Re: [PSES] Deviations from ANSI C63.4 testing - Lab acceptability

[Ghery S. Pettit]

Given the ready availability of devices with HDMI ports I would not
recommend using an active termination.  I believe that wording was provided
in case the lab is testing a product using a new interface for which
peripheral devices may not be readily available.  I know we made sure to use
live devices when I worked for Intel.

 

Ghery S. Pettit

 

 

From: Grasso, Charles [mailto:charles.gra...@echostar.com] 
Sent: Monday, March 20, 2017 12:24 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Deviations from ANSI C63.4 testing - Lab acceptability

 

ANSI C63.4 requires that "Interconnect cabling or wiring shall be connected
to one of each type of functional port of the EUT,

and each cable or wire shall be terminated in a device typical of actual
usage."   If an active termination (i.e such as for HDMI)
is used in place of a device, could/would/should a test lab agree to issue a
test report IF the deviation from the ANSI spec
is documented in the test report?

 

Best Regards

Charles Grasso

Compliance Engineer

Echostar Communications

(w) 303-706-5467

(c) 303-204-2974

(t)   3032042...@vtext.com

(e)   charles.gra...@echostar.com

(e2)   chasgra...@gmail.com

 

 

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[PSES] SD Card ESD Testing

[Grasso, Charles]

Aside from the obvious air discharge tests around the SD card slot (with and 
without the SD card installed) are there
any concerns regarding the ESD performance of the SD card during INSERTION?

Does anyone have an insight into this?

TIA


Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042...@vtext.com
(e) charles.gra...@echostar.com
(e2) chasgra...@gmail.com




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This message is from the IEEE Product Safety Engineering Society emc-pstc 
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http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

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[PSES] Deviations from ANSI C63.4 testing - Lab acceptability

[Grasso, Charles]

ANSI C63.4 requires that "Interconnect cabling or wiring shall be connected to 
one of each type of functional port of the EUT,
and each cable or wire shall be terminated in a device typical of actual 
usage."   If an active termination (i.e such as for HDMI)
is used in place of a device, could/would/should a test lab agree to issue a 
test report IF the deviation from the ANSI spec
is documented in the test report?

Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042...@vtext.com
(e) charles.gra...@echostar.com
(e2) chasgra...@gmail.com



-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


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http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
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David Heald: 

Re: [PSES] AC/DC power conversion and system architecture (in-rush limiting, reliability, cabling)

[Brian O'Connell]

From: Adam Dixon [mailto:lanterna.viri...@gmail.com]
Sent: Sunday, March 19, 2017 9:59 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] AC/DC power conversion and system architecture (in-rush 
limiting, reliability, cabling)

Long post from this weekend's studies I have been thinking about power 
distribution system tradeoffs for large systems where multiple AC/DC power 
supplies are used.  Surveying 5 or 6 suppliers, picking an arbitrary 100W - 
200W range for comparison, I see in-rush current specs with a very wide range 
(14A to 80A) and a bit of variation in the specified voltages.  Some like to 
specify at 200VAC, others at 230VAC -- all are auto-switching universal input, 
so the datasheet numbers must be scaled to make an equivalent comparison.
The first one or two cycles are mostly to fill up the DC bus caps. Some PFC 
implementations could increase the period of inrush to three to ten cycles. 
That said, the peak for the inrush current is (at least for my employer’s 
stuff) is well under 1mSec for one or two cycles. Auto-switch designs are not 
same as ‘universal’ input. Some auto-switch units will also have another inrush 
condition during transition from 120V to 230V input. In any case, the inrush 
number is useless unless for the least favorable normal operating condition, 
which is typically 230V.
Targeting a 50-70% of full load rating for improved reliability seems 
reasonable from reviewing qualification data, as well as past discussions with 
two suppliers.  That will in some cases increase the number of power supplies 
in the system based on mounting location, ease of manufacture and cabling for a 
large physical structure.  Voltage drop on the DC output is another parameter 
that affects power supply location.

Reduced FL will not necessarily increase MTBF; and for many SMPS designs, 
output load does not necessarily affect the peak inrush current, but can affect 
the period of initial high input current. Input V and source Z are the dominate 
factors for inrush, but for power supplies that have a de-rating for some 
operating conditions, the 50% load can be an interesting test condition.

I'd appreciate feedback about in-rush current limiting hardware at the system 
level.  I've seen power supply specifications with block diagrams that identify 
in-rush limiting circuitry which I expect are mostly either NTC's or planar 
surge resistors. At the system level, it looks like three main options:  a 
hybrid surge resistor/bypass relay module (European suppliers(?)), a softstart 
controller (targets motor applications) and switched outlet PDU's for data 
center applications.  I think the hybrid module is best for a largely 
capacitive inputs and these modules' datasheets give a capacitive load rating 
(1500uF up to 1uF from what I've seen so far).  Network access for the 
smart switched outlet PDU is probably not an option for the system design.
‘System’ level inrush limiters could cause problems for some edge cases. If 
input current rise or voltage rise goes non-monotonic, some SMPS designs will 
not be happy. While NTCs are typical solutions to SMPS inrush limiting, there 
are obvious problems where input power can be cycled after the unit has reached 
operating temperature, and for efficiency. The common solution is a relay 
across the input NTC, so the NTC never stays warm, and less power and less heat.
Have seen a few soft-start functions of control ICs that resulted in weird 
poles and zeros. And some were indeterminate given certain input conditions. So 
depends on the design and how used
Inrush-limited PDUs can be problematic for both EMI problems and safety hazards 
where the inrush limiting solution is not closely mapped to characteristics of 
the particular power conversion equipment.
There also look to be moderate cost differences by technology type/application.
Any good reference material beyond supplier datasheets and application notes?  
I've done some searching this weekend and have seen one general lighting 
reference with estimates for rectifier/PFC topologies of being 30-100x of 
operating current for in-rush, which doesn't mate well with how the circuit 
breakers are spec'd (10x to 30x for the millisecond range in-rush transient).  
I've also seen a few data center-oriented papers and quite a few pages/papers 
for inductive motor in-rush applications which is not what I am considering.

The Pressman book on SMPS design is recommended. Many component power supply 
mfrs have published guides for the end-use equipment designer.

There are special considerations for motor power ≥ ½ HP in both the way things 
are connected per NEC, and for power supply design considerations.

Branch circuits typically use CBs for current interrupt, which are less 
affected by short-interval overloads.

Any suppliers of preference worth evaluating for in-rush limiting for a 12-16A 
operating current application with common AC/DC open/closed frame supplies?
Is the 50-70% FL de-rating for