Maximum permissible temperature of a Ferrite core transformer

Discussion in 'General Electronics Chat' started by SVS, Aug 12, 2015.

  1. SVS

    Thread Starter Member

    Aug 16, 2012
    89
    4
    Hello Everyone,

    I have a 1KW ferrite core transformer that transforms 250V AC to 3-5kV in between ( 30-90 kHz).
    I made a long duration test for 8 hours with maximum load.

    The temperature results are as follows:
    Windings : 95°C
    Ferrite Core : 100°C @ 30kHz
    115°C @90kHz

    Room temperature is around 40°C .( testing in a hot environment).

    NOTE:The transformer doesn't have any fans / ventilators for cooling. But the complete transformer is potted in a housing with a epoxy material to enhance the electrical isolation. The potting material has a decent thermal conductivity.
    The potting material,litz wire in the transformer and the ferrite core can withstand up to 175°C.

    Is this too hot for a 1kW transformer?
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,792
    945
    115 C is well under the max temp of 175 C you have given.
    You are safe.
     
    Hypatia's Protege likes this.
  3. SVS

    Thread Starter Member

    Aug 16, 2012
    89
    4

    Thank you for the reply first of all..

    I know that I am well under 175°C , but the question is, Is it normal for the transformer to get so hot ?
    Does this high temperature influence the long time durability of the transformer ? ( Due to constant thermal expansion and contraction )?

    I just wanna know from the members who have worked with these kinda transformers. Please share your experience .
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    if you get the core above the Currie temp, it will not work. try to find the specs for the core.
     
  5. SVS

    Thread Starter Member

    Aug 16, 2012
    89
    4
    Yes. The curie temperature is 210°C. So, it is well below that :)

    Any other factor?
     
  6. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    The inner temperature on the windings might be a bit more, so I would start questioning what the isolation on those can withstand.
     
  7. SVS

    Thread Starter Member

    Aug 16, 2012
    89
    4
    The windings are actually vacuum impregnated with a material which can withstand upto 180°C.
    Assuming that every winding has this material coating !!

    Thank you!
     
  8. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Imagine three tightly wound windings, one on top of the other two, the three points in the crossection where these are touching will most probably stay untouched by the impregnation and there will still be only a little bit of isolation material between them. This makes me feel that the maximum temperature for the original enamel coated wire should be taken into account too.
     
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