What you said below seems reasonable, for a point source of radiation. If
you go to:
http://www.emctest.com/productpage.cfm?model=3121Cproducttype=Antennas
you can see that the 3 and 10 meter antenna factors for tuned dipoles are
close but not equal. This is the far field/near field issue. I
Hi Tom:
Is it permitted to use PTC as an overcurrent protective device
for power sources not inherently limited?
I don't have EN60950-1 here, but I remember it must be a fuse
or other non-autoreset device.
I said:
The trick is to determine if your test houses can
-Original Message-
From: am...@westin-emission.no [mailto:am...@westin-emission.no]
Sent: Wednesday, September 04, 2002 12:35 AM
To:EMC-PSTC
Subject: Vehicle - EMC shielding effect
Sensitivity: Confidential
Hi all,
What is the EMC shielding effect of a military armoured
I read in !emc-pstc that Gregg Kervill gr...@test4safety.com wrote (in
002b01c25428$4985b680$7100a8c0@MENHADEN) about 'electric strength
test' on Wed, 4 Sep 2002:
This would suggest that it would be better to
double/reinforce insulate the mains against
earth, in which case SELV could be earthed.
We don't disagree that at 30 Mhz, 3 meters is too close for a dipole. It's
too big for the distance, even if we are often compelled to use it that
way.
In this case, however, an AF of 5 dB puts the dipole at about 50 MHz -- 3
meters long. The distance to the source, 3 meters at the dipole's
Folks,
I've been searching all afternoon for recent news on halogen flame
retardent regulation in the EU. I'm beginning to think that other than
brominated flame retardents, there really is not much current concern and
the risks involved with accelerated fire spread (over that with halogenated
I don't disagree that the biconical and tuned dipole should give the same
result if they are in the far field of the EUT. I am saying that at 30 MHz
you are not in the far field and therefore I would expect to get different
answers from each antenna. Just look at the angle subtended by the 5
Hello Ken and Amund,
in the explanations below I miss a comment re the influence of the
transition regio between near field and far field, which starts at
Lambda/4.
Is it correct to make the assumption that the E field will be unaltered,
or does one have to make a frequency dependent correction
AMund,
That's correct. One adds the antenna factor in dB to measured dBuv to get
the field.
Ken Javor points out that you do need to worry about being in the
plane-wave, far-field. 5 dB dipole AF is typical of around 50 MHz, where a
three meter distance is enough to be in the far field - for a
-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Rich Nute
Sent: Tuesday, September 03, 2002 7:31 PM
To: soundsu...@aol.com
Cc: Product Safety Technical Committee
Subject: Re: electric strength test
Hi Greg:
Why
Hello Mark,
Which statements in particular are you looking for? There are a number of legal
documents (a few of the Korean ones are available in English, albeit
unofficial translations) dealing with certification requirements for both
these countries, depending on the type of product in
Most armored vehicles on which I have performed or witnessed EMC tests (AAV,
LAV, M60, M1), were (as are all UUTs) very configuration-dependent,
resulting in much difficulty building consistent data sets.
There were many combinations of hatch orientation, system installations, and
external
There is no mil-spec requirement for shielding effectiveness of
platforms/vehicles, but expected attenuation can be deduced by inspection of
MIL-STD-461D/E RE and RS requirements. The Air Force shows a 20 dB spread
between RS103 requirements for equipment mounted inside vs. outside a metal
The equation is right but it doesn't reflect reality. Unless the 40 dBuV/m
was measured with a half-wave dipole, don't expect to measure it with a
half-wave dipole. Most VHF measurements are made with a biconical which is
an electrically short, fat dipole below 80 MHz. That means the field
Hi all
EN 60950:2000 paragraph 6.3 talks about the max. current in telecom
cables. If you don't describes anything about cable AWG you are only
allowed to load the cables with 1.3 A. If you want to load with more you
shall make a note in the installation manual which AWG you shall use.
I think
Hello Chun -
Could you identify the legal documents from the governments for Korea and
China that have these statements? I would be interested in understanding a
bit further. Thanks.
Regards,
Mark F. Gill
Sr. Engineer
C-MAC Design Corporation, A Solectron Company
4222 Emperor Blvd,
Hi all,
Assume you have a device which radiates 40dBuV/m @ 30MHz, measured at 3m
distance. In real life this device is placed adjacent (3m) to a dipole
antenna (radio receiver system 30-80MHz). Lets say the dipole antenna factor
is 5dB.
What is expected to measure on the antenna terminal ?
Can
Hi all,
What is the EMC shielding effect of a military armoured vehicle (no windows,
no cabling from inside to outside, ABC protected, etc) ? Is it 10dB or
15.5dB ? ha-ha :) Well, I assume you could pick a number
between 0-100 dB, because the EMC shielding effect will depend on a
I read in !emc-pstc that Kevin Richardson kevin.richard...@ieee.org
wrote (in nebbihdflagbliikmlbkkebkdlaa.kevin.richard...@ieee.org)
about 'CE Compliance of Professional Lighting Dimmer Box' on Wed, 4 Sep
2002:
For safety, someone has suggested the following may apply but I am a bit
dubious
Hi All,
Well, I have been writing again. This month my article is on voltage
measurements.
Voltage measurements can give misleading results with some measurements
yielding a result that appears nowhere in the circuit of interest! This
month's Technical Tidbit at http://emcesd.com is titled
On Tue, 3 Sep 2002 15:49:43 -0700 (PDT),
Rich Nute ri...@sdd.hp.com wrote:
If you use a PTC, then your output need not necessarily be
considered inherently limited. In this case, your
maximum output current is 100 amps and your maximum VA is
250, i.e., 25 amps (with the PTC shorted).
I am trying to identify the requirements for a professional lighting
dimmer/distribution type stand-alone box which incorporates a 3 phase star
(neutral required) with earth type power supply. The box provides the
following outputs:
- multiple (10A) dimmer circuits (std mains type outlets)
-
Hello from San Diego:
One of our subscriber colleagues has pointed out that
my assertion that Europe uses yellow as the color of
the earthing wire is incorrect.
I recall when the green-yellow was agreed to for
power cords and internal equipment wiring. My
recall was that both yellow and
Hi Greg:
Why does True SELV require basic insulation
between SELV and earth?
What is the hazardous voltage source, and what
is the current path through the body if that
basic insulation should fail?
I believe (and I could be wrong) that it's a
I never cease to be amazed by the things I don't know, but I am
afraid that (so far as I am aware) the use of yellow only is not an
acceptable alternative to green and yellow so far as protective or
equipotential bonding conductors are concerned in any of the European
equipment or building
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in
200209031926.maa24...@epgc264.sdd.hp.com) about 'Green/Yellow Earthing
Leads' on Tue, 3 Sep 2002:
In Europe, the earthing conductor in building
wiring is yellow.
[snip]
In Europe, power cord and equipment earthing
conductors may be
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