John, I have transmitter that transmits on a VHF Frequency about 2 minutes
after I shut the car off. A number of setups allow a person to use a hand
held device to access a higher powered transceiver that is in the car. It's
fairly common setup for highway patrol vehicles, due to distance from the
control points.
Jim
On July 24, 2023 6:04:13 PM John Woodgate <j...@woodjohn.uk> wrote:
There are, but 20 V/m still is a very high value. One wouldn't expect a
transmitter to be used in a car while it is on charge.
On 2023-07-24 22:57, Jim Bacher, WB8VSU wrote:
Wi-Fi and cell phones are not the only transmitters near cars. There are
police, fire and ham radio transceivers in cars. Some of which are on gain
antennas and can be remotely accessed to transmit. Not to mention hand held
transceivers that might walk by.
Jim, WB8VSU
On July 24, 2023 5:51:27 PM Brian Gregory <brian_greg...@netzero.net> wrote:
The reference for 20 V/m to EV chargers comes from UL 2231-2. This is not
a medical standard, but Annex A does call out the medical standard
60601-1-2 as a reference, as well as CENELEC 50204. We can't figure out
why; cell phones produce less than half that, and our WiFi transmitter is
probably representative, and is rated well under 1 W. I could see a higher
immunity standard as needed for commercial environments, say in a bank of
4-5 chargers.
Following along in 61000-4-3, we agree with John that residential
applications are clearly best matched to the definition for Class 2
environment, and the table in Clause 5 says the limits for Class 2
equipment is 3 V/m. 20 V/m does not show up in Clause 5 of 61000-4-3 for
any class.
So, I've should to reach out to a UL standards group and find out if this
is really necessary for residential applications. Our local lab can't do
more than 10, and an overseas affiliated lab is similarly limited. I'd
like to know were this requirement comes from. This is more a question
for EV Charging safety than a mainstream EMC question.
As a backup, I could request a comment to Ken's point is if they define the
peak of the modulation as 20 V/m. I don't know where these are defined.
Thanks for all the detailed replies!
Colorado Brian
720-450-4933
---------- Original Message ----------
From: John Woodgate <j...@woodjohn.uk>
To: Brian Gregory <brian_greg...@netzero.net>
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100
61000-4-3 is a Basic Standard. It does not specify test levels but
indicates possible test levels. You need to look in detail at Clause 5, but
look at these words:
Product committees shall select the appropriate test level for each
frequency range needing to be tested as well as the frequency ranges.
The residential environment is usually designated Class 2 (see Annex E of
the standard), which calls for 3 V/m.
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi
(340 - 245 BC)On 2023-07-21 17:44, Brian Gregory wrote:
Hello colleagues,
We are building EV Chargers for residential markets (not just US) and one
of the safety applicable standards is UL 2231-2. It calls out IEC
61000-4-3 for immunity testing parameters, which states a requirement for a
field strength of 20V/m. Our EMC expert says typically testing is "done at
3 Vrms, which is standard for most products in residential environments."
He can only test up to 10V, and we're hearing the same from an overseas lab
to whom our manufacturer refers.
Does FCC Part B have guidelines for field strength we can cite? Can some
offer this "DC guy" (aka, 60 Hz) a quick definition of what the 20V/m
represents?
I'm guessing 20 V/m is for higher density commercial applications, aka
charging stations, so we probably need an exception for residential.
Thank you!
Colorado Brian
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