Skip to main content
I
idarney1-Visitor
1-Visitor
May 23, 2016
Question

Transient Emission Model

  • May 23, 2016
  • 3 replies
  • 14273 views

 

The paper ‘Modelling the transient emission from a twin-conductor cable’ describes a test where a step pulse is applied to one end of an open-circuit cable. -  http://ietdl.org/t/ZKt6U 
The waveform of the differential-mode current delivered to the line was recorded. This was different from the waveform of a lossless line, since there were radiation losses. A circuit model was created to simulate the hardware-under-review and was subjected to transient analysis. Adjusting component values of the model enabled close correlation to be achieved between test results and model simulation. The process of creating the model provides an improved understanding of the mechanisms involved.

The ‘References’ section of the paper includes a link to the Mathcad worksheet which performs the calculations.

Comments will be welcome.

 

   

3 replies

L
LucMeekes23-Emerald IV
23-Emerald IV
May 23, 2016

I wonder what side-effect your first sheet (Fig2) runs on. I get this (in Mathcad 11):

The variable 'Ini' is undefined.

However, with this change it runs:

Luc

I
idarney1-VisitorAuthor
1-Visitor
May 24, 2016

Reply to LucMeekes

With Mathcad15, there was no need for me to pre-define the variable Ini. So I didn’t.

 

Ian Darney

 

A
AlanStevens19-Tanzanite
19-Tanzanite
May 24, 2016

"Comments will be welcome."

Not sure what sort of comments you are after, but I've looked at figure 2 in a somewhat different way.  The attached worksheet shows all the currents rather than just Ina.

(I used M15, which doesn't give the problem in the original figure 2 worksheet that Luc experienced, as it assigns initial values of zero by default)

Alan

PS I might have a look at the other figure worksheets if I get time.

I
idarney1-VisitorAuthor
1-Visitor
May 25, 2016

 

Response to Alan Stevens

It is possible to carry out bench tests on prototype equipment using a signal generator and oscilloscope to measure the susceptibility and emission characteristics of the equipment; then to create a circuit model to replicate that behaviour. The model can subsequently be used to predict the results of formal EMC Tests. Mathcad software is uniquely capable of carrying out all the calculations and presenting the results in a form suitable for peer review. One example is provided. The technique is capable of analysing any form of EMI coupling.

It may be that some of the statements in the paper could give rise to a sceptical response.

 

Thank you for your example of one way to develop the Time-Step Analysis program. I now have a copy on file.

  Ian Darney

 

-
-MFra-21-Topaz II
21-Topaz II
May 24, 2016

If the electric line is, for example, a coaxial cable, powered by a radiofrequency source,  it is demonstrated that there is absolutely no loss of energy for irradiation in the surrounding space.. In a two-wire line, much of the electromagnetic energy is confined between the two wires, in the surrounding space, however, the electromagnetic field is present. In the vicinity of the line is a reactive em field, while a small percentage of active power is radiated at a great distance in the surrounding space. This, I am sure that also applies to transient conditions.

Best regards

F.M.

I
idarney1-VisitorAuthor
1-Visitor
May 25, 2016

 

Response to F M

 

There is always radiation, even from a co-axial cable.

 

There is a fair correlation between behaviour in the frequency domain and that in the time domain. However, analysis of transients in the time domain leads to an improved understanding of the mechanisms involved.

 

Ian Darney

 

-
-MFra-21-Topaz II
21-Topaz II
May 26, 2016

My, it was a response based on intuition and not on an analytical demonstration. I'm sure that things are as you say. Thanks for your kind response.

Greetings

FM

Terms & ConditionsAccessibility statement