Transformer steel. M6 vs Z11

Discussion in 'DIY' started by Zampotech, Sep 8, 2021.

  1. Zampotech

    Zampotech Friend

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    At the beginning of this year, I ordered transformer steel of the Z11 type for the manufacture of new SW4 and SW9 amplifiers.

    I have never worked with this steel, I knew only from reviews and rumors.

    When I had a little time, I decided to conduct comparative tests of steel of the M6 and Z11 types.

    To begin with, I put together a magnetic circuit measurement unit from an electrical engineering textbook.

    [​IMG]

    Then I assembled two transformers on different magnetic cores, but with the same coils.
    The left transformer with a dark core is with a Z11 magnetic core, the right transformer with a light core on a M6 magnetic core

    [​IMG]


    The first tests. Measurement of the inductance of the core without a gap.

    - Z11 - 20,68 H

    [​IMG]

    - M6 - 12,35

    [​IMG]

    It can be seen that the initial magnetic permeability of Z11 is noticeably greater.

    The second test. We visualize the hysteresis loop in the core without a gap.

    - Z11 steel hysteresis loop

    [​IMG]

    - M6 steel hysteresis loop

    [​IMG]

    It can be seen that the coercive force of M6 steel is greater, which means there are more losses in it. But not much.

    The next test, visualization of the hysteresis loop with a gap in the magnetic circuit of 0.1 mm. For this purpose, the transformers were disassembled and paper with a thickness of 0.1 mm was placed between the plates E and I

    - Z11 (0.1mm)

    [​IMG]

    Zoom in horizontally

    [​IMG]

    - M6 (0,1mm)

    [​IMG]

    Zoom in horizontally

    [​IMG]

    The characteristics have become very similar.

    But the initial inductance of Z11 turned out to be greater, 12.7 H (Z11) versus 8.75 H (M6)

    From this I concluded that both brands of steel are suitable for a high-quality transformer, but the Z11 is still better.
     
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  2. gixxerwimp

    gixxerwimp Professional tricycle rider

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  3. Armaegis

    Armaegis Friend

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    Simplified:
    - top curve is the amount of energy you put in to do the thing
    - bottom curve it the amount of energy you get out when you undo the thing
    - the difference is your energy loss
     
  4. Priidik

    Priidik MOT: Estelon

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    Nice work. How thick are the laminations of the Z11 material?

    Few pointers:
    - the hysteresis losses are only one source of losses, the arguably more significant one for audio are eddy current (Foucault's losses) losses, which unlike hysteresis (proportional) is squared wrt frequency. It would be interesting to see some analysis in the 1 kHz to 10 kHz range. (Once you have introduced airgap to the core, as can be seen the hysteresis is almost negligible. )
    - do you have access to M3 oriented steel (same as M6, only thinner lamination)?
     
  5. Zampotech

    Zampotech Friend

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    The plates Z11 and M6 have a size of EI66 and a thickness of 0.35 mm


    No, I don't have access yet

    good idea. I'll think about how to do it.
     
  6. famish99

    famish99 Friend

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    The biggest reason for an air gap in an OPT is that without it, the DC flowing through the primary would melt the transformer.
     

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