7;s just me and my 2 cents worth.
- Doug McKean
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nical hazard
- Heat hazard
- Radiation hazard
- Chemical hazard
...."
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"John Woodgate"
>
> If you are referring to my post, I plan to report that there is
> discussion here on the subject, and recount some of the points made.
> What we need is a very-widely accepted standard definition.
Thank you, John. We are here but to ser
John,
Extremely valid question since we are it seems in the
process of moving toward the world-wide concept
of 'one test, one approval'. I would be very surprised
if this very question has not been addresssed.
Regards, Doug McKean
--
azardous condition either during
normal operation or from a fault.
- Doug McKean
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To
The entire discussion is a Red Herring!
- Doug McKean
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To cancel your
of the remaining ferrites in a working
setup can sometimes telll you what's going on in
a setup that's modelled after a dipole.
Good luck ...
Regards, Doug McKean
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ide we get ...
dBuA = dBuV - 51.5 dBuV
But, I'm not so sure what's really being
demanded for the voltage measurements.
- Doug McKean
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V
, though.
The power supply will have different criteria with "Pass"
in 4-4 than your product.
- Doug McKean
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from Eq. (2)
>
> What am I missing?
The original intention of the calculations.
The first relation, dB = 10 log (aP2/P2) = 10 log (a)
is a "power" relation.
The second relation, dB = 10 log (aV2^2/V2^2) = 20 log (a)
is a "voltage relation
though, the internal procedures of some labs
may require you to retest maybe the emissions testing.
That I think follows Class B or residential equipment.
- Doug McKean
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Length of pipe and angle are just some of the things needed
to be considered. Otherwise, you could have a long enough
pipe and/or a pipe angle which could stop flow.
Try
http://www.efunda.com/formulae/fluids/calc_pipe_friction.cfm
Regards, Doug McKean
- Original Message -
From
Alarm - link is still active, an error has occurred.
Green Alarm - link is active, no errors.
White Alarm - link is inactive.
IOW, red and yellow alarms both have errors. But, they
are different because red means a link is down.
- Doug McKean
---
#x27;s anywhere near to what
you're asking is a Lucent standard.
Lucent X-19435 Minimum requirement of 500v for all
pins for modules operating at <200 MHz
I have no experience with this standard at all, so I have
no idea with what it's in reference to.
- Doug McKean
hall see or do. And that may not translate to a
purely statistical confidence level. And doing in trying to
obtain a statistical confidence level, the testing could very
well become completely unreasonable.
- Doug McKean
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it?
What subjects are to be restricted here?
I think it was most appropriate for John to ask the initial
question and I would support such discussions in the future.
And it is with my deepest apologies if this offends anyone.
It was not my intention.
- D
I have one I set up a while back as an alternate.
This is NOT a replacement of the PSTC group, please.
http://groups.yahoo.com/group/Compliance_Engineering
- Doug
- Original Message -
From: "Patrick Lawler"
To: "EMC-PSTC"
Sent: Wednesday, September 19, 2001 9:15 AM
Subject: Re: WTC
member the specifics of the 84 version
and I don't have any reference to it.
- Doug McKean
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both Canada and the US.
It's up to you, 6 of one or a six-pack of another ...
- Doug McKean
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to another of their customers,
you might want to give this some serious thought.
just my opinion ...
- Doug McKean
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overall (external) shield made of aluminum foil, but no shields on
individual
> wires or wire couples (as per 802.3 definition above).
Maintaining a characteristic impedence of a twisted pair
by shielding the individual wires of that twisted pair?
Something doesn't sound right.
- Doug McK
6-of-8 redundancy.
For topics in redundancy and general reliability calculations,
take a careful look at the following NASA website ...
http://tkurtz.grc.nasa.gov/srqa/dfr/dfr6.pdf
It has some great information.
Also is
http://www.cs.colostate.edu/~cs530/7reliability.pdf
- Doug
ormal operating temps of the devices internal
to your product. And that's all determined by very
careful measurements of the normal operating temps
of the product.
It is obviously much more complicated and involved
than what I've presented here. The semi
est asking your
NRTL test engineer.
- Doug McKean
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amage?
5. Is there some sort of history with these things
regarding failures and injuries to the users?
- Doug McKean
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The following is strictly opinion ...
I may be sticking my neck way out here, but it is my understanding
that any required manufacturing hi-pot test, with regard to UL-1950,
is contractual between the mfr of said device and the testing NRTL.
To my knowledge, there is no *requirement* within the s
tting
through the safety aspects that proved difficult.
This directly impacts the search effort for a
vendor to use up front before you even start
using it.
Make sure to consult your safety approvals engineer
at whatever NRTL you're using to fill you in on all
the d
t give you much overhead for 80C rated
wire. So, you might want to think long and hard about
using 80C rated wire for such an application. IMO, you'd
have to start with a minimum 105C rated wire.
8awg at 32 amps looks more like 23C rise above ambi
Thanks Sam.
I've been told that and the justification being
commercial versus residential zoning is not
as well defined in Europe as it is in the US.
Not sure how valid that explanation really is.
Anyone care to comment?
- Doug
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board.
Worked like a charm.
The level of testing was a result of the environment in which the
product would finally be used. Very uncontrolled environment.
- Doug McKean
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Do not rely on the word of some vendor employee with
regard to the safety criteria of the power supply.
Carefully read the CoA for that power supply.
If the CoA states compliance with the pertinent
standards as a Class I device, then there's nothing
you can do.
- Doug M
Bill Addiss wrote:
>
> Has anyone heard the term "Hertz Vibration" ?
> A friend had heard the term in a conversation somehow related to Circuit
> Breakers.
> I'm trying to help find the pieces to his puzzle.
> If this is a valid term, is there any info/papers on it We could read?
Must be somet
Interesting discussion.
I doubt such a thing, if it's ever made, would work at an OATS.
More likely a troubleshooting tool for an anechoic chamber.
There ambients are zilch and what you see is from your device.
Little break from the usual topics, but refreshing.
Thanks!
- Doug M
and another for magnetic fields which would
respond in various shades of blue.
- Doug McKean
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.
Now, if we could just train ourselves to sniff out some of
those pesky EMI problems ...
- Doug McKean
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half-wave rectifier.
Wasn't there a transformerless set accomplished
by caps somewhere in the distant past?
- Doug McKean
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mmercial,
or medical test equipment."
The important word is "digital". Why just digital? Does this mean
if a company makes analog industrial, commercial, or medical test
equipment, that equipment MUST be tested?
Regards, Doug McKean (slowly becoming more confused ...)
-
"Gorodetsky, Vitaly" wrote:
> Doug,
>
> You meant to say FCC exempt.
> Also, keep in mind that if equipment includes any additional
functions other
> than measurement than it shall be tested.
Sorry. Yes, you're correct.
What's the reason for the exemption from FCC testing?
- Doug
--
he first to break down >1000 Volts.
>
> Am I wrong?
Not really, but you might have a construction where
the clearance isn't straight line through air.
- Doug McKean
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Why or what is the reasoning behind test equipment
being exempt from all sorts of testing that's required
for other pieces of equipment?
- Doug McKean
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"John Woodgate" wrote:
> Doug McKean inimitably wrote:
>
> >One of the requirements in 1950 is to
> >ground any exposed metal parts accessible to the end user.
>
> Surely that applies only to Class I products? IF not, it would rule
out
> Class II and III pro
s applies to your product, but something to that
I think should be considered. If you're using a plastic housing
with conductive coating, that coating won't be enough since it's
not a reliable for grounding and is not accepted as a means
rored second is more in the style of a self
recovering type criteria than anything else.
- Doug McKean
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r the test. I would
suggest that your marketing people are the ones
with the final responsibility for this interpretation or
for what the customers are looking for with this
testing. Not you.
- Doug McKean
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27;t necessary, I doubt the
residents of mahogany row would approve it.
- Doug McKean
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hat's the need of a date code embedded in the serial
number when you have to look it up?
Also, the word "indication" may be interpreted any number of ways
also.
If you want to disect the wording, I'm sure it'll just get worse.
Regards, Doug McKean
---
am...@westin.org wrote:
>
> Hi all,
>
> Ventilation holes in a radio/tele cabinet,
> what are the maximum dimensions? According
> to EN60950, we cannot see any IP requirements?
>
> Any suggestions?
You're going to get any maximum dimension as long
as you follow all the guidelines for acce
l
testing of one version of a product (and thus ALL versions
of the product) is done and finished.
- Doug McKean
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ining compliance with the regulations. In this case,
the
builder is expected to employ good engineering practices to
meet
the specified technical standards to the greatest extent
practicable.
The provisions of Sec. 15.5 apply to this equipment.
"
- Do
ibility
to design simple common sense into everything that's made. It's
our responsibility for due diligence, good engineering practices,
safety, etc ... But if the product is being sold to the general
public,
remember the customer base can have as much as -2 full
ction
bouncing around the Northeast grid is what popped most
of the substations during the famous power outage in New
England during the 60's.
- Doug McKean
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don't want to be bothered.
Just my 3.1415 cents worth ...
- Doug McKean
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To cance
What's the accessibility to pins or traces or
anything carrying hazardous energy when
a power supply is pulled out?
- Doug
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Building your own machine doesn't constitute you
being a PC mfr. I think that's the reading here.
- Doug
- Original Message -
From: "Steve Grobe"
To: "'IEEE Forum'"
Sent: Wednesday, June 20, 2001 2:03 PM
Subject: RE: FCC + FCC = FCC?
>
> If you are so am I. As are a few dozen peopl
Re: FCC + FCC = FCC?Massey, Doug C. wrote:
>
> Just to further confuscate the issue - I once built my own home PC.
> I bought a box, motherboard, CPU, memory, variety of ISA cards, etc.
> It worked so well, I built a couple or three more for family and
friends,
> and sold them to those family and
boxes, and ship ...
- Doug McKean
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some blanket statement that said card can
in fact be in *any* type of PC construction.
- Doug McKean
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his
> specific fan is sufficient to keep the PWB from
> exceeding the allowable limit.
The mfr's p/n is not enough.
> 2. Control the fan by electrical ratings and physical
> size. The electrical ratings (power) are
> proportion
no standard way to do cfm of fans.
Thus, the reason why they allow similar fans
within a mfr but not from another mfr. in
some cases.
So, I'm wondering some of the following:
1. Have any you ever run into something
like this before?
2. If you have, what did you do about it?
On and o
n make the microprocessor an interlock device and, as
such, you'd have to go through every single state of the
microprocessor
for single fault analysis?
- Doug McKean
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Maybe sort of off topic.
What's the disposal procedures for batteries such as
the A, AA, AAA, C, D, lithiums ... ?
Are you supposed to just throw them into the trash?
What if a customer a customer calls in to ask such
a question and let's say they're in the US, Canada,
or Europe? What
iations of the intended country of sale,
generate a TCF, then send it off without further
testing to another country?
Or, will there be further testing required?
- Doug McKean
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I don't mean to speak for John, but I think he means
The *scope of a directive* is to indicate WHAT to test.
The *scope of a standard* is to indicate HOW to test.
- Doug
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by a factor of roughly 10.
That makes your product particularly susceptible during emissions.
Anywho, I'll get you the name of the book and specifics for ya.
And if you want, maybe you can pop over here to do some testing.
- Doug McKean
To unsubscribe from si-list or si-list-
liberty to say which company it was but I'm
willing to bet it wasn't the only one.
- Doug McKean
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Joe,
I can think of one I've worked with - dual ac
input mains. It was a redundant powered device.
And redundancy was maintained back to the mains
connection. 2 power supplies, 1 mains per supply.
Both mains inputs were identical branch circuits.
It required redundant primary ground wires.
- D
Thanks to those who answered off-line.
Appreciated the inputs.
- Doug McKean
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Would anyone happen to have the NEC section and
paragraph numbers for power cords under raised
floors handy?
Regards, Doug McKean
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the regular variation of the public
mains. The grid must vary and I don't have any information how
much it varies during the course of, what, a week, month, year?
If the line was reduced to 108vac, what would be the anticipated
low line during normal operation?
- Doug McKean
--
;s a lot
of power cables we're talking about.
Just my two cents.
- Doug McKean
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as asking my question.
If an 'international' version of a power supply
has trouble with a reversed input, then there'd
definitely be a problem in Germany.
- Doug McKean
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haracter
> part number. These little things do sometimes catch designers by
surprise.
I'm not quite sure I understand. The US version had to be used to
pass
immunity testing when the international version couldn't pass
immunity?
- Doug McKean
-
ues at
hand. But, they are outside my point and do not contradict
what I originally said. If however these issues are surprises
in the course of someone's job, then of course there's
reason for concern.
Regards, Doug McKean
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nput, then you've got a single
phase system.
It's effectively what the primary 'sees', one phase and that's what's
counts, AFAIC.
Regards, Doug McKean
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I've worked on products which used triple phase
inputs for different sections of the product and
the main power ON/OFF breakers were usually barred
together as one gang switch. I also had off from
one of those phases a motor which had it's own
ON/OFF switch. And all the switches were marked
r "maintenance"
modes of operation required all the cables to be
connected containing any and all emissions from
the lasers within the cables making the entire
product device Class I which flew with the FDA.
Regards, Doug McKean
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any other factors
to the point of being ignored.
All the above of course, IMHO.
And opinions may vary at any speed.
Regards, Doug McKean
> -Original Message-
> From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf
> Of Ken Javor
> Sent: Friday, April 20, 2001
able to correct hardware design in a blink.
13. Have enough brass to call a "stop ship" at any time.
13. And then once hired, expect to be generally ignored ...
14. Must be willing to work lots of overtime without
being asked.
15. Pay approx $35K max ...
Regards, D
incident occur with intervention from the end user?
Was the end user performing - normal operating procedures,
routine maintenance, an emergency shut down ...
Regards, Doug McKean
- Original Message -
From:
To:
Sent: Thursday, April 19, 2001 7:19 AM
Subject: Safety Incidents
>
dless of the 30vdc?
> The only electronics inside is a bridge
> rectifier and a RC circuit to blink a LED.
Couldn't someone be a total speedbump with
the LED having to be declared to 60825?
- Doug McKean
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- Doug
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t's the same
standard which requires the same testing.
It gets messier when you're talking OEM.
< shudder >
< flashbacks >
Regards, Doug McKean
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device is on an extendable
arm like an antenna. Highly accurate and
very illumenating.
- Doug McKean
ance can mean inductance.
Since, v(t) = L di/dt and with L in nano-henries (10^-9)
and suppose dt in pico-seconds (10^-12), we're already
up in the 10^3 range ... - Doug McKean
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;re correct.
- IF your product is some stand alone system, then
you'll have to go for "Listing".
Regards, Doug McKean
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To cancel your
for the
testing and approval was in Mexico City.
Little dated on this info.
Verify with 2nd source.
Regards, Doug McKean
"Lubeski, Paul" wrote:
>
> Dear List members:
>
> Can anyone provide the Product Safety and Industry/Regulatory Network
> requirements and a
Well, then it's resolved as far as I'm concerned.
If anyone ever asks me to locate the "law" that
requires "approved" equipment in a workplace,
I'm going to point them to
"29 CFR 1910.302(a)(1) - Covered. The provisions
of 1910.302 through 1910.308 of this subpart cover
electrical install
similar useful purpose."
Therefore, people, I submit that since 29 CFR 1910 directs
it's attention to "systems", it is strictly concerned with
that which provides electrical power or lighting and does
NOT concern itself with "equipment", i.e. that utiliize
Peter,
Here's my two cents ...
Extraneous/non-electrical Conductive Part -
1 A conductive part that is not intended
to be part of ANY electrical circuit
(power or otherwise) of a device.
2. If removed from the device, does not
cause any degradation of electrical performa
On Mon, 15 Mar 1999, Lou Gnecco wrote:
> Do you get the same effect with the coins in a cloth bag or a paper bag?
> Has anybody tried it?
> Lou
I can produce almost the same levels by
jingling the same coins in my pocket.
Side Note: Sorta glad my wife and I have our two boys.
-
Th
Telco equip is capable of this problem
in many instances. Once at a former
company, we had two power outlets each
from a different substation in the lab.
We didn't realize that a float of more
than 15VAC existed between them until
we setup a system and actually saw the
coax between them me
The term "island" means "seperate from". There are
certainly some cases where this is necessary. As a
general rule, no one rule, IMO, can be stated for
all cases.
Isolating I/O ground from processor ground may not
mean the complete disconnection of the two. IOW, it
doesn't have to be done wi
Ok, this is rather old but the atmosphere is still
pretty much the same. Assuming your standing at
sea level with 1 atmosphere pressure and +15C temp
and you start to rise in altitude, you'll have
roughly dependent upon alot of other factors ...
AltitudeTemperature Pressure App
Thanks Ed. The friction between a metal surface and air
is indeed very real. The triboelectric series if broken
into thirds would have air at the top for most positive
in the series and metals would be 2/3 of the way down
from the top for most negativity.
Hovering helicopters dropping lines m
Yes Eric,
I have worked with conductive coatings on plastic with
no problems as long as some things are kept in mind -
There's a whole UL thing to it that I can list
if enough people want me to.
The coatings cannot withstand repeated removal
from the product. The coatings are very fragile
Hate to be another ditto but I'm also seeing
this effect with emc-pstc and some other
listservers with which I'm subscribed.
Hi Jon,
I'll take the plunge and give you some of
my answers below ...
> From: Jon Bertrand
>
> Hello Everyone,
>
> A lot of "budding midnight designers" ask these questions on the
> microcontroller newsgroups so I thought I'd ask them here - and
learn
> some
Does someone know of any standard test criteria
or declaration of compliance format for Y2K
compliance instead of "yea, we are"?
Two areas of compliance that I've uncovered are
(1) Time calcs across the year 2000. Calculate
from Dec 31, 1999 to Jan 1, 2000 and one
SHOULD get about 1
FWIW ...
About 10 years ago, I hired a lawyer who specialized
in product liability for a 2 day seminar for engineers
and marketing types.
After alot of nit-picking, it was concluded that RED
lamps or indicators weren't to be used for things
that had anything to do with power. At the bottom
Hi Jeff,
I have worked with single point grounds and I agree with what
you say about single point grounds conditionally. If single point
ground is implemented properly (as with alot of other techniques),
it's fine. The problems I have seen resulting from single point
grounding involve impleme
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