Calculating Thevenin Voltage/Norton Current

ydgmms

Joined Oct 6, 2007
10
I'm having massive trouble calculating Thevenin Voltage and Norton Current (eventually Thevenin Resistance - using Ohm's Law) at the nodes A and B (60V and 56V respectively) in the circuit attached.

I honestly don't totally know where to begin or which method to follow through.

After looking at it for some time, I said 'superposition'. Calculating the Voltage at A and B with each 2/3 sources removed then adding the resultants together.

I started to do that, I of course checked my progress with pSpice, and seemed to be in the right frame of mind I thought.

For example, when shorting the 20V source and opening the 20A source, I was able to get 11.25V at point A. Then when trying to calculate the voltage at point B (should be 2.25V) I ran into some Wye-Delta Transformation problem, and was stuck trying that out.

Then I thought, source transformation just to get rid of the current source, but dunno where to go from there.

I'm *ass*uming I'm going about it wrong. Needing to use some Mesh analysis? My professor assigned some other homework (with only one source) and after the majority of the class got it wrong, he gave a walkthru guide, but hell if I truly understood it. The professor doesn't really go into a lot of detail about anything, just glosses over every subject. The class is really helping everyone out. But being the weekend, and me only have 2 of their email addresses - am stuck.

Just some kind of 'hey try doing -such n such-' maybe a quick example?
Much appreciated. Will keep at it.

Attachments

• 44.9 KB Views: 55

techroomt

Joined May 19, 2004
198
thevenizing is performed to two terminals (nodes), is that where the 80v and 56 v are listed? any method can be used to simplify the circuit. superposition will work - make sure to leave one power source in at a time, replace voltage sources with a short and current sources with an open.

ydgmms

Joined Oct 6, 2007
10
Yeah. Node A is the 60V point and Node B is the 56V point.

I'm currently trying Mesh Analysis...