Kill-a-Watt surprises

[William Sommerwerck]

Its been pointed that you don't really need a watt or watt-hour meter to
save money -- you just turn off things you're not using.

This is not altogether true.

My electric bill was ridiculous, so I started checking. I'd been too lazy to
regularly turn off my A/V system's equipment, which includes a number of
vampire devices.

I was surprised to discover that the Parasound controller pulled 30VA, even
when not turned on. And a Lexicon CP-3plus drew 20VA, simply in standby. As
I rarely use it, I turned the standby switch to "off".

Most of the vampire devices are items I don't use regularly. I'm going to
move them to their own strip, so that they will always be off, except when
actually being used.

 

[William Sommerwerck]

Most of the vampire devices are items I don't use regularly.

You can get an idea just from the temperature of the device when
it is on standby. Cold devices can be ignored. I've found the worst
offender in all my AV equipment is the cable box.

The Parasound was always slightly warm, despite its size, so the power it
pulled was not surprising. But a unit with a "compact" power supply might be
warmer -- in that area -- than a unit that pulls more power, but whose
supply uses a bigger transformer or is further from the cabinet's cover.

 

[UCLAN]

Its been pointed that you don't really need a watt or watt-hour meter to
save money -- you just turn off things you're not using.

This is not altogether true.

My electric bill was ridiculous, so I started checking. I'd been too lazy to
regularly turn off my A/V system's equipment, which includes a number of
vampire devices.

I was surprised to discover that the Parasound controller pulled 30VA, even
when not turned on. And a Lexicon CP-3plus drew 20VA, simply in standby. As
I rarely use it, I turned the standby switch to "off".

Most of the vampire devices are items I don't use regularly. I'm going to
move them to their own strip, so that they will always be off, except when
actually being used.

Or use a strip with separate ON/OFF switches for each outlet.

http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=0688EK2C3B3PRAAMCN2Y

http://tinyurl.com/ybzqx2a

 

[D Yuniskis]

Its been pointed that you don't really need a watt or watt-hour meter to
save money -- you just turn off things you're not using.

This is not altogether true.

No, its true. You just tend to erroneously dismiss things that
you *think* you aren't using -- but really *are*!

My electric bill was ridiculous, so I started checking. I'd been too lazy to
regularly turn off my A/V system's equipment, which includes a number of
vampire devices.

I was surprised to discover that the Parasound controller pulled 30VA, even
when not turned on. And a Lexicon CP-3plus drew 20VA, simply in standby. As
I rarely use it, I turned the standby switch to "off".

Most of the vampire devices are items I don't use regularly. I'm going to
move them to their own strip, so that they will always be off, except when
actually being used.

I've taken to installing power switches in all of the devices
that don't have them. They all *claim* to "sleep" but even
sleeping they often are wasteful.

My current worst offender is the 100Mbps switch. Sure, I can
turn it off -- as long as nothing will have to talk to anything
else! :< (this will be problematic when I switch to VoIP phones;
I guess I'll have to install a low power 10Mbps switch/hub just
for those loads)

 

[William Sommerwerck]

Your electric meter measures watts, not VA. If you know the power

factor, you can convert these VA measurements to watts and eventually
to your cost of electricity. The kill-a-watt meter shows both VA and
watts (as well as PF).

My understanding was that the watt-hour meter actually measure VA-hours. I
asked the electric company once, and that said that was the case. But I
wasn't speaking with an engineer.

 

[D Yuniskis]

My DirecTV R15-500 DVR burns:
Operating power: 22 watts or 42 VA
Standby power: 21 watts or 40 VA
That's only 8 cents per day or $29/year (at $0.15/kw-hr). Much
better. However, the 0.5 power factor isn't very impressive but it's
under 75w so it doesn't have to comply with EN61000-3-2.

Using the revised numbers, yields:
12.5 watts for the 120GB Seagate hard disk
<http://www.seagate.com/docs/pdf/datasheet/disc/ds_barracuda_7200_9.pdf>
3.5 watts for my single LNB
Subtracting from the 22.0 watts total leaves:
6.0 watts for everything else including switcher efficiency.
I don't think there's room for much improvement (except for power
factor correction).

Spin the disk down when it isn;t being used! I.e., the device
knows when it needs to turn itself on to *record* a show. So,
it can conceivably spin down the drive when it knows it does
NOT need to record anything! (it can spin the drive up 6 seconds
before air-time and thus ensure that nothing is "missed").

Likewise, it can see when you are *using* itself to play back
video so it could safely spin down the drive at other times
(and force you to incur that 3 or 4 second spin-up delay
when you *do* grab the remote and start poking at it)

Done properly, even that 6W figure could turn into 1/2W as
the entire device could sleep when not in use -- and just
wake-up when the next "alarm time" is scheduled *or* when
IR is sensed from the remote.

 

[N_Cook]

You can get an idea just from the temperature of the device when it is
on standby. Cold devices can be ignored. I've found the worst
offender in all my AV equipment is the cable box.

I bought a set-top box (UK Freeview) and thought to myself
"hang on a bit the box is as warm with green LED on as on red standby"
I measured consumed watts in both states and standby is 80 percent of the on
state. I put in a hard on/off switch , data held in EEProm or whatever and
no difference in function except programme info pages takes a couple of
minutes to gather

 

[D Yuniskis]

Sure, but I don't have any control over the DirecTV firmware. What I

Of course! My point was that *they* could still make significant
savings in their dessign.

have is what I have to live with. My guess(tm) is that they spin the
disk continuously to improve the operating life of the hard disk
drive. I have servers that run 24x7x365 that never seem to eat a disk

Spin the drives down and then try spinning them back up! :>
(i.e., the stress seems to be on the spin-up)

I think modern drives have really long MTBFs. What kills
disks is the same thing that kills most electronic things: heat.

drive. I have one in the office that's been running continuously
since about 1995. However, the same drives, will die after 3-5 years
with start-stop operation.

I haven't lost a disk in 30 years (touch wood). The drives in my
primary machine have date stamps of 2002. They see a fair bit
of power cycling (since the machine doesn't have a reset button,
the only way to truly reset it is to cycle power and wait for
all the drives to spin up again).

Well, it's not quite so simple. The box downloads firmware updates
and program listings erratically. It also calls home on the phone
line in the middle of the night for pay per view and quality control.

These aren't random events. There is software inside the
box *deciding* when to do these things. So, it could
go to sleep and still have told something to wake it up
at its next scheduled activity.

I can also make record schedule entries via the internet. If the LNB
is powered down, it takes about a minute for things to settle down and
stabilize again. Power consumption can probably be drastically
reduced using some manner of standby mode, but my box is VERY busy,
which means the algorithm may be rather complex and the savings rather

Modern processors have very complex power management features
*in* the processor (SMI). If they aren't being exploited,
it is because the box's manufacturer was just lazy (and had
no incentive to do so!)

limited. If it costs me about $3/month to avoid complications and
extend the life of the hard disk, I would probably pay the price.

I've been moving all of my "software" (movies, music) onto
large disks (several TB) so that I can serve this from a
single machine. I let the drives power down when not in use.
My biggest problem is the network switch that I rely on
for distribution as it can't be powered down.

 

[D Yuniskis]

My understanding was that the watt-hour meter actually measure VA-hours. I
asked the electric company once, and that said that was the case. But I
wasn't speaking with an engineer.

No -- with caveats.

The vast majority of KWHr meters (in the US) are old "motors".
These are tuned electromechanical kludges that are absolutely
amazing in that they work AT ALL! :> And, that they are so
easily mass produced and have such long service lives!

The are typically calibrated at 10% load and 100% load.
And, again, at 50% (lagging) power factor (e.g., 60 degrees).

I *think* that the nature of most loads is such that
they can still claim their 1% accuracy despite all the
perverse loads that have come into being since they
were created (decades ago).

Many electronic KWHr meters are motors outfitted with
mechanisms to "count revolutions". This allows the
"new technology" to benefit from all fo the design
tweeks that the meters have experienced in their history.

It is possible to convert a KWHr meter to a VARHOUR meter
(an RC network in one of the coils, IIRC).

Some newer "solid state" meters can produce a variety of
metrics (VAR, KW, ToU, Q, etc.) as they typically have
access to more data than a regular "motor" would.

I've often wondered how far you can push an old "motor"
in terms of distorting the load. E.g., how would a 120Hz
*impulse* load be registered? But, its just an intellectual
exercise as coming up with a way to make *use* of power
"extracted" in this form would be problematic.

 

[David]

Its been pointed that you don't really need a watt or
watt-hour meter to
save money -- you just turn off things you're not using.

This is not altogether true.

My electric bill was ridiculous, so I started checking.
I'd been too lazy to
regularly turn off my A/V system's equipment, which
includes a number of
vampire devices.

I was surprised to discover that the Parasound controller
pulled 30VA, even
when not turned on. And a Lexicon CP-3plus drew 20VA,
simply in standby. As
I rarely use it, I turned the standby switch to "off".

Most of the vampire devices are items I don't use
regularly. I'm going to
move them to their own strip, so that they will always be
off, except when
actually being used.

I have just two comments on this:

1) If you are a residence, you are metered and billed by
watts (re: real power) rather than volt*amps. Measure the
watts to see the power consumption that actually is part of
your billing.
2) If you live in an area that requires heating your house
for a majority of a year, the power dissipated is added to
the heating of your house during the heating season and
reduces energy consumption from the furnace energy supplier.
The power is not wasted in this situation. This fact is
rarely considered by the media.

David

 

[William Sommerwerck]

My understanding was that the watt-hour meter actually measure VA-hours.
I

That's VARs, not VA-hours. For 'volt-ampere reactive'.

If you can have watt-hours, you can have VA-hours. Both are units of energy.

Is VAR a unit of energy? No, it's a unit of (reactive) power. Energy and
power are not the same.

 

[Jeff Layman]

I bought a set-top box (UK Freeview) and thought to myself
"hang on a bit the box is as warm with green LED on as on red standby"
I measured consumed watts in both states and standby is 80 percent of the
on state. I put in a hard on/off switch , data held in EEProm or whatever
and no difference in function except programme info pages takes a couple
of minutes to gather

What is meant by "standby"? You may think you know (as I thought I did,
too), but it isn't that simple. See here:
http://arstechnica.com/gadgets/news/2009/02/sony-lcd-exceeds-energy-star-power-draw-75-of-time.ars

It's not just Sony. I queried Panasonic about the regular clicking from my
LCD TV, even when it was in "Standby" mode, and also the less-than-green
readings I was getting from a power meter attached to it (15w in standby,
and 30w when it clicked. I do not know what the power factor of the TV is,
so do not know how these figures correlate with Panasonic's stated standby
consumption of 0.3w, but they don't seem very different from those reported
with the Sony). This was their reply:

"In response, I would advise that first please ensure the SETUP menu option
for “auto search in standby” is switched off. (this is in the “System
Update” SETUP menu option.

Turning off this option will also stop intermittent clicking from the TV
that are caused as the internal PSU relays are turned on to allow the
Freeview decoder to work for software updating.

2.) Please note that the set takes approximately 2 minutes for all the PSU
relays to click off and so the power will only read 0.5W after this time.

3.) Ensure that the power meter used can read the power factor of the unit
required to calculate AC power and is using this to calculate power.

4.) Ensure the meter is capable of accurately reading 0.5W; many meters
cannot go this low. Please refer to the meter’s specification."

That reply was open and very helpful, but (a) "auto search in standby" is
the default condition (b) there is no mention of this in the manual (c) I
still do not know how often the TV goes into auto search mode, for how long,
and what the actual power consumption is in this mode.

I have now taken to switching off at the plug when the TV is not in use.
Info on the DTG pages let me know when to leave the TV in standby/autosearch
for an update.

It makes me wonder just how accurate many other low consumption "standby"
figures are.

 

[David Lesher]

My understanding was that the watt-hour meter actually measure VA-hours. I
asked the electric company once, and that said that was the case. But I
wasn't speaking with an engineer.

It measures true watt-hours. A bad PF device will cost you only SLIGHTLY
more in losses than if it had 1.0 PF. [Increased I, ergo more I^2R]

You can look up "Electricity meter" in Wikipedia..

 

[Franc Zabkar]

My understanding was that the watt-hour meter actually measure VA-hours. I
asked the electric company once, and that said that was the case. But I
wasn't speaking with an engineer.

FWIW, Energy Australia responded to my query as follows:

"Most residential classification customers are metered by a spinning
disc meter, or a basic electronic meter which does not have enough
'smarts' in the meter device to enable billing to be carried out at a
KVA pricing.

Currently small customers are billed on KWh pricing, and KVA Demand
pricing usually relates to large commercial and industrial
installations where poor power factor may impact upon the EA network,
and there may be an economic billing benefit in the customer pricing
to ensure that Power factor is closer to Unity."

- Franc Zabkar

 

[Franc Zabkar]

Its been pointed that you don't really need a watt or watt-hour meter to
save money -- you just turn off things you're not using.

This is not altogether true.

My electric bill was ridiculous, so I started checking. I'd been too lazy to
regularly turn off my A/V system's equipment, which includes a number of
vampire devices.

I was surprised to discover that the Parasound controller pulled 30VA, even
when not turned on. And a Lexicon CP-3plus drew 20VA, simply in standby. As
I rarely use it, I turned the standby switch to "off".

Calculate the VA consumed by the X2 EMI suppression capacitor across
the mains terminals.

For example, a 2.2uF cap across a 240VAC 50Hz supply consumes 39.8VA:

http://www.google.com/search?q=240+x+240+x+2+x+pi+x+50+x+2.2E-6

- Franc Zabkar

 

[William Sommerwerck]

My understanding was that the watt-hour meter actually measure VA-hours.
I

FWIW, Energy Australia responded to my query as follows:

"Most residential classification customers are metered by a spinning
disc meter, or a basic electronic meter which does not have enough
'smarts' in the meter device to enable billing to be carried out at a
KVA pricing.

Currently small customers are billed on KWh pricing, and KVA
Demand pricing usually relates to large commercial and industrial
installations where poor power factor may impact upon the EA network,
and there may be an economic billing benefit in the customer pricing
to ensure that Power factor is closer to Unity."

This is really confusing. Looking solely at the second paragraph, the
implication is that industrial metering is at the VAh level, not Wh.

I don't think this person really knows what he's talking about. The fact
that his statements are redundant ("a basic electronic meter which does not
have enough 'smarts' in the meter device") and jargony strongly suggests
this.

Nevertheless, thanks for asking. I think I'll call the Seattle utility
again.

 

[Sylvia Else]

This is really confusing. Looking solely at the second paragraph, the
implication is that industrial metering is at the VAh level, not Wh.

It may well be, and for the reason given, which seems valid.

I don't think this person really knows what he's talking about. The fact
that his statements are redundant ("a basic electronic meter which does not
have enough 'smarts' in the meter device") and jargony strongly suggests
this.

Perhaps a bit clumsy, but I think the word meter is being used in two
different ways. The scribe probably wasn't employed for his writing talent.

Sylvia.

 

[[email protected]]

I used to work for a submetering outfit and Kill-a-watt was cool.
We tried real hard to find as cheap a doppler ultrasound flowmeter
for water and fuel but the lowest we got was two grand.

But my stud finder is ultrasound. THe only difference should be software.


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Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
http://www.panix.com/~vjp2/vasos.htm http://www.facebook.com/vasjpan2
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
[Homeland Security means private firearms not lazy obstructive guards]
[Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]

 

[D Yuniskis]

I used to work for a submetering outfit and Kill-a-watt was cool.

I think there are competing products with better specs (?)

We tried real hard to find as cheap a doppler ultrasound flowmeter
for water and fuel but the lowest we got was two grand.

But my stud finder is ultrasound. THe only difference should be software.

No doubt partly due to market? E.g., someone makes a gizmo
used to check the integrity of (wooden) telephone poles:
attach to pole, wack pole with hammer, "listen" to
vibrations. Cool, eh? No doubt *very* expensive as
there are few companies interested in "telephone poles"
and, those that are, have deep pockets for this sort
of PM!