# [Scilab-users] calculate TRMS value in Xcos

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## [Scilab-users] calculate TRMS value in Xcos

 Dear all, by simulating an electrical power circuit I’d like to plot the voltage and the current over time, which is easy to perform by using the scope block. In addition to the signal recorded I’d like to calculate the TRMS value of the plotted current and voltage signal. Unfortunately Xcos does not include a TRMS block like e.g. Simulink do. Because I’m so far not so familiar with Xcos and Scilab I’d like to ask the community for support. Does anybody have a good idea or advise how to get the TRMS value of the recorded signal? Thanks and nice weekend Holger _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
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## Re: calculate TRMS value in Xcos

 RMS Value:  In a dynamic system simulation you can readily generate an instantaneous power value that can be recorded  simply by using a volts*current product or any other dimensionally equivalent product. If however you want to do some averaging of the power level then you must have a record of that instantaneous  value and do the averaging over the length of the record,  which your request implies you have and therefore implies a post processing operation. You can partition the record into whatever shorter lengths you want and generate true RMS values over those time segments. But beware, if the model is  simulating a fixed frequency  (e.g.50Hz) power system then the periods must be integer multiples of the cycle time. If you want a value that appears like a metered  value might appear then you can put the product term through a 1st order lag  (exponentially weighted effect)   G(s)=1/(1+sT)       // xdot=(1/T)*(Input- x); and imitate the behaviour of a meter. All you have to do is chose the "time constant",T, of the meter. e.g several cycles. The MATLAB (2017a)  Moving RMS includes the exponential weighting option and the true moving window version as well. I expect it could be replicated in XCOS with a SciLab function. Mike. ================== On 19/05/2017 05:51, Sachverständigenbüro Niedermaier Holger wrote: ```Dear all, by simulating an electrical power circuit I’d like to plot the voltage and the current over time, which is easy to perform by using the scope block. In addition to the signal recorded I’d like to calculate the TRMS value of the plotted current and voltage signal. Unfortunately Xcos does not include a TRMS block like e.g. Simulink do. Because I’m so far not so familiar with Xcos and Scilab I’d like to ask the community for support. Does anybody have a good idea or advise how to get the TRMS value of the recorded signal? Thanks and nice weekend Holger _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users ``` ```-- Dr.M.J.McCann,MJMcCann-Consulting ``` _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users
 I’m going to try both, the post simulation calculation and the 1st order lag.Thanks to you Mike and have a nice weekend.Am 19.05.2017 um 17:25 schrieb Michael J McCann <[hidden email]>: RMS Value:  In a dynamic system simulation you can readily generate an instantaneous power value that can be recorded  simply by using a volts*current product or any other dimensionally equivalent product. If however you want to do some averaging of the power level then you must have a record of that instantaneous  value and do the averaging over the length of the record,  which your request implies you have and therefore implies a post processing operation. You can partition the record into whatever shorter lengths you want and generate true RMS values over those time segments. But beware, if the model is  simulating a fixed frequency  (e.g.50Hz) power system then the periods must be integer multiples of the cycle time. If you want a value that appears like a metered  value might appear then you can put the product term through a 1st order lag  (exponentially weighted effect)   G(s)=1/(1+sT)       // xdot=(1/T)*(Input- x); and imitate the behaviour of a meter. All you have to do is chose the "time constant",T, of the meter. e.g several cycles. The MATLAB (2017a)  Moving RMS includes the exponential weighting option and the true moving window version as well. I expect it could be replicated in XCOS with a SciLab function. Mike. ================== On 19/05/2017 05:51, Sachverständigenbüro Niedermaier Holger wrote: ```Dear all, by simulating an electrical power circuit I’d like to plot the voltage and the current over time, which is easy to perform by using the scope block. In addition to the signal recorded I’d like to calculate the TRMS value of the plotted current and voltage signal. Unfortunately Xcos does not include a TRMS block like e.g. Simulink do. Because I’m so far not so familiar with Xcos and Scilab I’d like to ask the community for support. Does anybody have a good idea or advise how to get the TRMS value of the recorded signal? Thanks and nice weekend Holger _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users ``` ```-- Dr.M.J.McCann,MJMcCann-Consulting ``` _______________________________________________users mailing list[hidden email]http://lists.scilab.org/mailman/listinfo/users_______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users