Wire size !

Thread Starter

spike1947

Joined Feb 4, 2016
383
Hi
I am going to rewind a small transformer, the size of the wire it had on was 0.06mm x 9 strands in a bunch, I can't find that size anywere and if I did I would need 9 bobins of that size, I would like to know what single strand size wire I could use that would carry the same current !.

Cheers
Spike
 

Thread Starter

spike1947

Joined Feb 4, 2016
383
Yes, but this one had multi strands joined, I just need the mathamatics here, as to what size in mm2 or Ǿ for a single core wire.
my brain is not working of late .

cheers
Spike
 

Ian0

Joined Aug 7, 2020
4,119
I don't think that is the way, if I did that with. 2.5mm2 and times that by 4 I would get 10mm2, but I don't think the loading of 4x2.5mm2 = 1x 10mm2 !.
Spike
Actually it is. (It's different for high frequency transformers >100kHz)
Think about stranded mains flex vs. solid conductor wires that you wire your house with
1.5mm^2 mains flex will carry the same current as 1.5mm^2 twin-and-earth.
1.5mm^2 mains flex is generally stranded at 30x0.25mm
\(
30 \times \pi (\frac { 0.25\cdot 10^{-3}}{2})^2 = 1.473mm^2
\)
 

Tonyr1084

Joined Sep 24, 2015
6,611
Not the greatest at math but I think I came up with something much smaller than what you all are saying.

Here's my path:
0.06 dia ÷ 2 = 0.03 radius
Pi R^2
0.03 x 0.03 =0 .0009
0.0009 x 3.14 (pi) = 0.002826 area
0.002826 x 9 (strands) = 0.025434

Now, I know even less about high frequency transformers.
 

Ian0

Joined Aug 7, 2020
4,119
Just a thought - are you sure that it is 9 strands throughout the winding, or just from the bobbin to the terminals?
Transformers with very fine wire have the wire "skeined" between the end of the winding and the terminal.
 

Thread Starter

spike1947

Joined Feb 4, 2016
383
Just a thought - are you sure that it is 9 strands throughout the winding, or just from the bobbin to the terminals?
Transformers with very fine wire have the wire "skeined" between the end of the winding and the terminal.
Yes def 9 strands, and yes they are all soldered together at each end at the last 10mm where they terminate at the spade terminal .
ps: Not possible to scrape off the enamel/laquer too fine just breaks when trying.

cheers
Spike
 

MisterBill2

Joined Jan 23, 2018
10,533
This postseems a lot like meowsoft's transformer and if the wires are soldered together for the whole length and not insulated then it will result in short circuited tuens and the transformer will fail rather quickly when power is applied. The reason for using multiple strands in a mains power transformer is to make the wire easier to wind..
 

Thread Starter

spike1947

Joined Feb 4, 2016
383
This postseems a lot like meowsoft's transformer and if the wires are soldered together for the whole length and not insulated then it will result in short circuited tuens and the transformer will fail rather quickly when power is applied. The reason for using multiple strands in a mains power transformer is to make the wire easier to wind..
Hi
Thanks for your reply, each strand is insulated like laquered
 

MisterBill2

Joined Jan 23, 2018
10,533
Hi
Thanks for your reply, each strand is insulated like laquered
Wire with insulated strands is called "Litz wire" and is useful for higher frequency applications. It offers NO ELECTRICAL BENEFIT AT ALL at mains frequencies. it would be easier to wind than an equivalent solid wire but that makes no sense for this application.
When the transformer unwinding process is completed perhaps the reason for using that type of wire will become clear. If that wire is indeed used t connect to the 400volt low current winding then it is probably used as a short extension of the much finer wire used for the many low-current turns required. Rather unusual to see it done that way.
 

Thread Starter

spike1947

Joined Feb 4, 2016
383
Wire with insulated strands is called "Litz wire" and is useful for higher frequency applications. It offers NO ELECTRICAL BENEFIT AT ALL at mains frequencies. it would be easier to wind than an equivalent solid wire but that makes no sense for this application.
When the transformer unwinding process is completed perhaps the reason for using that type of wire will become clear. If that wire is indeed used t connect to the 400volt low current winding then it is probably used as a short extension of the much finer wire used for the many low-current turns required. Rather unusual to see it done that way.
Hi
Thanks for your reply, I have all ready unwound the 400v winding, I had to do that first to get at the primary winding were the fault lies, have new primary wire but not the 400v secondary wire .

Note: The 400v secondary winding is laid on top of the primary winding !.
cheers
Spike
 
Top