AC Plug Pack (wall wart) plugs - suggestions please...

[Tabby]

On Thursday, 3 September 2020 23:36:40 UTC+1, Phil Hobbs wrote:

On 2020-09-02 05:44, Tabby wrote:
On Wednesday, 2 September 2020 03:01:50 UTC+1, david eather wrote:

I have in mind a project that will use AC Plug Packs. For safety and
legal reasons I can\'t change that, but I am troubled by the low voltage
power plugs supplied. They are 2.1mm round plugs just like those on
almost any DC plug Pack.

Time marches on plug packs get mixed in together and \"hey this fits\" and
pzzzt... magic smoke happens to someones piece of kit.

are there suggestions for an alternative plug to use. Doesn\'t need to be
polarized (of course), but something hot plug-able would be nice.

Any suggestions?

One simple solution is run the kit at the highest commonish wart voltage, 30 or 32v. And always make your warts output ac so psu polarity doesn\'t matter. Another is to add overvoltage protection. Another is to have the dc socket insde the appliance case. Another is to put the whole wart inside the appliance with just a mains connector user accessible. etc etc.

I gather you\'re retired.

AFAICT the use of AC warts mostly went out with the 56kbaud modem, and
for good reason. That approach requires gigundo wet Al filter caps and
so on in order to be able to handle 50-60 Hz AC. What a waste.

Cheers

Phil Hobbs

I prefer wartable goods to run on anything - they won\'t, but getting partway there is a real plus. If you design for ac in it can run off correct PSUs, wrong polarity & old iron lumps. That was really the motivation behind said approach.

Cap failure doesn\'t matter if it runs on a dc wart, lytics normally go high ESR low C.


NT

 

[Phil Hobbs]

On 2020-09-03 20:29, John Larkin wrote:

On Thu, 3 Sep 2020 18:30:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-09-02 17:44, david eather wrote:
On 2/09/2020 12:35 pm, Phil Allison wrote:
david eather wrote:

==================
I have in mind a project that will use AC Plug Packs. For safety and
legal reasons I can\'t change that, but I am troubled by the low voltage
power plugs supplied. They are 2.1mm round plugs just like those on
almost any DC plug Pack.

Time marches on plug packs get mixed in together and \"hey this fits\" and
pzzzt... magic smoke happens to someones piece of kit.


** Though possible this rarely happens.

Sadly, I confess I have done it. An LED clock that used 5volts got it\'s
own wake up call when I plugged 12 volts into it.  I really needed the
clock and I liked it too.

That\'s why we standardized on +24V. AC won\'t kill our boxes because of
the unidirectional TVS, series Schottky rectifier, and polyfuse.
However, as you go lower in voltage, your box will draw more operating
current, so it\'ll require that much more fault current to switch the
polyfuse if somebody plugs in the wrong wart.

  You need to clearly label your AC pack with the name of the item it
goes with and a warning that it be used with no other.

Yep, I was thinking that would be the best I could do.

Thanks


Try to make the item damage proof if used with a DC pak up to 12V.

24V at least.


We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

As the wise man said, \"Unbreakable toys are very useful for breaking
other toys.\" ;\"

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 2020-09-03 21:43, Tabby wrote:

On Thursday, 3 September 2020 23:36:40 UTC+1, Phil Hobbs wrote:
On 2020-09-02 05:44, Tabby wrote:
On Wednesday, 2 September 2020 03:01:50 UTC+1, david eather
wrote:

I have in mind a project that will use AC Plug Packs. For
safety and legal reasons I can\'t change that, but I am troubled
by the low voltage power plugs supplied. They are 2.1mm round
plugs just like those on almost any DC plug Pack.

Time marches on plug packs get mixed in together and \"hey this
fits\" and pzzzt... magic smoke happens to someones piece of
kit.

are there suggestions for an alternative plug to use. Doesn\'t
need to be polarized (of course), but something hot plug-able
would be nice.

Any suggestions?

One simple solution is run the kit at the highest commonish wart
voltage, 30 or 32v. And always make your warts output ac so psu
polarity doesn\'t matter. Another is to add overvoltage
protection. Another is to have the dc socket insde the appliance
case. Another is to put the whole wart inside the appliance with
just a mains connector user accessible. etc etc.

I gather you\'re retired.

AFAICT the use of AC warts mostly went out with the 56kbaud modem,
and for good reason. That approach requires gigundo wet Al filter
caps and so on in order to be able to handle 50-60 Hz AC. What a
waste.

Cheers

Phil Hobbs

I prefer wartable goods to run on anything - they won\'t, but getting
partway there is a real plus. If you design for ac in it can run off
correct PSUs, wrong polarity & old iron lumps. That was really the
motivation behind said approach.

Cap failure doesn\'t matter if it runs on a dc wart, lytics normally
go high ESR low C.


NT

As I said, I gather you\'re retired.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Don Y]

On 9/3/2020 5:29 PM, John Larkin wrote:

We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

 

[david eather]

On 4/09/2020 8:36 am, Phil Hobbs wrote:

On 2020-09-02 05:44, Tabby wrote:
On Wednesday, 2 September 2020 03:01:50 UTC+1, david eather  wrote:

I have in mind a project that will use AC Plug Packs. For safety and
legal reasons I can\'t change that, but I am troubled by the low voltage
power plugs supplied. They are 2.1mm round plugs just like those on
almost any DC plug Pack.

Time marches on plug packs get mixed in together and \"hey this fits\" and
pzzzt... magic smoke happens to someones piece of kit.

are there suggestions for an alternative plug to use. Doesn\'t need to be
polarized (of course), but something hot plug-able would be nice.

Any suggestions?

One simple solution is run the kit at the highest commonish wart
voltage, 30 or 32v. And always make your warts output ac so psu
polarity doesn\'t matter. Another is to add overvoltage protection.
Another is to have the dc socket insde the appliance case. Another is
to put the whole wart inside the appliance with just a mains connector
user accessible. etc etc.

I gather you\'re retired.

AFAICT the use of AC warts mostly went out with the 56kbaud modem, and
for good reason.  That approach requires gigundo wet Al filter caps and
so on in order to be able to handle 50-60 Hz AC.  What a waste.

Cheers

Phil Hobbs

I\'m retired. An AC plug pack is an usable way for someone to build a bit
of basic power kit without the need to worry about electrical code
compliance with all of those hideous, sometimes hidden and often
changing requirements. In dinosaur days it was possible to do a *fully*
approved (industry, academic and government approved) tertiary diploma
that legally entitled you to fit a plug onto a power cord or work on an
unplugged electrical appliance, but you could not legally do so because
the controlling bodies would not issue you the required ticket unless
you did a full electricians apprenticeship.

You were fully qualified to teach the apprentices how to do it at a
Technical collage, but if you ever tried to do it yourself.....

Such is the stupidity (and closed shop system) that existed in my state
at the time. I have no idea what it is now, but at the time it was so
stupid, so restrictive and so impossible to work with that just about
everyone who could ignored it. No longer an option today when you can be
sued for just about anything.

Low voltage AC is more friendly to simple construction methods - perf
board, strip board, hideous home made PCBs brawn by hand. etc. Easier to
find components in small quantities, easier to trouble shoot and debug
etc. And no switching noise to unexpectedly stick it\'s nose in where it
is not wanted.

 

[Don Y]

On 9/4/2020 2:47 AM, david eather wrote:

I\'m retired. An AC plug pack is an usable way for someone to build a bit of
basic power kit without the need to worry about electrical code compliance with
all of those hideous, sometimes hidden and often changing requirements. In

Wall warts, bricks, etc. are a cheap way for manufacturers (here) to \"inherit\"
the agency approvals (from the wall wart vendors) instead of doing their own
testing and certification.

Such is the stupidity (and closed shop system) that existed in my state at the
time. I have no idea what it is now, but at the time it was so stupid, so
restrictive and so impossible to work with that just about everyone who could
ignored it. No longer an option today when you can be sued for just about
anything.

Low voltage AC is more friendly to simple construction methods - perf board,
strip board, hideous home made PCBs brawn by hand. etc. Easier to find
components in small quantities, easier to trouble shoot and debug etc. And no
switching noise to unexpectedly stick it\'s nose in where it is not wanted.

If you\'re looking for \"hobbyist quantities\" and not pressed for cost/price,
there are many options that you can pursue.

For example, electric wheelchairs/scooters/mobility aids use XLR connectors
to handle the increased current capacity (it\'s not uncommon for a charger to
deliver 8-10A) as well as making the mating of the connector a bit easier
(mechanically keyed, large, visible, etc. so folks living with one -- or
more! -- handicap aren\'t also penalized trying to mate some silly connector
that comes in umpteen different combinations of ID & OD & polarity & voltage
& ampacity.

There are many miniDIN connectors (often flimsy) as well as other heftier
circular connectors (some with mechanical fasteners to ensure they stay mated).

You can also find molded connectors -- OTS and custom -- that can suit your
needs... once you\'ve specified them! :>

[I really like connectors that can be mated \"blind\"... but that sorely
limits your selections]

 

[Joe Gwinn]

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid>
wrote:

On 9/3/2020 5:29 PM, John Larkin wrote:
We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

The Power over Ethernet voltage is 48 Vdc for this reason. The
connector pins et al are limited to two amps, so the highest available
voltage was used.

Joe Gwinn

 

[Don Y]

On 9/4/2020 10:22 AM, Joe Gwinn wrote:

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

I\'m not sure how much \"wall-wart powered\" kit like that exists (?)

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

You still have to follow the NEC when routing low voltage signals;
esp network cabling.

The Power over Ethernet voltage is 48 Vdc for this reason. The
connector pins et al are limited to two amps, so the highest available
voltage was used.

I think heating in the conductors is the bigger concern (not ampacity of
connector). Note that legacy PoE only draws ~350mA.

By contrast, a bundle of LONG cables (possibly in a raceway) can
dissipate a fair bit of heat in that enclosed volume. (you also risk
significant voltage drop \"at load\" at the PD)

PoE+ just makes things worse. And 4PPoE is just insane!! :-/
(Sheesh! Why not power your *TV* over the network? Or, charge your
electric vehicle?? :> )

 

[Chris]

On 09/04/20 01:29, John Larkin wrote:

On Thu, 3 Sep 2020 18:30:06 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-09-02 17:44, david eather wrote:
On 2/09/2020 12:35 pm, Phil Allison wrote:
david eather wrote:

==================
I have in mind a project that will use AC Plug Packs. For safety and
legal reasons I can\'t change that, but I am troubled by the low voltage
power plugs supplied. They are 2.1mm round plugs just like those on
almost any DC plug Pack.

Time marches on plug packs get mixed in together and \"hey this fits\" and
pzzzt... magic smoke happens to someones piece of kit.


** Though possible this rarely happens.

Sadly, I confess I have done it. An LED clock that used 5volts got it\'s
own wake up call when I plugged 12 volts into it. I really needed the
clock and I liked it too.

That\'s why we standardized on +24V. AC won\'t kill our boxes because of
the unidirectional TVS, series Schottky rectifier, and polyfuse.
However, as you go lower in voltage, your box will draw more operating
current, so it\'ll require that much more fault current to switch the
polyfuse if somebody plugs in the wrong wart.

You need to clearly label your AC pack with the name of the item it
goes with and a warning that it be used with no other.

Yep, I was thinking that would be the best I could do.

Thanks


Try to make the item damage proof if used with a DC pak up to 12V.

24V at least.

Cheers

Phil Hobbs

We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Should be cheap, safe and multisource as well, since power over
over ethernet uses a 48 volt rail...

Chris

 

[John Larkin]

On Thu, 3 Sep 2020 18:43:48 -0700 (PDT), Tabby <tabbypurr@gmail.com>
wrote:

On Thursday, 3 September 2020 23:36:40 UTC+1, Phil Hobbs wrote:
On 2020-09-02 05:44, Tabby wrote:
On Wednesday, 2 September 2020 03:01:50 UTC+1, david eather wrote:

I have in mind a project that will use AC Plug Packs. For safety and
legal reasons I can\'t change that, but I am troubled by the low voltage
power plugs supplied. They are 2.1mm round plugs just like those on
almost any DC plug Pack.

Time marches on plug packs get mixed in together and \"hey this fits\" and
pzzzt... magic smoke happens to someones piece of kit.

are there suggestions for an alternative plug to use. Doesn\'t need to be
polarized (of course), but something hot plug-able would be nice.

Any suggestions?

One simple solution is run the kit at the highest commonish wart voltage, 30 or 32v. And always make your warts output ac so psu polarity doesn\'t matter. Another is to add overvoltage protection. Another is to have the dc socket insde the appliance case. Another is to put the whole wart inside the appliance with just a mains connector user accessible. etc etc.

I gather you\'re retired.

AFAICT the use of AC warts mostly went out with the 56kbaud modem, and
for good reason. That approach requires gigundo wet Al filter caps and
so on in order to be able to handle 50-60 Hz AC. What a waste.

Cheers

Phil Hobbs

I prefer wartable goods to run on anything - they won\'t, but getting partway there is a real plus. If you design for ac in it can run off correct PSUs, wrong polarity & old iron lumps. That was really the motivation behind said approach.

A transformer has the 120/240 problem. We buy universal-input DC-out
warts with the full international plug set. There are some really
weird ones.

Cap failure doesn\'t matter if it runs on a dc wart, lytics normally go high ESR low C.


NT

Just put one of these first-thing:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=srh05

 

[whit3rd]

On Friday, September 4, 2020 at 11:47:23 AM UTC-7, Don Y wrote:

On 9/4/2020 10:22 AM, Joe Gwinn wrote:
On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

I\'m not sure how much \"wall-wart powered\" kit like that exists (?)

There\'s a fair amount of switches that are intended to power small items
(cameras, WiFi hotspots, IOT debris) and those generally use, not a wall tumor,
but a boa-digesting-a-sheep style 48V brick.

Ideally, this is -48V (the case ground is positive)
One lineup:
<https://www.netgear.com/business/products/switches/>

 

[Don Y]

On 9/4/2020 12:05 PM, whit3rd wrote:

On Friday, September 4, 2020 at 11:47:23 AM UTC-7, Don Y wrote:
On 9/4/2020 10:22 AM, Joe Gwinn wrote:
On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

I\'m not sure how much \"wall-wart powered\" kit like that exists (?)

There\'s a fair amount of switches that are intended to power small items
(cameras, WiFi hotspots, IOT debris) and those generally use, not a wall tumor,
but a boa-digesting-a-sheep style 48V brick.

Most switches seem designed to power phones -- ~7W PDs. And, often
not a PD per port (but some subset of that). Often an external power
supply can augment the power available to the PSE. But, these are
usually via \"nonstandardized\" connectors (certainly not a barrel connector)

E.g., a 48 port PSE would need ~700W of PSE capacity just for \"nominal\" PDs.
(half that if just dealing with phones; half of THAT if only supporting a
subset of phone ports!)

I\'ve not seen an external power supply larger than a single PSE\'s
capacity, though (all of my APs can be configured for midspan injectors
or *direct* connection of the wall wart to the AP -- a barrel connector
in each case). IME (YMMV), any supply that would handle multiple PDs
was integrated into the switch and powered from the mains.

My (~2KW) switch\'s design is powered from 48VDC -- but, as a hack!
This lets me use the battery in my UPS directly to power the switch
(instead of converting to 120VAC and then back to 48VDC) as well as
sourcing power from a 48V solar panel.

Not \"listed\" kit, though! :>

Ideally, this is -48V (the case ground is positive)
One lineup:
https://www.netgear.com/business/products/switches/

 

[Tabby]

On Friday, 4 September 2020 19:59:55 UTC+1, John Larkin wrote:

On Thu, 3 Sep 2020 18:43:48 -0700 (PDT), Tabby <tabbypurr> wrote:
On Thursday, 3 September 2020 23:36:40 UTC+1, Phil Hobbs wrote:
On 2020-09-02 05:44, Tabby wrote:
On Wednesday, 2 September 2020 03:01:50 UTC+1, david eather wrote:

I have in mind a project that will use AC Plug Packs. For safety and
legal reasons I can\'t change that, but I am troubled by the low voltage
power plugs supplied. They are 2.1mm round plugs just like those on
almost any DC plug Pack.

Time marches on plug packs get mixed in together and \"hey this fits\" and
pzzzt... magic smoke happens to someones piece of kit.

are there suggestions for an alternative plug to use. Doesn\'t need to be
polarized (of course), but something hot plug-able would be nice.

Any suggestions?

One simple solution is run the kit at the highest commonish wart voltage, 30 or 32v. And always make your warts output ac so psu polarity doesn\'t matter. Another is to add overvoltage protection. Another is to have the dc socket insde the appliance case. Another is to put the whole wart inside the appliance with just a mains connector user accessible. etc etc.

I gather you\'re retired.

AFAICT the use of AC warts mostly went out with the 56kbaud modem, and
for good reason. That approach requires gigundo wet Al filter caps and
so on in order to be able to handle 50-60 Hz AC. What a waste.

Cheers

Phil Hobbs

I prefer wartable goods to run on anything - they won\'t, but getting partway there is a real plus. If you design for ac in it can run off correct PSUs, wrong polarity & old iron lumps. That was really the motivation behind said approach.

A transformer has the 120/240 problem. We buy universal-input DC-out
warts with the full international plug set. There are some really
weird ones.

If you mean old iron lump ones, I think there were occasional ones that autoswitched.

Cap failure doesn\'t matter if it runs on a dc wart, lytics normally go high ESR low C.


NT

Just put one of these first-thing:

https://www.digikey.com/products/en/power-supplies-board-mount/dc-dc-converters/922?k=srh05

a nice option if budget is generous. Appreciated by some users.


NT

 

[david eather]

On 5/09/2020 3:22 am, Joe Gwinn wrote:

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

On 9/3/2020 5:29 PM, John Larkin wrote:
We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

in OZ it was (is?) 32 VAC, 110 VDC

 

[Michael_A_Terrell]

Tabby wrote:

On Thursday, 3 September 2020 14:39:07 UTC+1, Michael_A_Terrell wrote:
Clive Arthur wrote:

Use two connectors, one for each pole.


Is that a Polish joke?

one shared between 2 poles.

I knew one Polish EE. He worked for Square D, and he told the worst
jokes. Mostly about the \'Polish Mafia\'. \"You do whata I say, or I shoot
my family!\" is not funny. Neither was the one about burning his lips
trying to blow up a city bus.


--
Never piss off an Engineer!

They don\'t get mad.

They don\'t get even.

They go for over unity! ;-)

 

[server]

On Fri, 04 Sep 2020 13:22:34 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

On 9/3/2020 5:29 PM, John Larkin wrote:
We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

In most standards (including IEC) the dividing line between ELV (Extra
Low Voltage) and LV is 50 Vac. For DC, the limits varies more, most
standards use 60 Vdc, some 75 V and some 120 V (+/-60 V).

The DC limit must include peak ripple voltage. A 60 V battery voltage
should not be used, since the charging voltage would be over 60 V. For
this reason, typically 48 V (nominal) is the highest battery voltage
used.

 

[server]

On Saturday, 5 September 2020 07:50:00 UTC+1, upsid...@downunder.com wrote:

On Fri, 04 Sep 2020 13:22:34 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

On 9/3/2020 5:29 PM, John Larkin wrote:
We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

In most standards (including IEC) the dividing line between ELV (Extra
Low Voltage) and LV is 50 Vac. For DC, the limits varies more, most
standards use 60 Vdc, some 75 V and some 120 V (+/-60 V).

The DC limit must include peak ripple voltage. A 60 V battery voltage
should not be used, since the charging voltage would be over 60 V. For
this reason, typically 48 V (nominal) is the highest battery voltage
used.

Some of the Netgear POE+ switches use a dc power supply rated at 54V.

John

 

[Phil Hobbs]

On 2020-09-05 02:49, upsidedown@downunder.com wrote:

On Fri, 04 Sep 2020 13:22:34 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

On 9/3/2020 5:29 PM, John Larkin wrote:
We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

In most standards (including IEC) the dividing line between ELV (Extra
Low Voltage) and LV is 50 Vac. For DC, the limits varies more, most
standards use 60 Vdc, some 75 V and some 120 V (+/-60 V).

The DC limit must include peak ripple voltage. A 60 V battery voltage
should not be used, since the charging voltage would be over 60 V. For
this reason, typically 48 V (nominal) is the highest battery voltage
used.

The standards have all changed, so that they focus on the available
energy. The SELV exemption has gone away and been replaced by something
much more complicated.

(I looked into it a little bit a couple of years ago but didn\'t need to
become acquainted with most of the details.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[server]

On Sun, 6 Sep 2020 14:39:18 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-09-05 02:49, upsidedown@downunder.com wrote:
On Fri, 04 Sep 2020 13:22:34 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

On 9/3/2020 5:29 PM, John Larkin wrote:
We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

In most standards (including IEC) the dividing line between ELV (Extra
Low Voltage) and LV is 50 Vac. For DC, the limits varies more, most
standards use 60 Vdc, some 75 V and some 120 V (+/-60 V).

The DC limit must include peak ripple voltage. A 60 V battery voltage
should not be used, since the charging voltage would be over 60 V. For
this reason, typically 48 V (nominal) is the highest battery voltage
used.



The standards have all changed, so that they focus on the available
energy. The SELV exemption has gone away and been replaced by something
much more complicated.

It sounds like you are talking about standards for the EX (explosive
atmosphere) devices
https://en.wikipedia.org/wiki/Electrical_equipment_in_hazardous_areas

In these systems it is critical that the voltage, current (and power)
fed into a device within the EX area is kept so low that it can\'t
ignite the gas/dust in the EX area. Barriers outside the EX area are
used to limit the voltage and current and a single failure in the
barrier should not admit too much voltage/current into the device in
the EX area.

(I looked into it a little bit a couple of years ago but didn\'t need to
become acquainted with most of the details.)

Cheers

Phil Hobbs

 

[server]

On Sunday, 6 September 2020 20:40:00 UTC+1, upsid...@downunder.com wrote:

On Sun, 6 Sep 2020 14:39:18 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-09-05 02:49, upsidedown@downunder.com wrote:
On Fri, 04 Sep 2020 13:22:34 -0400, Joe Gwinn <joegwinn@comcast.net
wrote:

On Thu, 3 Sep 2020 20:28:34 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

On 9/3/2020 5:29 PM, John Larkin wrote:
We like 24 because it\'s unlikely that anybody has a higher voltage
wart around, to plug in by mistake.

Of course, my new pulse generator ships with a 48v wart!

Midspan injectors and a fair bit of industrial networking kit (e.g., APs)
are powered from 48VDC. Not likely found in residences -- but not an
assurance for commercial establishments.

Well, 48 Vdc is the traditional Telcom voltage, so there is lost of
stuff available for that voltage.

In the US (and I suspect everywhere), the legal dividing line between
low voltage and lines voltage is around 50 Vdc, so this is the highest
voltage one can use and not have to follow the National Electrical
Code for power line systems. In Japan, this starts at 100 Vac, in the
US it\'s 120 Vac, and everywhere else it\'s ~240 Vac.

In most standards (including IEC) the dividing line between ELV (Extra
Low Voltage) and LV is 50 Vac. For DC, the limits varies more, most
standards use 60 Vdc, some 75 V and some 120 V (+/-60 V).

The DC limit must include peak ripple voltage. A 60 V battery voltage
should not be used, since the charging voltage would be over 60 V. For
this reason, typically 48 V (nominal) is the highest battery voltage
used.



The standards have all changed, so that they focus on the available
energy. The SELV exemption has gone away and been replaced by something
much more complicated.

It sounds like you are talking about standards for the EX (explosive
atmosphere) devices
https://en.wikipedia.org/wiki/Electrical_equipment_in_hazardous_areas

In these systems it is critical that the voltage, current (and power)
fed into a device within the EX area is kept so low that it can\'t
ignite the gas/dust in the EX area. Barriers outside the EX area are
used to limit the voltage and current and a single failure in the
barrier should not admit too much voltage/current into the device in
the EX area.


(I looked into it a little bit a couple of years ago but didn\'t need to
become acquainted with most of the details.)

Cheers

Phil Hobbs

The current safety standard for audio/video, information and
communication technology equipment is IEC 62368.1:1998.
This does categorise energy sources according to how much damage
they can do, whether it be electric shock, ignition and propagation
of fire or mechanical energy such as fan blades.
One of the boundaries for dc is still 60V.
It does seem to be a generally well thought out standard, although
there are a few areas that are ambiguous and subject to interpretation
by the test lab.
This standard becomes mandatory in the EU and UK at the end of 2020 - we
are currently in a transition period where IEC 62368.1 can be used
alongside IEC 60950.1 and IEC 60065.
I think it only becomes mandatory in Australia and New Zealand in
Feb 2022. No doubt other countries will vary.

John