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## Re: [Qucs-help] Using in 277V System for Grounding Seminar

 Re: [Qucs-help] Using in 277V System for Grounding Seminar From: Frans Schreuder - 2014-04-24 07:50:54 ```Hi Ruben, I guess what you want is a transient simulation, not an AC simulation. (although you have an AC voltage source which you should set to 60 Hz, you still want to have your results in the time domain right?) >> >> On 04/23/2014 02:10 AM, Ruben S Corvalan P.E. wrote: >>> Hi: >>> >>> I am writing an engineering manual for an electrical grounding >>> seminar. I was looking for a circuit simulator to calculate the >>> steady state, 60 Hz, ground fault voltage drop at different >>> locations of the electrical distribution system during a ground fault. >>> >>> I modeled the system as follows. >>> >>> Mail attachments can't be sent to this mailing list, I have added your attachment to dropbox: https://www.dropbox.com/s/gynq3x99pnvz2i3/PastedGraphic-1.png >>> >>> I am interested in knowing the voltage at locations MCC and SE. Can >>> this be done: >>> >>> I have several questions: >>> >>> 1. I assume that the voltage source in your model assumes it >>> delivers infinite current. That is., an ideal voltage source. This >>> is not true in practical systems. We have a Utility service feeding >>> a transformer. The utility provides a maximum short circuit current >>> at a certain voltage. The utility delivers voltage with a maximum >>> current. The transformer changes the voltage but has an internal >>> impedance. In your model the transformer does not have primary or >>> secondary voltage levels, only the voltage ratio.It ou can I model >>> this utility - transformer combination? Well, the maximum voltage (usually VA) in a transformer has something to do with the iron saturation in a transformer, the ideal inductor doesn't deal with this. You could also give the coupled inductors a try. >>> >>> I assume that I entered the values of resistance in a correct way my >>> specifying m Ohm representing milli Ohms. Is this correct.? Correct, you don't need the space in between m and Ohm, but it is alright. >>> >>> It would be great I could use this program in my grounding seminars. >>> But if this program is not the adequate, do you know of circuit >>> simulator program more geared to power? I have SKM software but I >>> can’t draw single phase diagrams like the above and I can not use >>> SKM for this grounding analysis. I think qucs is quite powerful, but like in any simulator you have to chose the right models. Like for your motor you are using a resistor, you probably also want to have at least an inductive component in there. There may be simulators available that have motor models available but I am not aware of them. Just play around and chose which simulator fits you better. >>> >>> Thanks. >>> >>> >>> >>> >> > ```

 Re: [Qucs-help] Using in 277V System for Grounding Seminar From: Frans Schreuder - 2014-04-24 07:50:54 ```Hi Ruben, I guess what you want is a transient simulation, not an AC simulation. (although you have an AC voltage source which you should set to 60 Hz, you still want to have your results in the time domain right?) >> >> On 04/23/2014 02:10 AM, Ruben S Corvalan P.E. wrote: >>> Hi: >>> >>> I am writing an engineering manual for an electrical grounding >>> seminar. I was looking for a circuit simulator to calculate the >>> steady state, 60 Hz, ground fault voltage drop at different >>> locations of the electrical distribution system during a ground fault. >>> >>> I modeled the system as follows. >>> >>> Mail attachments can't be sent to this mailing list, I have added your attachment to dropbox: https://www.dropbox.com/s/gynq3x99pnvz2i3/PastedGraphic-1.png >>> >>> I am interested in knowing the voltage at locations MCC and SE. Can >>> this be done: >>> >>> I have several questions: >>> >>> 1. I assume that the voltage source in your model assumes it >>> delivers infinite current. That is., an ideal voltage source. This >>> is not true in practical systems. We have a Utility service feeding >>> a transformer. The utility provides a maximum short circuit current >>> at a certain voltage. The utility delivers voltage with a maximum >>> current. The transformer changes the voltage but has an internal >>> impedance. In your model the transformer does not have primary or >>> secondary voltage levels, only the voltage ratio.It ou can I model >>> this utility - transformer combination? Well, the maximum voltage (usually VA) in a transformer has something to do with the iron saturation in a transformer, the ideal inductor doesn't deal with this. You could also give the coupled inductors a try. >>> >>> I assume that I entered the values of resistance in a correct way my >>> specifying m Ohm representing milli Ohms. Is this correct.? Correct, you don't need the space in between m and Ohm, but it is alright. >>> >>> It would be great I could use this program in my grounding seminars. >>> But if this program is not the adequate, do you know of circuit >>> simulator program more geared to power? I have SKM software but I >>> can’t draw single phase diagrams like the above and I can not use >>> SKM for this grounding analysis. I think qucs is quite powerful, but like in any simulator you have to chose the right models. Like for your motor you are using a resistor, you probably also want to have at least an inductive component in there. There may be simulators available that have motor models available but I am not aware of them. Just play around and chose which simulator fits you better. >>> >>> Thanks. >>> >>> >>> >>> >> > ```