From my reading on the subject, EN 60950 has different Safety Extra-Low Voltage
(SELV) limits for alternating current (AC) and direct current (DC) because the
human body reacts to them differently. AC makes your muscles contract, so you
tend to hang onto the source of the electric shock. DC
Cecil,
With that low a price point for the Photo Color Printer, unless you have a
completely weird interface you will not convince the FCC that it is an
industrial-use-only device. Some consumers will want to buy it, so you will
have to test to Class B. If you do a good job of designing the
Gary,
About 50% of our 100BASE-Tx cards require an additional 4-line common-mode choke
between the transformer-filter and the RJ-45 connector, to meet Radiated
Emissions limits with enough margin to satisfy our electromagnetic compatibility
(EMC) folks. So we snuggle all three components as
Jon,
My department has developed ten generations of Ethernet adapters (10BASE2,
10BASE-T, 100BASE-Tx) for IBM/Lexmark printers since 1990. We have looked at,
but so far have not used, integrated-magnetics connectors because we like having
the option of putting a common-mode choke in between
Alex,
I have written an article for Printed Circuit Design magazine on Designing
Electronic Equipment for ESD Immunity. Part 1 appeared on pages 18-26 of the
July 2001 issue (volume 18 number 7), and Part 2 will be in the August issue.
Printers and copiers can be quite nasty generators of
Neven,
To analyze the noise picked up by a wire that crosses a hole/slot in a shield,
look at:
[831] Lin, Guoxian, Electromagnetic Excitation of a Wire Crossing a Long Slot
in an Infinite Plane, Electromagnetic Compatibility 1989, Zurich,
Switzerland, Mar. 7-9, 1989, pp. 89-92.
[938] Nakano,
Paul,
I can't cite the exact clauses, because another engineer has borrowed all my
product safety standards, but UL 1950 has a deviation that calls for the primary
plug of a device to be rated for 125% of the device's rated input current. UL
applies this requirement to wall plugs, cordage, IEC
Martin,
I agree with Peter about designing even Class I (grounded) power supplies with
Class II (double-insulated) internal construction. Our Product Safety folks
require this, and have required it going back to our IBM Lexington days. The
grounding of wall outlets can not be trusted in many
Gary,
The best specifications that I have found are:
* South Korea 220V +/-10%, 60Hz +/-4%.
* North Korea 220V +6.8% -13.6%, 60Hz +0.0% -5.0%.
We use linecords with Schuko (CEE7 VII) plugs for both countries.
South Korea changed from a 110V 60Hz standard a few years ago. For several
years
Andrew Carson acar...@uk.xyratex.com wrote:
With phase connected to the phase terminal and neutral connected to the
neutral terminal, the international version was fine on the immunities. It
was only when the PSU was connected to a phase to phase supply, or the
phase and neutral reversed,
:
JRBARNES Mail)
Glyn,
I have submitted a 21-page article on Designing Electronic Equipment for ESD
Immunity to Printed Circuit Design magazine. In my literature search, I read
over 70 books and nearly 1300 articles/papers/standards/application notes on
Electrostatic Discharge (ESD) and related subjects
Glyn Garside(TUV) ggarside%us.tuv@interlock.lexmark.com on 04/21/2001
12:57:30 AM
Please respond to Glyn Garside(TUV)
ggarside%us.tuv@interlock.lexmark.com
To: Douglas C. Smith doug%emcesd@interlock.lexmark.com
cc: emc-pstc%ieee@interlock.lexmark.com,
The interpretation that IBM/Lexmark's safety folks have always given me is that
Pollution Degree 1 applies to sealed units such as the inner layers of
multilayer Printed Circuit Boards (PCB's) or potted modules.
John Barnes Advisory Engineer
Peter,
I looked through some of my books last night and this morning, and found
suggested spacings of:
* Greater than 20mm, 8.4mm, 5mm, or 10mm between circuits and:
- Points that a person could touch.
- Ungrounded metal parts that a person could touch.
* Greater than 2.2mm, 0.5mm,
Dwight,
According to Keytek Instrument Corp.'sPulsed EMI Handbook the use of
crossed-vane ESD simulators is covered by:
* ANSI C63 (searching the Internet led me toAmerican National Standard
Guide for Electrostatic Discharge Test
Methodologies and Criteria for Electronic
Jim, Daniel,
CEE 7-7, CEE 7/7, and CEE7 VII all refer to the 250V 16A Schuko plug commonly
used in Europe.
http://www.internationalconfig.com/config_chart/index.htmshows it at the
very top.
John Barnes Advisory
Engineer
Joe,
If the transmitting antenna (your product) and the receiving antenna were in
free space, you pretty much could assume that the radiation falls off at 1/r^2,
and thus use a 10.5dB correction factor between 10m and 3m measurements. (You
might have to worry about near-field effects and antenna
Terry,
I don't have a copy of EN 61000-6-2, but it sounds similar to the IBM Lightning
Surge Susceptibility (LSS) test that we do on our network adapters during
development/qualification. We LSS test all products that have:
* Cables going outdoors through surge protectors,
OR
*
A recent query on this forum asked about the relative effectiveness of
capacitors versus diodes for Electrostatic Discharge (ESD) protection. These
are just two of over 220 topics covered in my article, Designing Electronic
Equipment for ESD Immunity, which I wrote for Printed Circuit Design
Sandy,
IBM developed a Tabletop Electrostatic Discharge (ESD) test using a crossed-vane
ESD simulator, which we still use here at Lexmark to supplement IEC 61000-4-2
ESD testing. (We used to be IBM Lexmark.) I just ran across an article about
it a week ago in my research into methods of
Richard,
The term that I ran across many times while researching my book was optical
coverage-- as though you put a light bulb inside the shield and measured what
percentage of its light leaked out. The basic assumptions are:
1. Electric and magnetic fields inside the shield are totally blocked
Sergio,
A foil braid shield is quite common on high-speed cables. If a cable is
properly terminated and you don't have common-mode problems, most of its
radiated emissions will be from holes in the shield. Thus optical coverage,
the percentage of the shield's nominal area that is actually
Doug,
I ran into a problem in 1990 where we needed to add a primary fuse to a brick
power supply, without changing the circuit board or the case. We had two holes
in the circuit board where we could install a pigtailed fuse if we could find
one that would meet UL and SEMKO requirements. (SEMKO
Evangelos Tonas wrote an article EM Shielding Effectiveness of Low-cost
Architectural Shielding Materials that
appeared in the 1997 ITEM. This article is available on the web at
http://www.rbitem.com/ITEM_Publications/ITEM_Archives/I97art19.htm
Table 1 shows that chicken wire can achieve:
*
Gerald,
R. Kenneth Keenan's book Digital Design for Interference Specifications (Vienna,
Virginia: The Keenan Corporation, 1983) has some excellent advice for doing
developmental tests in chapter 6. He tells:
* How to do basic emissions tests using:
- An AM broadcast receiver.
- An FM
Rick,
We were developing the power supply for the Lexmark MarkNet Pro External Print
Servers. The power supply has a Y-cable with:
* A shrouded male IEC-320 sheet C14 connector on one end.
* A female IEC-320 sheet C13 plug.
* Soldered connections to the power supply card in the middle.
This
Kelly,
UL 1950 has a D1 (more restrictive) deviation in clause 3.2.1 than IEC 950:
Where equipment is intended to be connected to a source of supply by a power
supply cord, the attachment plug shall be rated no less than 125 percent of the
rated current of the equipment.
We got into a tussle
Kelly,
UL 1950 has a D1 (more restrictive) deviation in clause 3.2.1:
Where equipment is intended to be connected to a source of supply by a power
supply cord, the attachment plug shall be rated no less than 125 percent of the
rated current of the equipment.
UL's interpretation of attachment
Scott,
Have you tried looking at high-voltage chip capacitors? AVX for example offers
up to 18,000pF at 3000V and 5600pF at 4000V in a 3640 (nominally 0.36 x 0.40
footprint) package in an X7R dielectric. See pages 20 to 24 of the AVX
Multilayer Ceramic Chip Capacitor catalog.
The second half of my article, Designing Electronic Equipment for ESD
Immunity, has just been posted on Printed Circuit Design magazine's website.
The full article is now available on line:
* Part 1 athttp://www.pcdmag.com/story/OEG20010928S0122
* Part 2 at
Chris,
The 1996 World Electricity Supplies shows Australia as :
* 50Hz +/-0.1% frequency.
* 415/240V or 240/120V +/-6% for households.
* 415/240V or 480/240V +/-6% for commercial.
* 22kV, 11kV, or 6.6kV +/- 6% for industrial.
The 1991 edition of Electric Current Abroad shows:
* Albany,
Even now, correlation between 3 meters and 10 meters
is not guaranteed. And further, 3 meter to 10 meter
correlation is at least better (define better anyway
you wish) in the horizontal. Vertically it's terrible
(define terrible anyway you wish). At least in my
experience.
Doug,
In our 3m
What voltages can I expect on the Neutral (referenced to ground) line in
various countries
and connection systems? Is there a limit on how high the voltage may be, both
in normal and
fault conditions?
Moshe,
THE's booklet, World Electricity Supplies, lists the supply voltage,
frequency, and
Jess,
Most of my reference sources show the US as 120VAC +/-5% 60Hz +/-0.3% and
Argentina as 220VAC +/-10% 50Hz +/-2%. The 1996 World Electricity Supplies
shows:
* Charlotte, North Carolina as 120VAC +5-2.5% 60Hz +/-0.06%.
* Detroit, Michigan as 120VAC +4-6.6% 60Hz +/-0.2%.
* Los Angeles,
About a week ago one of the participants on this mailing list asked whether
equipment built in-house, for a company's
internal use, had to be safety and electromagnetic compatibility (EMC) tested.
I just started reading Tim Williams' book EMC for Product
Designers (second edition)
In another life, I was working for a EMC Test lab and we always used the
step by step procedure which was in the ESD Standard. We tested using this
procedure for years and we did encounter some products who failed at low
level ESD but had no problem at higher levels.
We wondered what to conclude
We are looking at Telephone Adapters, such as those made by TeleAdapt (
http://www.teleadapt.com/web/Catalogue/Index), to go from an RJ-11 plug to phone
jacks for the following countries:
(Embedded image moved to file: pic14566.pcx)
We have seen some adapters with UL, TUV, and CE marks. The
According to a table of Conversion Factors that I found on page 18 of the
December 1991 Electrical Manufacturing magazine, and keep stashed in my
dictionary here at work:
Watts * 3.413 = BTU's/hour
I use the maximum input power (wattage) that we have measured for a product in
its various
Donald,
The numeric suffixes key Table 0.1 to Figure 5A:
* OP1 through OP6 are all OPERATIONAL INSULATION (clause 1.2.9.1) which does
not provide protection from electric shock.
* B1 through B8 are all BASIC INSULATION (clause 1.2.9.2) which provides one
level of protection from electric shock.
Ron,
As a product developer, my major concern was getting the Lexmark Marknet XLe
approved worldwide. From my viewpoint HAR approval of the jumper cord was
equivalent to a bunch of individual country approvals. But Feller is still the
only manufacturer that I know of that makes IEC-320 jumper
Rich,
UL does not accept HAR cordage in the USA because the HAR
cordage does not meet the UL/ANSI standards for cordage.
Likewise UL/ANSI cordage does not meet HAR requirements.
Cordage that is Harmonized and UL/CSA-listed is rare but not impossible to find.
Feller offers these Universal
1. Is it true that plug adapters similar to those used by tourist are
not legal in most countries?
Back in 1991, when we were still part of IBM, I looked at getting a power supply
that would have an attached linecord with a CEE7 XVI(2) Europlug plug on it
for Europe. For the United Kingdom
Ron,
On the first Network Attach product I helped develop, the IBM 4033 External
Network Adapters, we wound up with 156 top bills-of-materials to cover three
basic models (announced in 1991):
* 4/16Mbps Token-Ring.
* 10BASE-T/10BASE2 Ethernet.
* 10BASE-T Ethernet).
We had:
* Two basic raw
Peter,
We used a HARSVT 3x18AWG 1.00mm2 Universal linecord from Feller on the
Lexmark MarNet XLe External Network Adapter. This had a Harmonized plus
UL/CSA-listed cordage. I can't find my Feller catalog right now, and their
website (http://www.feller-at.com/ ) doesn't say, but I
Gunter,
I discuss this on pages 71-72 of my book, Electronic System Design: Interference
and Noise Control Techniques, published by Prentice-Hall in 1987 (now out of
print, but you might find a copy by searching for the ISBN number
0-13-252123-7). A50-250nFcapacitor across each
John,
Or another example where different companies' equivalent parts are not
equivalent-- this is one that I ran into in 1977. I had designed a
Power-On-Reset (POR) circuit using a 555 timer, and had tested the circuit on a
solderless breadboard. I was being sneaky in my design, and used the
-- Virus Warning Message (on gemini3)
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