I posted a question a while ago about calculating the core size of a transformer when the frequency is relatively low (<50Hz). Thank you to everyone for the comments and feedback. I have done some more research and would like to post a follow up question outlining my thinking. I would really appreciate any comments.
I am interested in calculating the core size for a 20 Hz transformer. Single phase, step down. This is a theoretical question - I understand that low frequency transformers require core sizes that make them impractical, but I am just trying to understand how the core size would be calculated. For the purpose of understanding this, I have treated the transformer as a “perfect” transformer with no core losses - the thinking being that core losses could be factored in after I understand how the core size is worked out. (if this is a mistake, please let me know)
My primary coil has 400 turns & 8.05429 Voltage.
My secondary coil has 50 turns
The formula
(Voltage in Primary/turns on secondary coil)=(Induced Voltage in Secondary/turns on primary coil)
gives the induced Voltage in the secondary as 1.00678625, with a turns ratio of 400:50=8:1
I wanted to then use the following formula-
induced voltage = 4.44*fNA*B
Where f= frequency in Hz
N= number of turns in the coil
A= cross section of the core area in Meters
B= flux density in the core in Tesla
(I have done some FEMM simulations that give me a value for flux density in the core)
My questions:
1. I know the saturation point of the core material, so can I switch the formula
induced voltage = 4.44*fNA*B
to
B=induced voltage/(4.44fNB)
and then play around with plugging in values that deliver a value for B that is safely below the saturation point of the core material(e.g. 1.8T)?
2. How does the turns ratio of 8:1 influence the values for the Induced Voltage and the Number of Turns that I need to put in to the above formula? At first I thought I should just use the primary coil values, then I thought I should add the primary and secondary together. I have chased my own logic around like a dog chasing it’s tail and now lie in a dizzy heap! If anyone has any advice here, I surely would appreciate it. Thanks