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Parallel Connecting Two Identical Switching PSUs

L

Lionel

Jan 1, 1970
0
Why don't you plonk the phil thing? Everyone else has.

I think he's long overdue for a Net Kook award, so I'm campaiging on
his behalf. If you don't want to watch the fun (your loss), you might
want to kill any threads that are crossposted to alt.usenet.kooks.
OTOH, you're most welcome to join the fun, because it can be pretty
entertaining, & Philthy is eligble in a number of categories. ;^)

CF:"The Way of the Kook": <http://www.searchlores.org/way_kook.htm>
 
L

Lionel

Jan 1, 1970
0
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From: "Phil Allison" <[email protected]>
Newsgroups: sci.electronics.design
Subject: Simpson = MORON
Date: Mon, 26 Mar 2007 13:04:44 +1000
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"Homer J Simpson"


** YOU are disgusting and pathetic MORON - " Simpson".

Lionel is an obvious crazy person and a blatant TROLL.

Is your reading comprehension so INEPT you cannot tell ?




....... Phil
 
P

Phil Allison

Jan 1, 1970
0
"Lionel" <[email protected]>


** This pile of VILE sub human garbage is yet another psychotic TROLL

As narcissistic and malicious as they come.

Another stinking, usenet CRIMINAL.

**** him off.



......... Phil
 
L

Lionel

Jan 1, 1970
0
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From: "Phil Allison" <[email protected]>
Newsgroups: sci.electronics.design
Subject: Lionel = CRIMINAL LIAR
Date: Mon, 26 Mar 2007 13:08:48 +1000
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"Lionel" <[email protected]>


** This pile of VILE sub human garbage is yet another psychotic TROLL

As narcissistic and malicious as they come.

Another stinking, usenet CRIMINAL.

**** him off.



........ Phil

Aw, what's the matter Phil? Am I bothering you?
 
P

Phil Allison

Jan 1, 1970
0
" Lionel" <[email protected]>


** This pile of VILE sub human garbage is yet another psychotic TROLL

As narcissistic, autistic and malicious as they come.

Another stinking, usenet CRIMINAL.

**** him off.





......... Phil
 
L

Lionel

Jan 1, 1970
0
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From: "Phil Allison" <[email protected]>
Newsgroups: sci.electronics.design
Subject: Lionel = CRIMINAL TROLL
Date: Mon, 26 Mar 2007 13:28:44 +1000
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" Lionel" <[email protected]>


** This pile of VILE sub human garbage is yet another psychotic TROLL

As narcissistic, autistic and malicious as they come.

Another stinking, usenet CRIMINAL.

**** him off.





........ Phil

Yet another identical kook-fart from Philthy.

What's the matter Philthy, got your period?
 
H

Holophote

Jan 1, 1970
0
All the info about paralleling three terminal regulators
is now online.

I just grabbed my copy of National Semiconductor's
Voltage Regulator Handbook. I've got most of their old
publications. There are thousands of examples in all
these publications, going back to the early 1980's.

The question I had was about switching supplies, not
linear supplies built from three terminal regulators.

One of many examples showing two LM338's used to create a 10 amp
supply is on page 10-72 of this old NS data book. It was published in
1982.

Why are you guys using this forum to vent your anger?
Most of the people I've know who are professionals in technical fields
tend to keep a cool head. May I suggest
you all start doing the same.
 
P

Phil Allison

Jan 1, 1970
0
"Holophote"


** Pick on the culprit.

Not the victim.

You pig ignorant asshole.





....... Phil
 
R

Rich Grise

Jan 1, 1970
0
Subject: "Parallel Connecting Two Identical Switching PSUs" - which
can't be done without a strong risk of letting out the magic smoke.


No problem, I'm keen to learn. So, how do you do it without additional
components, & without reducing regulation quality?

You either don't, or you just tie them in parallel and watch them
destroy each other.

Cheers!
Rich
 
A

Art Deco

Jan 1, 1970
0
Lionel said:
Translation from Philthish to English: "Oh shit, he's got me there.
I'd better scream & yell so nobody notices! That ALWAYS works!"


Translation from Philthish to English: "Oh shit, how can I scare him
off?"

Seconded. crasston needs some competition.
 
J

James Beck

Jan 1, 1970
0
All the info about paralleling three terminal regulators
is now online.

I just grabbed my copy of National Semiconductor's
Voltage Regulator Handbook. I've got most of their old
publications. There are thousands of examples in all
these publications, going back to the early 1980's.

The question I had was about switching supplies, not
linear supplies built from three terminal regulators.

One of many examples showing two LM338's used to create a 10 amp
supply is on page 10-72 of this old NS data book. It was published in
1982.

Why are you guys using this forum to vent your anger?
Most of the people I've know who are professionals in technical fields
tend to keep a cool head. May I suggest
you all start doing the same.
I'm guessing you haven't been here long.
I suggest you do a google groups search on "Phil Allison" and all shall
become clear to you.

Jim
 
J

John Barrett

Jan 1, 1970
0
Holophote said:
If electronics has been your hobbly or
profession for many years, I'm sure you've
connected two identical linear regulators.
An example would be connecting two 5 amp
LM338 regulators to produce a 10 amp supply.

I've never done this with identical switchmode
regulators, and I'm wondering if it's practical
or even possible?

I've got two 20 volt - 3 amp brick style (also
called table-top) switching power supplies.
I'd like to combine the ouputs. In effect,
you would end up with an 20 volt - 6 amp
supply.

They are manufactured by Pihong.
Model No. PSA60W-200.

place a low drop out diode on the output of each supply so they dont fight
with each other... the supply with the slighty higher voltage (and there
will be one slightly higher even if its only by milivolts) will supply all
the current until the load draws enough current to pull the voltage down
slightly... at which point the other supply will begin to supply some of the
current.

if the supplies have output voltage adjustment, you can attempt to get them
balanced as closely as possible with a volt meter, but you would probably
have more luck getting a current meter on the output of each supply (between
the supply and the diode mentioned above), then adjust the output voltage
under load until both supplies are providing current...

You will probably want to get stand alone panel meters for that -- they can
be had on ebay cheap enough, and other sources (see the 4 digit panel meters
thread started on 3/26 in this group) and leave them permanently attached
since the settings will likely drift over time and will need to be tweaked
now and again.

simpler by far to buy a higher current power supply !!
 
E

ehsjr

Jan 1, 1970
0
Holophote said:
If electronics has been your hobbly or
profession for many years, I'm sure you've
connected two identical linear regulators.
An example would be connecting two 5 amp
LM338 regulators to produce a 10 amp supply.

I've never done this with identical switchmode
regulators, and I'm wondering if it's practical
or even possible?

I've got two 20 volt - 3 amp brick style (also
called table-top) switching power supplies.
I'd like to combine the ouputs. In effect,
you would end up with an 20 volt - 6 amp
supply.

They are manufactured by Pihong.
Model No. PSA60W-200.

You could Rube Goldberg a ~15 volt output
(or ~18 with an LDO):

-----
+20+------+---->|---+----+---|V Reg|---+--- Vout
| + | | | ----- |
Switcher [R] | [C] | [C]
| | | | | |
+------+---|<--- | ---+------+------+--- Gnd
| |
+20+------+---->|---+ |
| + | |
Switcher [R] |
| | |
+------+---|<---------+

Feasible, perhaps, but more of an experimental idea
than anything else.

Ed
 
M

Meat Plow

Jan 1, 1970
0
Yet another identical kook-fart from Philthy.

What's the matter Philthy, got your period?

Sheeesh! Wonder what meds he's off this time?

--
#1 Offishul Ruiner of Usenet
#1 Bartlo Pset March 13-24 2007
#1 Usenet Asshole
Pierre Salinger Memorial Hook, Line & Sinker, June 2004
COOSN-266-06-25794
 
W

w_tom

Jan 1, 1970
0
If electronics has been your hobbly or
profession for many years, I'm sure you've
connected two identical linear regulators.
An example would be connecting two 5 amp
LM338 regulators to produce a 10 amp supply.

Reason that parallel power does not work for power supplies: foldback
current limiting. Once one supply hits a limit (takes up too much
load because its voltage was so slightly higher), then foldback
current limiting kicks in. Only solution is a complete power down.
But by that time, the other supply has also entered foldback current
limiting.

Others have explained how to do parallel power supplies complete
with constant tweaking. Of course, that can only work if both
supplies are never outputting anywhere near to 100% load. Again, due
to foldback current limiting.
 
E

Eeyore

Jan 1, 1970
0
John said:
place a low drop out diode on the output of each supply so they dont fight
with each other...

Please advise where I can find these 'low drop-out' diodes !

Graham
 
J

John Barrett

Jan 1, 1970
0
w_tom said:
Reason that parallel power does not work for power supplies: foldback
current limiting. Once one supply hits a limit (takes up too much
load because its voltage was so slightly higher), then foldback
current limiting kicks in. Only solution is a complete power down.
But by that time, the other supply has also entered foldback current
limiting.

Others have explained how to do parallel power supplies complete
with constant tweaking. Of course, that can only work if both
supplies are never outputting anywhere near to 100% load. Again, due
to foldback current limiting.

depends on if the PSU cuts off at the current limit or folds back the
voltage when going over-current -- I dont know about those particular
supplies so its a toss up -- but cheap enough to try :)
 
W

w_tom

Jan 1, 1970
0
depends on if the PSU cuts off at the current limit or folds back the
voltage when going over-current -- I dont know about those particular
supplies so its a toss up -- but cheap enough to try

Intel spec demands that ATX power supplies do what computer power
supplies did even 30 years ago. That spec demands a computer power
supply perform foldback current limiting - and even puts a number (I
have forgotten it) to that current.

Foldback current limiting is why an overloaded power supply (with a
slightly higher voltage) cuts out - leaving the other supply to
provide all power and then also enter current limiting.
 
L

legg

Jan 1, 1970
0
If electronics has been your hobbly or
profession for many years, I'm sure you've
connected two identical linear regulators.
An example would be connecting two 5 amp
LM338 regulators to produce a 10 amp supply.

I've never done this with identical switchmode
regulators, and I'm wondering if it's practical
or even possible?

I've got two 20 volt - 3 amp brick style (also
called table-top) switching power supplies.
I'd like to combine the ouputs. In effect,
you would end up with an 20 volt - 6 amp
supply.

They are manufactured by Pihong.
Model No. PSA60W-200.

The use of bricks in parallel and series is a standard technique to
produce redundancy and longer MTBF. It does require consideration for
the topology used and the fault-isolation required.

Units with active output rectification must be orring diode isolated
in the parallel case, as must be individual crowbar networks and
regulation networks.

Techniques slope regulation can allow effective sharing without actual
p-string sensing circuitry. Active orring diodes can also be
configured with fixed forward voltage drops, easing centering
adjustment requirements.

Best way to start is to look over the MFR app notes. If they do not
supply typical applicatuion data, move on to another mfr.

RL
 
L

legg

Jan 1, 1970
0
Reason that parallel power does not work for power supplies: foldback
current limiting. Once one supply hits a limit (takes up too much
load because its voltage was so slightly higher), then foldback
current limiting kicks in. Only solution is a complete power down.
But by that time, the other supply has also entered foldback current
limiting.

Others have explained how to do parallel power supplies complete
with constant tweaking. Of course, that can only work if both
supplies are never outputting anywhere near to 100% load. Again, due
to foldback current limiting.

There is no reason why an SMPS needs to be folded back while limiting.

RL
 
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