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V and I not in phase at resonance Frequency in RLC network?
Hi,
Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? Or why this Problem is showing up? Thanks to anyone reading this and especially to those who post answers. D. Stutzer |
On 14 Oct 2003 11:38:29 -0700, (Diego Stutzer)
wrote: Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? Or why this Problem is showing up? Thanks to anyone reading this and especially to those who post answers. D. Stutzer The impedance should be R + jwL + 1/(jwC) d _____________________________ http://www.pearce.uk.com |
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Don Pearce wrote:
The impedance should be R + jwL + 1/(jwC) 1/j = j/j*j = j/-1 = -j -j/wC = 1/jwC -- Pawel Stobinski Republic of Poland |
Don Pearce wrote:
The impedance should be R + jwL + 1/(jwC) 1/j = j/j*j = j/-1 = -j -j/wC = 1/jwC -- Pawel Stobinski Republic of Poland |
John Fields schrieb in im Newsbeitrag: ... On 14 Oct 2003 11:38:29 -0700, (Diego Stutzer) wrote: Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? --- 1 f = ------------- 2pi(sqrt(LC)) -- John Fields WOW!! Thank you soo much. The world is sound and the laws of physics apply again. I just confused w (omega) and f. Best Regards D. Stutzer |
John Fields schrieb in im Newsbeitrag: ... On 14 Oct 2003 11:38:29 -0700, (Diego Stutzer) wrote: Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? --- 1 f = ------------- 2pi(sqrt(LC)) -- John Fields WOW!! Thank you soo much. The world is sound and the laws of physics apply again. I just confused w (omega) and f. Best Regards D. Stutzer |
The impedance should be R + jwL + 1/(jwC)
You sure?, how do the j parts cancel at resonance if they are both added? |
The impedance should be R + jwL + 1/(jwC)
You sure?, how do the j parts cancel at resonance if they are both added? |
Which voltage and which current? Clearly the voltage across the
capacitor will always be pi/2 relative to the current in that capacitor, and the same (but opposite sign) for an inductor. Also, are you doing an AC or a transient analysis? If transient, are the transients settled, are you really on the resonance frequency, and are you simulating with sufficient time resolution? Oh, and I'm not quite sure what you mean by "lambda/4" phase shift. Is that degrees or radians, and what's lambda? Cheers, Tom (Diego Stutzer) wrote in message . com... Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? Or why this Problem is showing up? Thanks to anyone reading this and especially to those who post answers. D. Stutzer |
Which voltage and which current? Clearly the voltage across the
capacitor will always be pi/2 relative to the current in that capacitor, and the same (but opposite sign) for an inductor. Also, are you doing an AC or a transient analysis? If transient, are the transients settled, are you really on the resonance frequency, and are you simulating with sufficient time resolution? Oh, and I'm not quite sure what you mean by "lambda/4" phase shift. Is that degrees or radians, and what's lambda? Cheers, Tom (Diego Stutzer) wrote in message . com... Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? Or why this Problem is showing up? Thanks to anyone reading this and especially to those who post answers. D. Stutzer |
Don Pearce wrote: On 14 Oct 2003 11:38:29 -0700, (Diego Stutzer) wrote: Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. -j/wc= 1/jwc |
Don Pearce wrote: On 14 Oct 2003 11:38:29 -0700, (Diego Stutzer) wrote: Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. -j/wc= 1/jwc |
Multiply top and bottom of 1/jwC by j (This does not change its value) and
you get 1/jwC = minus j/wC. Back to school with your algebra. |
Multiply top and bottom of 1/jwC by j (This does not change its value) and
you get 1/jwC = minus j/wC. Back to school with your algebra. |
On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards"
wrote: Multiply top and bottom of 1/jwC by j (This does not change its value) and you get 1/jwC = minus j/wC. Back to school with your algebra. His algebra looks perfectly fine to me. But as others have pointed out, he's left the 2pi out. |
On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards"
wrote: Multiply top and bottom of 1/jwC by j (This does not change its value) and you get 1/jwC = minus j/wC. Back to school with your algebra. His algebra looks perfectly fine to me. But as others have pointed out, he's left the 2pi out. |
"budgie" wrote in message ... On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards" wrote: Multiply top and bottom of 1/jwC by j (This does not change its value) and you get 1/jwC = minus j/wC. Back to school with your algebra. His algebra looks perfectly fine to me. But as others have pointed out, he's left the 2pi out. ------------------------------------------ Yes. I apologise for my remark about school. I gained the incorrect impression from the previous replies. The w in wC stands for omega = 2*Pi*F, the angular frequency. |
"budgie" wrote in message ... On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards" wrote: Multiply top and bottom of 1/jwC by j (This does not change its value) and you get 1/jwC = minus j/wC. Back to school with your algebra. His algebra looks perfectly fine to me. But as others have pointed out, he's left the 2pi out. ------------------------------------------ Yes. I apologise for my remark about school. I gained the incorrect impression from the previous replies. The w in wC stands for omega = 2*Pi*F, the angular frequency. |
On Tue, 14 Oct 2003 19:56:43 +0100, Don Pearce, said...
On 14 Oct 2003 11:38:29 -0700, (Diego Stutzer) wrote: Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? Or why this Problem is showing up? Thanks to anyone reading this and especially to those who post answers. D. Stutzer The impedance should be R + jwL + 1/(jwC) d _____________________________ http://www.pearce.uk.com now that were all done playing with j... Z = sqrt[R^2 + (jwL)^2 - (1/jwC)^2] = sqrt[R^2 + (jwL)^2 + (j/wC)^2] this is scary ****. mike |
On Tue, 14 Oct 2003 19:56:43 +0100, Don Pearce, said...
On 14 Oct 2003 11:38:29 -0700, (Diego Stutzer) wrote: Hi, Well, I'm really confused. I simulate a simple serial R-C-L-Network (all in series). As far as I know the total (input-)Impedance of the network is: Z = R + jwL - j/(wC) resp. the resonance frequency (where Zin=R) is 1/sqrt(L*C). At resonance frequency, the Impedance should be real and therefore in my hummel opinion Voltage and Current schould be in phase. The funny thing is, when i build up such a network in Schematics (Cadence PSD 14.1/Orcad 9.2) and simulate it with the PSpice A/D Simulator, the current is displaced (relative to the voltage) about lambda/4 - obviously not in phase!? Can anyone tell my where I made a mistake? Or why this Problem is showing up? Thanks to anyone reading this and especially to those who post answers. D. Stutzer The impedance should be R + jwL + 1/(jwC) d _____________________________ http://www.pearce.uk.com now that were all done playing with j... Z = sqrt[R^2 + (jwL)^2 - (1/jwC)^2] = sqrt[R^2 + (jwL)^2 + (j/wC)^2] this is scary ****. mike |
On Wed, 15 Oct 2003 02:43:27 +0000 (UTC), Reg Edwards, said...
"budgie" wrote in message ... On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards" wrote: Multiply top and bottom of 1/jwC by j (This does not change its value) and you get 1/jwC = minus j/wC. Back to school with your algebra. His algebra looks perfectly fine to me. But as others have pointed out, he's left the 2pi out. ------------------------------------------ Yes. I apologise for my remark about school. I gained the incorrect impression from the previous replies. The w in wC stands for omega = 2*Pi*F, the angular frequency. now that were all done playing with j... don't forget Z = sqrt{R^2 + [(wL) - (1/wC)]^2]} and Z(s) = R + Ls + 1/Cs which is just plain easier to deal with 'til you need to journey back into time domain land. no need to leave it f(t) for this deal, though. all that j stuff... that was scary ****. so easy to make a mistake. swapping w and f is another good one. only works for f/f stuff. mike |
On Wed, 15 Oct 2003 02:43:27 +0000 (UTC), Reg Edwards, said...
"budgie" wrote in message ... On Wed, 15 Oct 2003 02:03:05 +0000 (UTC), "Reg Edwards" wrote: Multiply top and bottom of 1/jwC by j (This does not change its value) and you get 1/jwC = minus j/wC. Back to school with your algebra. His algebra looks perfectly fine to me. But as others have pointed out, he's left the 2pi out. ------------------------------------------ Yes. I apologise for my remark about school. I gained the incorrect impression from the previous replies. The w in wC stands for omega = 2*Pi*F, the angular frequency. now that were all done playing with j... don't forget Z = sqrt{R^2 + [(wL) - (1/wC)]^2]} and Z(s) = R + Ls + 1/Cs which is just plain easier to deal with 'til you need to journey back into time domain land. no need to leave it f(t) for this deal, though. all that j stuff... that was scary ****. so easy to make a mistake. swapping w and f is another good one. only works for f/f stuff. mike |
On Tue, 14 Oct 2003 21:30:18 +0200, "Pawel Stobinski"
wrote: Don Pearce wrote: The impedance should be R + jwL + 1/(jwC) 1/j = j/j*j = j/-1 = -j -j/wC = 1/jwC Quite right - the unusual format fooled me. d _____________________________ http://www.pearce.uk.com |
On Tue, 14 Oct 2003 21:30:18 +0200, "Pawel Stobinski"
wrote: Don Pearce wrote: The impedance should be R + jwL + 1/(jwC) 1/j = j/j*j = j/-1 = -j -j/wC = 1/jwC Quite right - the unusual format fooled me. d _____________________________ http://www.pearce.uk.com |
On Wed, 15 Oct 2003 06:11:13 GMT, Active8
wrote: now that were all done playing with j... don't forget Z = sqrt{R^2 + [(wL) - (1/wC)]^2]} and Z(s) = R + Ls + 1/Cs which is just plain easier to deal with 'til you need to journey back into time domain land. no need to leave it f(t) for this deal, though. all that j stuff... that was scary ****. so easy to make a mistake. Especially so given the limited typography of this particular medium. I suspect few of us would have a problem if we could only view these formulae in a suitably appropriate typeface!!! -- "Windows [n.], A thirty-two bit extension and GUI shell to a sixteen bit patch to an eight bit operating system originally coded for a four bit microprocessor and produced by a two bit company." |
On Wed, 15 Oct 2003 06:11:13 GMT, Active8
wrote: now that were all done playing with j... don't forget Z = sqrt{R^2 + [(wL) - (1/wC)]^2]} and Z(s) = R + Ls + 1/Cs which is just plain easier to deal with 'til you need to journey back into time domain land. no need to leave it f(t) for this deal, though. all that j stuff... that was scary ****. so easy to make a mistake. Especially so given the limited typography of this particular medium. I suspect few of us would have a problem if we could only view these formulae in a suitably appropriate typeface!!! -- "Windows [n.], A thirty-two bit extension and GUI shell to a sixteen bit patch to an eight bit operating system originally coded for a four bit microprocessor and produced by a two bit company." |
R + jwL + 1/(jwC)
= R + jwL -j/(wC) so at resonance wL=1/(wC) ie w=1/sqrt(LC) Chris "Michael" wrote in message om... The impedance should be R + jwL + 1/(jwC) You sure?, how do the j parts cancel at resonance if they are both added?+ |
R + jwL + 1/(jwC)
= R + jwL -j/(wC) so at resonance wL=1/(wC) ie w=1/sqrt(LC) Chris "Michael" wrote in message om... The impedance should be R + jwL + 1/(jwC) You sure?, how do the j parts cancel at resonance if they are both added?+ |
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On Wed, 15 Oct 2003 09:18:51 +0100, Paul Burridge, said...
On Wed, 15 Oct 2003 06:11:13 GMT, Active8 wrote: now that were all done playing with j... don't forget Z = sqrt{R^2 + [(wL) - (1/wC)]^2]} and Z(s) = R + Ls + 1/Cs which is just plain easier to deal with 'til you need to journey back into time domain land. no need to leave it f(t) for this deal, though. all that j stuff... that was scary ****. so easy to make a mistake. Especially so given the limited typography of this particular medium. I suspect few of us would have a problem if we could only view these formulae in a suitably appropriate typeface!!! what pre tell, is a typeface that would make it hard? wing-dings? i admit, even in HTML with arial or fixed-pitch, where you have sub and super tags and greek letter codes, you can't do much. i tried a few free math notation tools for HTML and wasn't happy. plus you need a plugin for most if not all. W^3C has a standard. i'd like to see more math capabiliies in browsers. we could attach formulae without violating the no bianaries rule. of course microshaft and standards will probably never be seen in the same line of code. i still don't see why text based math legibility is font dependant. i see i could have eliminated some clarifying parens by - - | 2 1 2 | sqrt | R + ----- | or a 1/2 power instead of sqrt | jwC | - - created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de does that also foul up? brs, mike |
On Wed, 15 Oct 2003 09:18:51 +0100, Paul Burridge, said...
On Wed, 15 Oct 2003 06:11:13 GMT, Active8 wrote: now that were all done playing with j... don't forget Z = sqrt{R^2 + [(wL) - (1/wC)]^2]} and Z(s) = R + Ls + 1/Cs which is just plain easier to deal with 'til you need to journey back into time domain land. no need to leave it f(t) for this deal, though. all that j stuff... that was scary ****. so easy to make a mistake. Especially so given the limited typography of this particular medium. I suspect few of us would have a problem if we could only view these formulae in a suitably appropriate typeface!!! what pre tell, is a typeface that would make it hard? wing-dings? i admit, even in HTML with arial or fixed-pitch, where you have sub and super tags and greek letter codes, you can't do much. i tried a few free math notation tools for HTML and wasn't happy. plus you need a plugin for most if not all. W^3C has a standard. i'd like to see more math capabiliies in browsers. we could attach formulae without violating the no bianaries rule. of course microshaft and standards will probably never be seen in the same line of code. i still don't see why text based math legibility is font dependant. i see i could have eliminated some clarifying parens by - - | 2 1 2 | sqrt | R + ----- | or a 1/2 power instead of sqrt | jwC | - - created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de does that also foul up? brs, mike |
....snip
i still don't see why text based math legibility is font dependant. i see i could have eliminated some clarifying parens by - - | 2 1 2 | sqrt | R + ----- | or a 1/2 power instead of sqrt | jwC | - - created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de does that also foul up? brs, mike Oh, Mike. That's ugly!! Strangely, when I see it in this window I type replies in, it's much clearer! Hey, ho. I agree with you about viewing these things in browsers... always hard. For my money, the first ones in this chain were as good as any I've seen |
....snip
i still don't see why text based math legibility is font dependant. i see i could have eliminated some clarifying parens by - - | 2 1 2 | sqrt | R + ----- | or a 1/2 power instead of sqrt | jwC | - - created by Andy´s ASCII-Circuit v1.22.310103 Beta www.tech-chat.de does that also foul up? brs, mike Oh, Mike. That's ugly!! Strangely, when I see it in this window I type replies in, it's much clearer! Hey, ho. I agree with you about viewing these things in browsers... always hard. For my money, the first ones in this chain were as good as any I've seen |
all that j stuff... that was scary ****. so easy to make a mistake. swapping w and f is another good one. only works for f/f stuff. mike I get a bit scared of all the j's too, I prefer polar. Usually you want a magnitude and angle in the end result anyway. |
all that j stuff... that was scary ****. so easy to make a mistake. swapping w and f is another good one. only works for f/f stuff. mike I get a bit scared of all the j's too, I prefer polar. Usually you want a magnitude and angle in the end result anyway. |
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