Active PFC?

[Computers911]

Hello:

I'm hoping to save energy by replacing my current PS with one which has
Active PFC. But before I do, I'd like to figure out if it's worth while.
How do I determine how much energy is currently being used by my computer?
The company how's product I'm interested in purchasing is called
Thermaltake...they were on help in explaining to me the energy savings. The
product info. is @ the following link:

http://www.thermaltake.com/products/purepower/w0006r.htm

Thanks in advance....

 

[Chris Oates]

Hello:

I'm hoping to save energy by replacing my current PS with one which has
Active PFC. But before I do, I'd like to figure out if it's worth while.
How do I determine how much energy is currently being used by my computer?
The company how's product I'm interested in purchasing is called
Thermaltake...they were on help in explaining to me the energy savings. The
product info. is @ the following link:

http://www.thermaltake.com/products/purepower/w0006r.htm

Non-PFC offers around 0.5~0.6 PF (Power Frequency), 40%~50% power lost.

they talk rubbish which doesn't inspire
much confidence

 

[ctsbillc]

Power factor isn't about efficiency, it is about the way the power supply
draws current, which without PFC distorts the power waveform and presents a
bad load to the generator.

You will not see any dollar savings with a PFC supply, it will use a bit
more power, but it will present a cleaner load to the power grid.

Bill C

 

[Chris Oates]

Power factor isn't about efficiency, it is about the way the power supply
draws current, which without PFC distorts the power waveform and presents a
bad load to the generator.

You will not see any dollar savings with a PFC supply, it will use a bit
more power, but it will present a cleaner load to the power grid.

In the UK if you had enough equipment to significantly
lower your power factor you can (on the correct tarrif)
install power factor correction & save money.
(one PC won't do it)

 

[Computers911]

Ok, so if there is no dollar savings in an Active PFC power supply, why is
the manufacturer of the power supply talking about lost power? I don't
understand the terminology.

Say for example that I have two power supplies. Each is rated at 360Watts.
One is non-PFC and the second has Active PFC. According to what you said,
they both still use the same amount of power? So the 40-50% power loss
would mean that I can hook up fewer devices to a non-PFC power supply?
Which would mean I could use a lower wattage Active PFC power supply to
support the same number of devices that a non-PFC power supply would
support? If that's right, then I could use a 216Watt Active PFC power
supply to do the same job as a 360Watt non-PFC power supply ( assuming a 40%
power loss on the power supply that's non-PFC )?

I hope the above is correct .... otherwise I'll just give up.

 

[Allen Windhorn]

Ok, so if there is no dollar savings in an Active PFC power supply,
why is the manufacturer of the power supply talking about lost
power? I don't understand the terminology.

Say for example that I have two power supplies. Each is rated at
360Watts. One is non-PFC and the second has Active PFC. According
to what you said, they both still use the same amount of power?...

The one with poor power factor would draw more current, so you
couldn't put as many on the same circuit, or, if large, you might need
a circuit with greater capacity. The extra current drawn by the
non-PFC supply doesn't do any work (it is like reactive current), so
it doesn't add to the output power. The output power would be the
same for both, but the non-PFC one would _appear_ to draw (say) 700
watts if you just looked at voltage and current.

PFC does increase efficiency of the electrical wiring a bit, since
there is lower current, hence lower wiring losses.

Regards,
Allen

 

[Fred Abse]

Non-PFC offers around 0.5~0.6 PF (Power Frequency),

I think you mean "Power Factor"

40%~50% power lost.

Not true, if we're talking power factor, the "lost" power is returned to the
supply each half cycle. The consumer won't be paying for it, if his meter
is properly designed.

Active power factor correction only makes much sense to supply companies,
who want their voltages and currents as nearly in phase as possible.
Unless the load is quite large, the extra losses in wiring won't be more
than a few cents a month.

they talk rubbish which doesn't inspire much confidence

As do most companies playing on the susceptibilities of the average
non-technical punter.

 

[Dave Martindale]

Ok, so if there is no dollar savings in an Active PFC power supply, why is
the manufacturer of the power supply talking about lost power? I don't
understand the terminology.

I suspect that whoever wrote that simply doesn't understand what they
are talking about. A power supply with poor power factor doesn't "lose"
power, but it does draw almost all its power near the peak of the AC
waveform. A PFC corrected supply draws current throughout the AC
waveform. Ideally, current would be proportional to voltage.

Say for example that I have two power supplies. Each is rated at 360Watts.
One is non-PFC and the second has Active PFC. According to what you said,
they both still use the same amount of power?

The 360 watt spec is the maximum output power. With 360 W out, the
input power is somewhat higher - but probably about the same for both
designs. If you reduce the load to 180 W, the input power will also
drop in half (or nearly so). The supply doesn't "use" much power
internally.

So the 40-50% power loss
would mean that I can hook up fewer devices to a non-PFC power supply?

No, both have the same output rating. And the "40-50% power loss" is
nonsense.

Dave