Lightning Transients - John Dunn, Consultant, Ambertec, P.E., P.C.

Document RTCA/DO-160 Section 22 has some voltage and current waveforms to represent lightning induced transient events. Those waveforms are sketched below and descriptive algebraic equations of each waveform are shown which may be useful in transient protection analyses.

 

Text can't be copied from the above image so the text below is provided for that purpose:

Waveform 1 and Waveform 4 with TUSEC as time expressed in microseconds.

I=109.34*(1-EXP(-TUSEC/1.561))*EXP(-TUSEC/88.19)

 

Waveform 2 with TFALL as the time beyond T1 expressed in microseconds.

V=100*(1-(1-EXP(-TFALL/5.1559))*(1+EXP(-TFALL/(1.4*5.1559)))) (With lesser undershoot.)

V=100*(1-(1-EXP(-TFALL/6.2131))*(1+EXP(-TFALL/(1.8*6.2131)))) (With greater undershoot.)

 
Waveform 3 with the time T expressed in seconds and F expressed in Hz.

I=100*SIN(2*PI*F*T)*EXP(-T/(2.89/F))

I=100*SIN(2*PI*F*T)*EXP(-T/(13.9/F))

 

Waveform 5A with TUSEC as time expressed in microseconds.

I=216.4*(1-EXP(-TUSEC/29))*EXP(-TUSEC/83)

 

Waveform 5B with TUSEC as time expressed in microseconds.

I=109.7*(1-EXP(-TUSEC/12))*EXP(-TUSEC/650)

Comments

[John Dunn]

These waveforms are available in chart form from HV Technologies, Inc. at emcsales@hvtechnologies.com. There is additional information in that chart as well.

One way I've used equations like these was to derive a text file of amplitude values and times, import that table into a Multisim SPICE arbitrary waveform generator and then use that generator to drive a circuit of interest to examine what would happen.

The other way was to include such waveform equations in recursive differential equations analyses. See:

http://licn.typepad.com/my_weblog/2011/02/using-recursive-differential-equations-john-dunn-consultant-ambertec-pe-pc.html#more

[Terry Graves]

John,
In your opinion, do "Porcupine" devices disipate lightning feelers or is that just wishful thinking?
Terry

[John Dunn]

From directi information, Terry, I have no idea. My gut level intuition would be "no" however, if I understand the device correctly. All kinds of sharp points would each be a concentration site for e-field.

[Harshul Gupta]

Terry - in my experience, streamer inhibition is possible. I would recommend you this URL: http://www.lightningelectrotechnologies.com/GHX/icon-VideoSection.png
The inventor talks about the Glow Mode Corona and Streamer Mode Corona which would make the Porcupine devices not effective for streamer inhibition, however the inventor proposes and displays a technology that definitely delivers "Streamer Inhibition".