The question is find R Thevenien using Voltage test source across terminals a and b of the following circuit:(adsbygoogle = window.adsbygoogle || []).push({});

http://img255.imageshack.us/img255/8660/rthevenen.png [Broken]

I did it by adding a 20 test voltage source and used mesh to get the following 4 equations of the 4 meshes ( I deactivated the 480 V independent source to be able to use test voltage method)

M1:6(x-t) + 40(x-y)+4x=0

M2: 40(y-x)+20=0

M3: 80(z-t) - 20q +2z-20=0

M4:4t + 8(t-z) +6(t-x)=0

q=x-t

I R thevenen to be 11.55 but actually the correct answer is 12 ohms.

Where is my mistake.

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# Help in finding R Thevenien?

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