Generators and switch mode power supplies.

[Phil Allison]

"JosephKK"

Power factor correction and harmonic suppression are two different
things.

** Not in the context or electronic loads on the AC supply - pal.

Here they are then one and the same.

It is just convenient that typical PFC circuits also reduce
harmonics.

** The WHOLE PURPOSE of an active PFC circuit is eliminate harmonic
currents from the AC supply - pure luck that making the current draw a
sine wave corrects the power factor too.



...... Phil

 

[[email protected]]

"JosephKK"


** Not in the context or electronic loads on the AC supply   -  pal.

    Here they are then one and the same.


**  The WHOLE  PURPOSE of an active PFC  circuit is eliminate harmonic
currents from the AC supply  -  pure luck that making the current draw a
sine wave corrects the power factor too.

.....    Phil

Gee folks it's all right here
http://en.wikipedia.org/wiki/Power_factor

I quote:
In circuits having only sinusoidal currents and voltages, the power
factor effect arises only from the difference in phase between the
current and voltage. This is narrowly known as "displacement power
factor". The concept can be generalized to a total, distortion, or
true power factor where the apparent power includes all harmonic
components. This is of importance in practical power systems which
contain non-linear loads such as rectifiers, some forms of electric
lighting, electric arc furnaces, welding equipment, switched-mode
power supplies and other devices.

so reducing harmonic currents DOES actually improve power factor.

Mark

 

[Phil Allison]

<[email protected]
"Phil Allison"

"JosephKK"


** Not in the context or electronic loads on the AC supply - pal.

Here they are one and the same.


** The WHOLE PURPOSE of an active PFC circuit is eliminate harmonic
currents from the AC supply - pure luck that making the current draw a
sine wave corrects the power factor too.

Gee folks it's all right here
http://en.wikipedia.org/wiki/Power_factor


** You should have quoted this section on ACTIVE PFC.

http://en.wikipedia.org/wiki/Power_factor#Active_PFC



I quote:
In circuits having only sinusoidal currents and voltages, the power
factor effect arises only from the difference in phase between the
current and voltage. This is narrowly known as "displacement power
factor". The concept can be generalized to a total, distortion, or
true power factor where the apparent power includes all harmonic
components.


** Pedantic drivel.

The DEFINITION of "power factor " is simply

PF = watts / VA.

Both the V and A in " VA" are defined as being the * rms values * of the
quantities.

So, when the current waveform is peaky instead of sine wave, it's rms value
increases significantly for the same power consumption.

So VA gets bigger than watts and hence the PF is poor.



...... Phil

 

[[email protected]]

<[email protected]
"Phil Allison"









Gee folks it's all right herehttp://en.wikipedia.org/wiki/Power_factor

**  You should have quoted this section on ACTIVE  PFC.

http://en.wikipedia.org/wiki/Power_factor#Active_PFC

I quote:
In circuits having only sinusoidal currents and voltages, the power
factor effect arises only from the difference in phase between the
current and voltage. This is narrowly known as "displacement power
factor". The concept can be generalized to a total, distortion, or
true power factor where the apparent power includes all harmonic
components.

** Pedantic drivel.

The DEFINITION of  "power factor "  is simply

PF   =  watts  / VA.

Both the V and A  in  " VA" are defined as being the * rms values * of the
quantities.

So, when the current waveform is peaky instead of sine wave, it's rms value
increases significantly for the same power consumption.

So VA gets bigger than watts and hence the PF is poor.

.....    Phil- Hide quoted text -

you just agreed with me..

I said removing harmonics DOES actually improve power factor.



Mark

 

[Phil Allison]

<[email protected]>

you just agreed with me..


** No I DID NOT !!!!

YOU MORONIC FUCKING ASS

**** the HELL OFF

TROLL !!




...... Phil

 

[[email protected]]

x-no-archive

<[email protected]>

you just agreed with me..

** No  I  DID NOT  !!!!

 YOU  MORONIC   FUCKING  ASS

  ****  the HELL OFF

  TROLL   !!

.....  Phil

bye bye

 

[Frithiof Jensen]

Well, usually switcher has a full-wave rectifier and a smoothing cap
at the input. This means it probably works fine even with DC voltage.
The PC and similar stuff should be happy.

Anything with a rectifier/capacitor input will not like square-wave much -
the peak currents in the rectifiers will be very large! Probably squares
will also mess with the tiny silicon brain of any power factor correction
logic . ;-)

Stuff that runs through transformers may not like square wave.

You could run it through a good UPS (the kind that rectifies and
re-generates
AC) to get good regulation and waveform.

A very good idea IMO.

 

[Richard The Dreaded Libertarian]

I assume that's related to the harmonic load represented by switch mode
power supplies.

Circuits for significantly improving the harmonic performance have been
around for a decade, but I suppose little will happen until legislation
requires their use.

If the idea was any good, you wouldn't have to impose it by force of arms.

Thanks,
Rich

 

[Sylvia Else]

Anything with a rectifier/capacitor input will not like square-wave much
- the peak currents in the rectifiers will be very large!

All the circuits I've seen have had a resistor in series to limit the
inrush current at turn on, and this resistor would also limit rectifier
currents when the gear is operated on a square wave.

Probably

squares will also mess with the tiny silicon brain of any power factor
correction logic . ;-)

I certainly wondered about that. The specs for my UPS (A Sola 325) say
"Load Compatability: Can support 100% power factor corrected,
switch-mode power supply load."

But when running on its batteries, it produces what looks to be a bulk
standard "modified sine wave".

Sylvia.

 

[Sylvia Else]

If the idea was any good, you wouldn't have to impose it by force of arms.

It's a classic example of an external cost. Those using equipment that
imposes harmonic losses on the infrastructure don't pay for the costs
they cause. Instead, those costs are shared by all users of the
infrastructure.

Markets almost never internalise external costs unless they are forced
to, regardless of the overall benefits of doing so. It takes legislative
action.

So the notion that the idea wouldn't have to be imposed if it were any
good is false.

Sylvia.

 

[Phil Allison]

"Sillier than Anyone Else"

"TheM"

All the circuits I've seen have had a resistor in series to limit the
inrush current at turn on, and this resistor would also limit rectifier
currents when the gear is operated on a square wave.

** That resistor will likely be sized to withstand the heat generated by a
few switch on cycles per minute.

BUT with a square shaped supply voltage, there will be 100 ( or 120 in the
USA) short current surges per SECOND !!

The rms value of such a current pulse stream is very high and so smoke the
resistor and or other components like diodes, filter chokes and filter
electros.

As the use of "modified square wave" in UPS designs is standard AND the
use of UPSs with PCs very common, all PC supplies and accessories have to be
able to tolerate this scenario.

But there is no obligation on the maker's of other classes of device
employing SMPS to allow for it at all.



...... Phil

 

[JosephKK]

It's a classic example of an external cost. Those using equipment that
imposes harmonic losses on the infrastructure don't pay for the costs
they cause. Instead, those costs are shared by all users of the
infrastructure.

Markets almost never internalise external costs unless they are forced
to, regardless of the overall benefits of doing so. It takes legislative
action.

Almost right. Profit seeking organizations (especially corporations)
and even some not-for-profit organizations have an obvious vested
interest in externalizing all costs possible. When these
organizations participate in a market they seek to maximize the
externalization of cost by pushing those costs onto the purchasers of
their products and services. This is why mining, refining,
manufacturing, and many other organizations were (and are in China) so
cavalier about pollution and using/selling substandard materials. The
organization is purely chasing the (the most result/effect from the)
holy yuan/franc/mark/dollar/peso as demanded by the
stakeholders/stockholders. When the problems created by externalizing
the costs of doing things most cheaply instead of cleaner ways, the
market reacts with many tools, including boycotts, mass plaintiff
lawsuits and driving government regulation and legislation.
Unfortunately, governments being what they are rarely hit the mark and
usually under/over regulate.

 

[Sylvia Else]

Almost right. Profit seeking organizations (especially corporations)
and even some not-for-profit organizations have an obvious vested
interest in externalizing all costs possible. When these
organizations participate in a market they seek to maximize the
externalization of cost by pushing those costs onto the purchasers of
their products and services. This is why mining, refining,
manufacturing, and many other organizations were (and are in China) so
cavalier about pollution and using/selling substandard materials. The
organization is purely chasing the (the most result/effect from the)
holy yuan/franc/mark/dollar/peso as demanded by the
stakeholders/stockholders. When the problems created by externalizing
the costs of doing things most cheaply instead of cleaner ways, the
market reacts with many tools, including boycotts, mass plaintiff
lawsuits and driving government regulation and legislation.
Unfortunately, governments being what they are rarely hit the mark and
usually under/over regulate.

In the context of harmonic loads, the issue is essentially technical.
Beyond second order effects such as needing to mine more metal to make
the transmission cables, there wouldn't be much for consumers to care
about, except that they have to pay more for electricity. I can't see
market action such as boycotts and the like coming to pass. Few
consumers are even going to hear about the issue, let alone understand it.

Sylvia.

 

[Sylvia Else]

"Sillier than Anyone Else"

** That resistor will likely be sized to withstand the heat generated by a
few switch on cycles per minute.

BUT with a square shaped supply voltage, there will be 100 ( or 120 in the
USA) short current surges per SECOND !!

The rms value of such a current pulse stream is very high and so smoke the
resistor and or other components like diodes, filter chokes and filter
electros.

The resistor is sized to handle the energy it has to accept during the
turn on inrush. That isn't a power issue. However, given that such
resistors are typically physically quite large, they also have an
ability to dissipate a reasonable amount of power.

On the face of it, a true square wave input wouldn't trouble the
resistor in a basic SMPS at all, since the resistor would be dissipating
less power than under normal operation. A rectified square wave is
essentially pure DC.

With a modified sine wave, it comes down to how much sag occurs on the
capacitor during the time the input is zero. The greater the sag, the
more likely it is that the resistor will fail.

I can't see why the current should trouble rectifiers. They have to
handle the inrush current, as limited by the resistor, and their power
dissipation is mainly a function of the total charge going through them,
not current waveform.

Once you bring in filter electronics, all bets are off.

Sylvia.

 

[Frithiof Jensen]

All the circuits I've seen have had a resistor in series to limit the
inrush current at turn on, and this resistor would also limit rectifier
currents when the gear is operated on a square wave.

Well, you go right ahead then - The Whip Teaches (some people)

 

[Phil Allison]

"Sillier than Anyone Else"

The resistor is sized to handle the energy it has to accept during the
turn on inrush. That isn't a power issue.

** Of course it IS a POWER RATING issue

- you crazy bitch.

With a modified sine wave, it comes down to how much sag occurs on the
capacitor during the time the input is zero. The greater the sag, the more
likely it is that the resistor will fail.

** Correct.

The worst case scenario is a small SMPS running on a high capacity UPS.

SMPS that use an NTC thermistor instead of a resistor are in even more
trouble.

I can't see why the current should trouble rectifiers. They have to handle
the inrush current, as limited by the resistor,

** Just a singe, large current surge with plenty of time to cool afterwards.

Power rectifier diodes have large, single surge ratings.

But you have never looked up the maker's specs.

and their power dissipation is mainly a function of the total charge going
through them, not current waveform.

** BOLLOCKS.

Diode heat dissipation at mains frequencies is entirely a function of
current.

Once you bring in filter electronics, all bets are off.

** Does not stop you posting more pedantic tripe though -
does it???




...... Phil

 

[Nobody]

Almost right. Profit seeking organizations (especially corporations)
and even some not-for-profit organizations have an obvious vested
interest in externalizing all costs possible. When these
organizations participate in a market they seek to maximize the
externalization of cost by pushing those costs onto the purchasers of
their products and services.

Almost right.

To externalise costs, you have to push them onto the general public.
Pushing costs only onto your customers puts you at a competitive
disadvantage.

If legislation pushes a cost onto the manufacturer, it becomes a
manufacturing cost, no different to the cost of raw materials or labour.
Whether it gets pushed onto the customer or eats into the manufacturer's
profit margin depends upon the degree of competition.

 

[Sylvia Else]

"Sillier than Anyone Else"


** Of course it IS a POWER RATING issue

- you crazy bitch.

The resistors used in such circuits have ratings in Joules, reflecting
the fact that the problem is one of energy, not power.

** Correct.

The worst case scenario is a small SMPS running on a high capacity UPS.

SMPS that use an NTC thermistor instead of a resistor are in even more
trouble.




** Just a singe, large current surge with plenty of time to cool afterwards.

Power rectifier diodes have large, single surge ratings.

But you have never looked up the maker's specs.

Yup. Have. They tend to talk about average current.

** BOLLOCKS.

Diode heat dissipation at mains frequencies is entirely a function of
current.

Some amount of charge is removed from the capacitor during a half-cycle.
That charge has to be replaced over the period of a half-cycle, and has
to come through the rectifier. The energy dissipated in the rectifier in
that time is the charge times the rectifier's forward voltage. The
latter of course is not totally fixed, but rises somewhat with current,
so the power dissipation also rises somewhat if the charge is transfered
in a shorter time. All the same, unless the rectifier is normally being
run close to its thermal limit (which would hardly be good design), I
would expect it to survive.

Sylvia.

 

[Phil Allison]

"Stupider than Anyone Else Alive "

The resistors used in such circuits have ratings in Joules,

** TOTAL BOLLOCKS !!!

Yup. Have. They tend to talk about average current.

** Wrong spec - IMBECILE !

Some amount of charge is removed from the capacitor during a half-cycle.
That charge has to be replaced over the period of a half-cycle, and has to
come through the rectifier. The energy dissipated in the rectifier in that
time is the charge times the rectifier's forward voltage.

** Pedantic TWADDLE.

Diode forward voltage ( Vf) is not a fixed number - it is a function of
both current and chip temperature.

Diode dissipation is the product of Vf & If at any instant.

YOU KNOW FUCKING NOTHING !!!

Bloody Google monkey.



...... Phil

 

[Sylvia Else]

Almost right.

To externalise costs, you have to push them onto the general public.
Pushing costs only onto your customers puts you at a competitive
disadvantage.

If legislation pushes a cost onto the manufacturer, it becomes a
manufacturing cost, no different to the cost of raw materials or labour.
Whether it gets pushed onto the customer or eats into the manufacturer's
profit margin depends upon the degree of competition.

Where all the competing products were previously externalising the cost,
and all now have to internalise it, the cost must inevitably be passed
on to the consumer, because there's no change in competition.

Sylvia.