how to build??

Dear All.., First of all let me thank you in advance for the kindest support u would be giving me answering my query. I am working in a electrical industry. I want to build a turns tester used to test the number of turns in a coil or a choke or transformer(primary/secondary). i ve some idea about this .. can anyone help me in this regard. I would like to tel what i know. There will be a transformer internally. The number of turns and voltage will be known. We now place a magnetic pillar which will carry the flux to the bobbin on which we rest our coil. the voltage developed across the coil/choke is checked and measured. The turns ration will then be V2/V1=N2/N1.. where we know V1,N1,V2.. so N2 can be calculated. This is how it is done.. but can anyone kindly elaborate how it shoud be done..

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hmmm... most mfr's know how many turns are in their product.... Maybe what you've been tasked with is testing the insulation between turns.... (when insulation is compromised the xfrmr appears to have fewer "turns").


while none of these ideas will tell you " X turns " (how large is that coil?, what size wire?, etc. etc.) here are a couple other testing methodologies:

  1. resonance : Xfmrs have a natural self resonance caused by their inductance and the capactance between turns. As a transformer becomes compromised the "Q" (peakedness) of that resonance will be affected.

  1. sounding : Using a TDR, shoot a pulse into it and see how long it takes before the echo returns to you.

pavan wrote:

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Try asking a Consumer Products Safety Commission:

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They'll probably know what standard tests you should be performing to verify the quality and safety of your cores to avoid any liabilities from fires and electrocutions and other problems.

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I think that these things are made in the UK by a company called H. Tinsley in Croydon.


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Chris Jones

One way to do this requires access to the core or bobbin of the transformer. What you do is put an extra one-turn winding on the transforemer and measure the voltage on the extra turn. If the voltage is too low to be measured accurately, increase the number of turns. Then measure the voltage on the extra winding. Divide this voltage by the number of turns to get volts/turn. Call this constant "K". Now the number of turns on the original windings can be calculated as N = V/K . K is independent of the number of windings, wire size, etc. Regards, Kral

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