Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Tubing for offline Flyback SMPS transformer

Status
Not open for further replies.
T

treez

Guest
Hello,

Page 18 to 20 of the below app note concerns the design of a transformer for a 65W Flyback SMPS.
The primary and the bias winding are simply specified to be wound with “magnet wire”. As you know, “Magnet wire” is not a brand, so it could be any type of Enamelled copper wire in theory.

The problem is that the bias winding output, and the drain end of the primary winding output, suffer pulsed voltages of some 500V between each other. Some types of “magnet wire” may not be able to handle this. I appreciate that the primary and the bias winding are not next to each other on the bobbin……however, as the wires are brought out of the bobbin to be terminated, they are highly likely to rest alongside each other…

..As such, why does the app note not make any stipulation for the isolation rating of the “magnet wire”? (As you know, they could have avoided this by specifying that the “magnet wire” termination ends gets wrapped with insulaion tubing, but they have neglected to do this.)

For example, does anyone know what is the insulation rating of this “magnet wire”?
https://www.farnell.com/datasheets/1683415.pdf

(The quoted British standard in the datasheet costs £102)

Der 243
https://ac-dc.power.com/sites/default/files/PDFFiles/der243.pdf?download=1
 

The application note refers to standard and triple insulated magnet wire. You find specifications of insulation strength in more detailed data sheets, which should be searched at magnet wire manufacturers not at catalog distributors. Together with the polyester tape layers, there's a rather complete description how to make the transformer. There are open points like the magnet wire temperature class. Without further specifications, I would expect lowest grade of standard polyurethane insulated magnet wire.

But it's a professional application note addressed to skilled engineers, not a DIY instruction. Some knowledge is taken as granted.

- - - Updated - - -

Here's a datasheet explaining the grade 2 specification **broken link removed**

You find more information on the product pages **broken link removed**
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
There is a 2 page version of that datasheet that gives more information. My search was " enameled copper wire - Farnell".
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
Here's a datasheet explaining the grade 2 specification **broken link removed**
Thanks FvM, it states that even the 0.2mm ECW is rated to 1800V.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top