[ZAC 1.4]

Impedance-based AC circuit simulator

 

INTRODUCTION

This program is a circuit simulator that finds numeric voltage in all nodes and numeric current in all branches of a circuit that contains (complex valued) impedances. It is the only circuit simulator for HP, as far as I know, that allows you to have defined branched impedances, so that you can know the current throw each impedance with no additional effort. All resistors, conductances and admitances are managed as impedances, too. When you've solved the circuit, you can find the Z, I, V, S, P, Q and fp of any impedance or voltage source.

A BIT OF HISTORY

I am an EE senior. I used to solve my circuits with Per Stenius' CSim2.61. It is such a great program! Last year I started studying circuits with impedances and found that the lack of a defined branch in impedances made it a hard job to analyze a circuit made mainly of impedances and admitances (such as those used in power systems failure analysis). So I started dreaming for a CSim that could define the branches of impedances and conductances, and that translated the whole circuit to impedances and that gived me an easy way to describe circuit and to retrieve answers. I asked Per to do that for me and he replied: "Do it yourself!" And I did it. Here it is: a circuit simulator made just to do that. No more need to invent a short circuit beside every impedance to know the current through that impedance! Here is how to use it.

STEPS TO SOLVE A CIRCUIT

  1. The first step in solving a circuit with ZAC is to number all nodes, starting from 0 which will be the ground. Then, when you've numbered all nodes, start from the number of the last node to number all the branches of the following elements: resistors, conductances, impedances, admitances, inductors, voltage dep. or indep. sources. For example, if you have three nodes, number them 0, 1 and 2. If you have two resistors and a voltage source, then their branches are 3, 4 and 5. See? It's easy. Write those numbers beside the nodes and elements in the drawing of the circuit, for you'll need them to remember how you asigned them. Until now, no key in the HP have been pressed.
  2. [ DESC ] - This is the second step in solving a circuit and is when HP appears: "Tataaaan!" Press DESC and a circuit descriptor will appear saying "Describe all elements." and that is what you will do, by selecting the elements one by one and giving the program the data of each one. The program will do two things: first, it will automatically describe all the elements in CSim notation so that you don't have to mess around with that; and second, it will translate every resistor, conductance and admitance to impedances. Why? Because this is a z-based software.
    1. You type 10 Ohm resistor, and the program writes (10,0) impedance.
    2. You type 20 Mho conductance, and the program writes (0.05,0) impedance.
    3. You type (2,-2) Mho admitance, and the program writes (0.25,0.25) impedance.
    4. You type (1,1) Ohm impedance, and the program writes just that.

    Be aware that in those elements that have a defined branch, the branch is defined from the node you imput as first to the node you imput as last, and that's the way the current answer will be given to you. When you finish describing the circuit, press CANCEL and you'll see in the stack a series of lists. That's the circuit description.

  3. [ STOC ] - Now that the circuit description is in stack, you have to store it in a variable called 'Circuit'. You do that by pressing STOC.
  4. [ STOw ] - Now store the frequency by putting its value (real number with no unit) in stack and pressing STOw. Frequency is important only if there are capacitors and inductors in the circuit. Otherwise, you can store any value and it will have no effect on the circuit.
  5. [ AC ] - This is the following step and the most important. You press AC and three things happen. First, the circuit description is analyzed. Second, ac analysis is performed. Third, answers are extracted and stored in variables named in the form a# where # is the number of node or branch in a directory called ANSWERS. After the last message you must press [VARS] key. The values of the variables mean this: a) If the number of the variable name corresponds to a node, then the value of the variable is the voltage of that node with regard to 0 node. (That's why 0 node does not appear, since his voltage with regard with himself is always 0 Volts.) b) If the number of the variable name corresponds to a branch, then the value of the variable is the current through that branch defined from the node you typed as first to the node you typed as last in the second step (DESC). If you want more info on any impedance or voltage source, just press [More] and then input the number of the branch of the impedance or voltage source you are interested in: the program will calculate and display in the stack the Z, I, V, S, P, Q and fp of this given element. Repeat this for as many impedances or voltage sources as you wish. When you finish viewing the answers, you press [Done] in the vars menu of that directory and it is gone forever.
  6. [ Info ] - The same that [ More ]. It requires you to be inside the 'Answers' directory.
  7. [ CLEAR ] - If user flag 1 is clear, the program will create a directory and perform all his operations in it, deleting it when the analysis is done. So you'll never see any variable except 'Circuit' and 'w'. So, if user flag 1 is clear, CLEAR is useless. But sometimes you want to see the impedance matrix and stuff. In those cases, set user flag 1. The vars used will remain in user memory. When you want to delete this variables, then press CLEAR and they are gone. To set flag type 1 SF and to clear it type 1 CF.

[ ABOU ] is just some info on me and how to find other software in my page. All for free...

SAVING CIRCUIT TO FURTHER USE

Just copy the 'Circuit' variable content to a variable with another name and that's it. When you want to use that circuit description again, save the content of that variable again in a variable called 'Circuit' and run ZAC. Isn't that easy?

QUESTIONS?

This program works fine, but use it at your own risk. If you have any question, asked me at hplus@i.am
Pay a visit to my site in http://i.am/hplus  or if you speak some spanish then go to http://pagina.de/Perez-Franco   or http://w3.to/utp  if you are a student of UTP (my university).

:o) Enjoy!

Roberto Perez-Franco (HPlus!)
http://i.am/HPlus HPlus@i.am icq#14607303
Universidad Tecnológica de Panamá - Marzo 17, 1999.

P.S. If you believe in peace, then visit http://w3.to/pax and join us!