Actually, the EFT test pre-dates the IEEE reference. IEEE included a
reference to IEC 801-4 in the earlier IEEE 587 document, which has now
become ANSI/IEEE C62.41 (now reissued as a 2002 document as a Trilogy:
C62.41, C62.42, and C62.45). In the 70's, EFT tests were being conducted in
Europe using spark gap generators, or what were called showering arc
generators. The EFT burst as we know it grew out of this.
Unfortunately, neither the current IEC 61000-4-4 nor the older IEC
801-4-1988 contain any direct references for supporting material. In
re-casting 61000-4-4 towards a revision, I looked for supporting documents
but found only indirect information: a memo referring to work done by ABB in
Sweden to define the transients; anecdotal information regarding the
frequencies of real EFT to be in the MHz region, and a report from ABB
Center in Mannheim of 1991 talking about the problems with EFT generators
duplicating real field failures.
I also have a New Work Item Proposal of 2000 from the Swedish National
Committee. It contains data showing field measurements of EFT frequencies to
be in the hundreds of MHz (vs. 2.5kHz and 5kHz in the current standard), and
amplitudes of 1.5kV to 3.5kV. They propose burst frequencies from 400kHz to
25MHz and burst packets starting with low voltages at high repetition rates,
ramping up to higher voltages at lower repetition rates.
Some of this is now being dealt with in a proposed revision to IEC
61000-4-12, about to be circulated as a CDV, and will be reviewed by the
SC77B Working Group 11 in the September meeting in Spain.
Probably not useful info, but that's about it.
Best Regards,
Michael Hopkins
Manager, EMC Technologies
Thermo Electron
Control Technology Division
EMC ESD Simulation Solutions
One Lowell Research Center
Lowell, MA 01852
Tel: +1 978 275 0800 ext. 334
Fax: +1 978 275 0850
michael.hopk...@thermo.com
One Thermo, committed to integrity, intensity, innovation involvement
From: Pat Lawler [mailto:pat.law...@verizon.net]
Sent: Wednesday, June 04, 2003 10:55 AM
To: EMC-PSTC
Subject: Re: Electrical Fast Transient (EFT) and the Real World
On Mon, 02 Jun 2003 16:51:47 -0400, Stephen Irving
sirv...@lutron.com wrote:
We are investigating the Electrical Fast Transient (EFT) test as detailed
in IEC/EN 61000-4-4. I am looking for some experience/advise with this test.
My understanding is that the IEC created this test to standardize fast line
transient tests, such that a single repeatable test could be performed. As
such, I am having a hard time finding information regarding the naturally
occurring voltages and frequencies of these events. We are trying to expand
the prescribed test into a real-world, worst case test. Does anyone have
any experience or related documents that may help?
Also, the test is prescribed to have a period of 300ms (15 line cycles at
50Hz). We are in the US, and are running the test at 60Hz (which does not
work out to an even number of cycles - the beginning of the transient moves
in time). Does anyone know if the test should be altered to provide a
repeatable transient, or if there is a reason to leave it at 60Hz.
I look forward to your comment - this is an interesting one! As always,
thanks for your help.
Best regards,
Steve Irving
It looks like the EFT test was copied from an older IEEE document
circa 1980. Take a look at specification IEEE C62.41, Recommended
Practice on Surge Voltages in Low-Voltage AC Power Circuits.
Besides defining the waveshape of various transient waveforms
(100kHz ringwave, Combination wave, 5n/50ns EFT, 10/1000us wave, 5kHz
ringawave), it also has a section describing transients found in the
United States.
Pat Lawler pat.law...@verizon.net
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