you will not make contact and the motor will not work."

Personally, I don't even know how they would pull this off "extending the resin insulation of the motor windings to the exernal power wires."

I'm realy curious now. I have 6 brushless motors here way more than I need since I dropped a project for the time being. But destroying the wire on a perfectly good motor just to find out if it's realy resined or not is a waste. I suppose I could open it up to see how the motor power wires are connected to the windings (continuous wire or soldered connection)
 
Last edited:

MrAl

Well-Known Member
Most Helpful Member
Hi again,

Do you know what kind of motor this is, such as stepper, standard permanent
magnet, brushless, etc. ?
Also, would it be possible to post a few pics of this thing, like one full view and
one close up of the wire connections?
 

dknguyen

Well-Known Member
Most Helpful Member
I've got no photos nor have I seen any of where the coil wire turns into the power wire. But I e-mailed a manufacturer and and they said:

"This wire is used to wind the stator, and about 4-5 inches of extra wire is left at the end of each phase winding. These wires become the motor leads. They are twisted together and covered with heat shrink tubing. At the very end of the wire bundles, the tips are dipped into a solder pot that burns off all the enamel insulation, and the solder tins the copper underneath to prepare it for soldering the bullet connectors to the wire."

So I guess I guess the same wire that makes the coils is the same wire that makes the power leads. I had always assumed they were two separates wires, then again I've also never thought about never seeing a solder blob connect the power leads to the coil windings. Not really litz wire, but similar result. I guess I'll just solder on the wire crimps and crimp everything else.
 
Last edited:
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top