The entire discussion is a Red Herring!
- Doug McKean
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in a working
setup can sometimes telll you what's going on in
a setup that's modelled after a dipole.
Good luck ...
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...
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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.
The power supply will have different criteria with Pass
in 4-4 than your product.
- Doug McKean
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/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.
Equating the two is invalid since you're trying to equate
two different concepts. Doesn't mean anything.
- Doug McKean
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
- 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
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
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. 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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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.
- Doug McKean
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 plaw...@west.net
To: EMC-PSTC emc-p...@ieee.org
Sent: Wednesday, September 19,
of the 84 version
and I don't have any reference to it.
- Doug McKean
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of one or a six-pack of another ...
- Doug McKean
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serious thought.
just my opinion ...
- Doug McKean
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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 McKean
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a
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
NRTL test engineer.
- Doug McKean
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. 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
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 details specific to safety.
Regards, Doug McKean
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 ambient.
- Doug McKean
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
---
This
.
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 McKean
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 something
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 McKean
fields which would
respond in various shades of blue.
- Doug McKean
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problems ...
- Doug McKean
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majord
in the distant past?
- Doug McKean
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majord
. 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 ...)
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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
?
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 products entirely. Battery-operated hand-helds
, 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 of
grounding by safety.
- Doug McKean
in the style of a self
recovering type criteria than anything else.
- Doug McKean
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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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know what you're talking about or doesn't care.
Unneeded testing drives up the baseline production cost per
product. In some instances, this may give one a distinct marketing
disadvantage. Besides, if the testing isn't necessary, I doubt the
residents of mahogany row would approve it.
- Doug
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
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of a product (and thus ALL versions
of the product) is done and finished.
- Doug McKean
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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.
- Doug McKean
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 deviations
(that's minus two) from the mean IQ of the population.
- Doug McKean
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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Just my 3.1415 cents worth ...
- Doug McKean
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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 ste...@transition.com
To: 'IEEE Forum' emc-p...@majordomo.ieee.org
Sent: Wednesday, June 20, 2001 2:03 PM
Subject: RE: FCC + FCC = FCC?
If
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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be such and such in *any* type of PC construction.
- Doug McKean
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is not enough.
2. Control the fan by electrical ratings and physical
size. The electrical ratings (power) are
proportional to cfm.
Good point, but again, it's the cfm as a baseline.
Thanks for your input ...
Regards, Doug McKean
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This message
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 off line responses both welcome ...
Regards, Doug
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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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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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-digest: send e-mail to
majord...@silab.eng.sun.com
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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company it was but I'm
willing to bet it wasn't the only one.
- Doug McKean
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Thanks to those who answered off-line.
Appreciated the inputs.
- Doug McKean
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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
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we're talking about.
Just my two cents.
- Doug McKean
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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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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
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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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, 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
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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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 2:40 PM
To: emc-p...@ieee.org
. Be 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, Doug McKean
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: wo...@sensormatic.com
To: emc-p...@majordomo.ieee.org
Sent: Thursday, April 19, 2001 7:19 AM
?
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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http://www.mcw.edu/gcrc/cop.html
- Doug
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.
It gets messier when you're talking OEM.
shudder
flashbacks
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is on an extendable
arm like an antenna. Highly accurate and
very illumenating.
- Doug McKean
)
and suppose dt in pico-seconds (10^-12), we're already
up in the 10^3 range ... - Doug McKean
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For help, send mail
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 approval authority contact(s
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
, it is strictly concerned with
that which provides electrical power or lighting and does
NOT concern itself with equipment, i.e. that utiliizes
said power.
Comments?
Regards, Doug McKean
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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
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 with
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
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
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
Hate to be another ditto but I'm also seeing
this effect with emc-pstc and some other
listservers with which I'm subscribed.
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
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
A quick search on the web produced these websites:
http://www.ora.com/reference/dictionary/terms/M/MPR_II.htm
http://www.ora.com/reference/dictionary/terms/S/Swedish_Confederation_of_Pro
fessional_Employees.htm
Basically, it's a Swedish standard for limiting emissions
from VDTs or video
From: Metse me...@aol.com
Your assistance if greatly appreciated (even if you can only answer some
of
the questions):
I have a general question concerning the applicable Directive for
equipment
originally classified as ITE here in the US (by an International Lab with
NRTL
accreditation).
Situation: Piece of equipment measures over
3.5 milli-amps for earth leakage test:
According to EN-60950
5.2.5: Equipment with an earth leakage current
exceeding 3,5 mA
CLASS I STATIONARY that is PERMANENTLY CONNECTED
EQUIPMENT,
I've seen switchers cause noise envelopes and
picket fences well into the MHz range. The switching
freq is what (?) 100 kHz, 150 kHz ...
But, for some reason a pulse with a 20 nano-second period
makes me think that maybe a digital signal such as a square
wave is getting differentiated by
From: Arlen Olive arl...@futuretel.com
I've been working on a multimedia board in a standalone box
that connects to a PC parallel port. It also has an external
DC power supply, and connections for audio and video
input and output.
To pass FCC class B, I had to:
1. Shield the box
I'm having a lively discussion with one of our
design engineers about backplane PCB design.
Here's the case:
1. Multilayer board, let's say 10 layers,
1 power plane (+5vdc), 3 ground planes,
6 signal planes.
2. Outside world connections to the
backplane with several connectors
Well, I've been reading the responses, and all I can
say is if you are dealing with a product that will
absolutely draw a constant rate of power for all time,
then you should see no variation *from the product*
unless of course you're in some varying unreliable
environment, or the product
Hi Glenn,
Appreciate your response. but, I believe
you raised two separate and equally valid
points.
1. Insulation breakdown.
2. Some other safety hazard caused by heat.
Understand your primary concern well.
As far as the secondary point, the two of them
fought it out and one had
Is that what you're really seeing -
a harmonic of the clock?
I developed a spreadsheet whereby I can calculate
all sorts of freqs from a product that has been
accurate enough to scare me.
If you want, supply the freqs of all clocks,
incoming/outgoing signals, and any division
being
Hi Kevin,
I had a rather bad experience between UL and CSA in
the older days when there wasn't so much discussion
and agreement between them. I had set up an MOU
between them with UL as the test location.
Went like this ...
Switching power supply. Has a transformer.
Must do abnormals
Recently somewhere back in the news (couple of weeks ago),
two children died when one of them used a hairdryer in
the tub. A discussion this accident with some lead me
to a counter-intuitive result from my experience in
product safety.
**
From: Cortland Richmond 72146@compuserve.com
To: Grasso, Charles (Chaz) gra...@louisville.stortek.com; ieee pstc
list emc-p...@ieee.org
Subject: RE: Antenna Calibration/Site Attenuation
Date: Monday, August 25, 1997 11:19 AM
If it's mutual coupling... sure. But if it's a surface wave,
Hi Eric,
Having been through this a while ago, I'll discuss what
I went through from memory. This information is now 2 years old.
The conductive coating is not a reliable ground. Primary ground
in the product on which I worked was on the switcher. Assembly
line testing hipotted with the
From: Bill Lawrence wlawr...@capecod.net
And in the unusual posting department
Can anyone offer any guidance on who may have jurisdiction over
electrical
equipment installed / used in a sewer?
I hope with all the deregulation in the air,
we aren't suggesting sanitation engineers
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