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Hi Avinom

Yes Avinom that is one of the test that is done, plus other propietary
transients we subject our boxes to.

At 11:45 AM 8/16/00 -0400, Avinom Levy wrote: 

> Roger,
> You mentioned few times  the high voltage on the equipment during tests. I
> want to make sure we are on the same page, are you refer to the ESD standard
> IEC61000-4-2, or other? 
> Avinoam Levy
> PowerDsine
> -----Original Message----- From:   R karam [SMTP:rkaram@xxxxxxxxx] Sent:  
> Mon, August 14, 2000 11:53 AM To:     Yair Darshan Cc:    
> stds-802-3-pwrviamdi@xxxxxxxx Subject:        Cross Talk Hi Yair Please find
> my reply to the issues below. I am glad Yair is looking into this, and more
> of us should, last meeting a lot of data was presented but there is no way I
> can cover the infinite ammount of details and do every measurement and
> examine every angle, also the impression I got was that, it was not the
> expectation either (that I do all the work) !.
> At 12:09 PM 8/13/00 +0200, Yair Darshan wrote: >Hi Roger, >Regarding cross
> talk issue, to my opinion the situation is more complicated >since there is
> more than one port caring power >to the media and it is not clear to me what
> will be the impact of crosstalk >and other noise issues in the following
> cases: > >1.  If a single power supply output is connected to the center tap
> of the >data transformer (Phantom connection) >     and obviously we have more
> than one Data+Power output (12 or 24 etc..) >than we can say that all center
> taps of all >     data transformers are "shorted"  together at high frequency
> signals. >     (Each Receive-Transmitt center tap of the transformer is
> shorted by the >power supply output capacitor. All the Receive >    
> transformer center taps are shorted together and the same applies for >all
> the transmit center taps.)   Point well taken,   Before power came along,
> Center taps sat on AC ground via capacitors   So AC-wise they sat on the same
> reference or were connected together.        Again we are back to the
> implementation issue, if the center taps    are all tied together we still
> have to make sure that no high frequency    exits and possibly enters the
> system, why is it an issue if a capacitor to ground    is added on these
> center taps to make them sit at AC ground?     And there will almost always
> be a choke between the supply and the WIRE (or    the center tap) to insure
> EMI compliance thus high frequency attenuation!!)    again do we want to get
> into the design of the power supply/system at this stage?    unless of course
> I am missing the point?? > >2.  Same as 1, but all outputs has separate power
> supply output. In this >case there is some parasitic capacitance between each
> >     DC output although they are isolated from each other. The Data that I
> collected  proves that high frequency noise on the center tap will cause EMI
> headaches, and a FILTER will be needed of course unless the power supply is
> designed to be Ultra quiet.  Either way, that center tap must not see any
> high frequency noise, and the noise at frequencies below 1MHZ did not seem to
> affect us in anyway, please see the graph at the end of my presentation,
> where the amplitude at different frequencies is quantified. Like Bob Love
> said, 100TX does not have tons of margin, but again the noise current that
> makes us fail EMI is on the order of (micro amps- common mode) and if care is
> taken to pass emi chances are we are in good shape.   > >3.  Add to the above
> description the fact that from EMI reasons there is >about 1 to 10nF between
> power supply output to >     power supply chassis ( = system gnd) thus the
> construction of the >connections may not be balanced. > >Questions raised
> from the above cases are: > >1. What will be the impact on the requirements
> for cross talks between one >port to other ports, >    is there a problem
> here? By inspection I do not see an issue here, I am very sure we will have
> different "2 cents" on this.   Also we have built 48 porters and did not see
> any issues.... >2. Is there any restrictions in the 802.3 standards (or any
> other standard) >for zero voltage isolation between each data path >   to an 
> other port data path? >    (If there is,  We will need isolated power supply
> for each port) Yair, good question again, If I understand your ? right the
> spec is about 2250dc (from memory) to ground or about 1500v ac to gound on
> the port, and 500v between ports.   Some quad magnetic may have affected the
> port-port isolation due to the proximity of the pins (adjacent port pins) and
> the breakdown of the air-gap. > >What is your opinion regarding the above
> issue? > in summary, you ask valid and good questions, I will try to help
> analyze and measure, and I am hoping that the work is shared among   many of
> us present in the group. thank's roger