Ok,
Not sure if this should really be EE or perhaps OT...
Now I saw small device set-up at a local retailer connected to a grinder. The
idea was that the device would save electricity, reduce noise and extend the
life of the product. (Sounds too good to be true.)
If I turned on the grinder about five seconds later it would quiet down and
the meter they had their showed less power used. How could/would this work?
And if this really could work by cleaning/manipulating the power on a single
inductive load, how could this work on a whole house?
Here is a link to a whole home unit from the maker of the unit that I saw. http://www.eslainc.com/pp2homeunit.htm
If these are for real, then:
- Why wouldn't all houses, etc. have units of some kind to perform this
function?
- It sounds like something that would only work on inductive loads, like
motors, fans, etc. I would like to get one of these for a greenhouse (many
motors and fans running 24/7) just would like to know some information about
how this could work from somebody who is not attempting to make a sale.
- Would something like this cause me problems if main power failed an a backup
generator kicked on?
- Any place I can read more information about this kind of thing?
____________________________________________
>Ok,
>Not sure if this should really be EE or perhaps OT...
>Now I saw small device set-up at a local retailer connected to a
>grinder. The
>idea was that the device would save electricity, reduce noise and extend the
>life of the product. (Sounds too good to be true.)
>If I turned on the grinder about five seconds later it would quiet down and
>the meter they had their showed less power used. How could/would this work?
>
>And if this really could work by cleaning/manipulating the power on a single
>inductive load, how could this work on a whole house?
>Here is a link to a whole home unit from the maker of the unit that I saw.
>http://www.eslainc.com/pp2homeunit.htm
>
>If these are for real, then:
>- Why wouldn't all houses, etc. have units of some kind to perform this
>function?
>
>- It sounds like something that would only work on inductive loads, like
>motors, fans, etc. I would like to get one of these for a greenhouse (many
>motors and fans running 24/7) just would like to know some information about
>how this could work from somebody who is not attempting to make a sale.
>
>- Would something like this cause me problems if main power failed an a
>backup
>generator kicked on?
>
>- Any place I can read more information about this kind of thing?
It's apparently possible to save some money (true power) by altering (using
phase
control, I think) the input power to an induction motor that is LIGHTLY
LOADED (key point).
If it's running at full load, there's nothing that can be done, the motor
will work as it's been designed and optimized to do. This really limits the
applications (many things like fans and AC compressors run flat out and just
are switched on and off). Try googling for more info. This isn't new, the
devices have been on the market here for perhaps 7 or 8 years.
They are NOT new. There ARE commercial units that do this same thing
for air compressors and other high-power motors. They are usually called
"phase correction" modules. The actual gain is negligible for a homeowner;
you'd probably NEVER get your investment back.
Usually, when something is too good to be true, it isn't.
>Ok,
>Not sure if this should really be EE or perhaps OT...
>Now I saw small device set-up at a local retailer connected to a grinder. The
>idea was that the device would save electricity, reduce noise and extend the
>life of the product. (Sounds too good to be true.)
>If I turned on the grinder about five seconds later it would quiet down and
>the meter they had their showed less power used. How could/would this work?
>
>And if this really could work by cleaning/manipulating the power on a single
>inductive load, how could this work on a whole house?
>Here is a link to a whole home unit from the maker of the unit that I saw.
>http://www.eslainc.com/pp2homeunit.htm
>
>If these are for real, then:
>- Why wouldn't all houses, etc. have units of some kind to perform this
>function?
>
>- It sounds like something that would only work on inductive loads, like
>motors, fans, etc. I would like to get one of these for a greenhouse (many
>motors and fans running 24/7) just would like to know some information about
>how this could work from somebody who is not attempting to make a sale.
>
>- Would something like this cause me problems if main power failed an a backup
>generator kicked on?
>
>- Any place I can read more information about this kind of thing?
At 10:34 PM 12/19/2004 -0700, you wrote:
>They are NOT new. There ARE commercial units that do this same thing
>for air compressors and other high-power motors. They are usually called
>"phase correction" modules. The actual gain is negligible for a homeowner;
>you'd probably NEVER get your investment back.
>
>Usually, when something is too good to be true, it isn't.
>
>--Bob
If the motor operates at light load, motor internal losses can be lowered.
If it most of the time operates at high load, total loss will probably be higher because of loss in the device.
As with variable frequiency drives i believe it have the same problem: due to switching ther wil be induced currents in the whole motor, and through bearings, so they may break sooner than else. Therefor there are available isolated bearings, and motors with them originally installed too, for variable frequency drive.
Variable frequency drive of motors will often save much power, especially in fan and pump installations, where it saves lot of power compared to on/off. Another application is heat pumps: running continously at lower speed makes less temperature loss in heat exchangers. And lower noise too. Beware problems in machines not intended for low speed: such as water lubrication in submersible pumps, and lobrication oil circulaiton in heat pumps!
For ventilation great savigs can be done, and lower noise than running fans on/off or fullspeed + vanes. There is a Swedish firm making a VFD with true sine output for extra low noise, high efficiency, and no bearing problems.
http://www.nfodrives.se I have been on hands on demonstration and they are really awesone! Really something for your greenhouse i think. More expansive than old (current standard) type VFD, but worth it in longer motor life etc (reports say). Also, the sensorless feedback on theese are really good.
IIRC, USA government had/have some economic support for industries applying VFD!
>> If you have access to a wattmeter maybe you could try one and see what
>> difference it makes (and return it if it doesn't make sense).
> Is what the electricity counter counts actually the watts that a wattmeter
> measures? Probably depends on the wattmeter... and the type of counter?
Electricity meters for homes are true watt meters. In the traditional
electro-mechanical ones with a rotating wheel the speed of the wheel is the
product of line voltage and instantaneous amps.
Fan wattage with and without an "energy saver" could be measured by counting
the wheel revolutions over a selected period of time when the fan is the
only load. Meters have a calibration figure on them (rotations per kWh)
allowing power consumption to be calculated using a stop watch and
(optionally) a simple calculator.
RM
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Checked by AVG Anti-Virus.
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mmynsted_news wrote:
> Now I saw small device set-up at a local retailer connected to a
> grinder. The idea was that the device would save electricity, reduce
> noise and extend the life of the product. (Sounds too good to be true.)
> If I turned on the grinder about five seconds later it would quiet down
> and the meter they had their showed less power used.
And what did the meter do without the device attached? It makes sense that
power drain of a motor goes down once it gets up to speed. Also, was the
meter measuring current or true power? If just current, then it doesn't
tell you much useful. Something like a power factor corrector (or a bank of
capacitors if properly matched) can reduce the current but not the power.
The motor is probably most efficient with a sine wave in, which is what the
bare power line was providing. If so, I can't see what you could put in
front of the motor to reduce the power in at the same power out.
One possibility is that the device is specific to the type of motor in the
grinder. Maybe it watches the motor speed and tries to maintain it a little
slower than it would be at full voltage with no load. When the motor slows
down due to load, the device increases the voltage up to the full line
voltage. Note that this is pure speculation on my part. If this is true,
then the device would only help when motors are running idle in between
being called upon to put out significant power.
All in all it sounds like snake oil to me. If it does reduce power
consumption at all, it certainly only does so in limited circumstances or
reduces the output power of the devices being driven. This could actually
damage some loads.
*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________
Gerhard Fiedler wrote:
> Is what the electricity counter counts actually the watts that a
> wattmeter measures?
Electric meters used by utilities to measure power usage measure true power,
and are quite good at it. Whether that's what you mean by "electricity
counter" only you can say. And whether that matches the watts that a watt
meter would measure depends on the quality of the watt meter.
Electric meters are very good power meters because they use basic physics to
integrate voltage times current. This makes them very difficult to fool.
Note that the magnetic force between two separate windings is the product of
the current thru each of the windings. Supply delivered voltage to one
winding and delivered current to the other, then use the force to run a
motor. The total turns of the motor is proportional to the total true power
delivered.
*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________
> >> If you have access to a wattmeter maybe you could try one and see what
> >> difference it makes (and return it if it doesn't make sense).
>
> > Is what the electricity counter counts actually the watts that a wattmeter
> > measures? Probably depends on the wattmeter... and the type of counter?
>
> Electricity meters for homes are true watt meters. In the traditional
> electro-mechanical ones with a rotating wheel the speed of the wheel is the
> product of line voltage and instantaneous amps.
And they usually don't care about reactive power. The wheel doesn't
turn if you connect a capacitor or an inductor to the AC line.
Now if I could get a circuit to transform my resistive loads in
capacitive or inductive ones... ;-)
>> Electricity meters for homes are true watt meters. In
>> the traditional electro-mechanical ones with a rotating
>> wheel the speed of the wheel is the product of line
>> voltage and instantaneous amps.
>And they usually don't care about reactive power. The
>wheel doesn't turn if you connect a capacitor or an
>inductor to the AC line.
Huh? All the old mechanical meters I came across needed the current in phase
with the voltage to make the dial turn correctly. Connecting a hugely
inductive load such as an arc welder transformer could make the dial turn
backwards. The power authority frowned on this unless you had arrangements
with them for proper power factor correction.
>>>Electricity meters for homes are true watt meters. In
>>>the traditional electro-mechanical ones with a rotating
>>>wheel the speed of the wheel is the product of line
>>>voltage and instantaneous amps.
>>>
>>>
>>And they usually don't care about reactive power. The
>>
>>
>
>
>
>>wheel doesn't turn if you connect a capacitor or an
>>
>>
>
>
>
>>inductor to the AC line.
>>
>>
>
>
>
>Huh? All the old mechanical meters I came across needed the current in phase
>with the voltage to make the dial turn correctly. Connecting a hugely
>inductive load such as an arc welder transformer could make the dial turn
>backwards. The power authority frowned on this unless you had arrangements
>with them for proper power factor correction.
>
At 09:58 AM 12/20/2004 -0200, you wrote:
>Spehro Pefhany wrote:
>
> > If you have access to a wattmeter maybe you could try one and see what
> > difference it makes (and return it if it doesn't make sense).
>
>Is what the electricity counter counts actually the watts that a wattmeter
>measures? Probably depends on the wattmeter... and the type of counter?
>
>Gerhard
Residential kw-h meters measure actual energy. That's a unique number
given only weak assumptions (measured over an integer number of cycles
for a periodic waveform- and it tends toward the real number very fast
anyhow). It's the integral over time of the true power, which is the
product of instantaneous voltage and instantaneous current. Not so easy to
do electronically; they do it electromagnetically/electromechanically in
traditional kW-h meters.
In commercial/industrial situations there might be a surcharge if the
power factor is far off resistive (meaning that useless current is
flowing through power company equipment, increasing system losses), but
that's another matter (capacitors can fix that).
>Huh? All the old mechanical meters I came across needed the current in phase
>with the voltage to make the dial turn correctly. Connecting a hugely
>inductive load such as an arc welder transformer could make the dial turn
>backwards.
It should only be able to turn backward if you're actually transferring
energy back into the grid. A simple inductor won't do that (the average over
a cycle is zero energy transferred either way for a perfect inductance or
capacitance, real ones don't do as well as that, of course). You'd need a
generator or something like that.
The rotating disk meters don't seem to have a one way cog. Before
installing a time-of-use meter, the new PV solar system was merrily
running the disk and indicators backwards. Watching the disk speed up
and slow down on a partly cloudy day was sort of amusing. Admittedly,
I'm easily amused.
Some NASA engineer had a patent for 'motor power management' about 20
years ago. Basically the circuit backed off the power (phase control)
for induction motors being use for actuator appications.
The circuit sensed the current phase lag to restore full power
when the motor was loaded. It saved energy best when used in
variable load situations (like washing machines). It did little
for a steady state load like a furnace fan where one should size
the motor to match the load.
There was a DIY article in Popular Electronics back in the mid '80's.
I seem to recall it resurfacing as a commercial product
in the early '90s but again, went nowhere.
I expect that the patent has now expired so some entrepreneur is
out to make a buck again.
Today's PIC would make it dead easy to build and probably more
efficient too.
> mmynsted_news wrote:
>
>> Now I saw small device set-up at a local retailer connected to a
>> grinder. The idea was that the device would save electricity, reduce
>> noise and extend the life of the product. (Sounds too good to be true.)
>> If I turned on the grinder about five seconds later it would quiet down
>> and the meter they had their showed less power used.
>
>
> And what did the meter do without the device attached? It makes sense that
> power drain of a motor goes down once it gets up to speed. Also, was the
> meter measuring current or true power? If just current, then it doesn't
> tell you much useful. Something like a power factor corrector (or a
> bank of
> capacitors if properly matched) can reduce the current but not the power.
> The motor is probably most efficient with a sine wave in, which is what the
> bare power line was providing. If so, I can't see what you could put in
> front of the motor to reduce the power in at the same power out.
>
> One possibility is that the device is specific to the type of motor in the
> grinder. Maybe it watches the motor speed and tries to maintain it a
> little
> slower than it would be at full voltage with no load. When the motor slows
> down due to load, the device increases the voltage up to the full line
> voltage. Note that this is pure speculation on my part. If this is true,
> then the device would only help when motors are running idle in between
> being called upon to put out significant power.
>
> All in all it sounds like snake oil to me. If it does reduce power
> consumption at all, it certainly only does so in limited circumstances or
> reduces the output power of the devices being driven. This could actually
> damage some loads.
>
>
> *****************************************************************
> Embed Inc, embedded system specialists in Littleton Massachusetts
> (978) 742-9014, http://www.embedinc.com
> It should only be able to turn backward if you're actually transferring
> energy back into the grid. A simple inductor won't do that (the
> average over
> a cycle is zero energy transferred either way for a perfect inductance or
> capacitance, real ones don't do as well as that, of course). You'd need a
> generator or something like that.
>
> Best regards,
>
> Spehro Pefhany --"it's the network..." "The Journey is the
> reward"
Speaking of which, does anyone remember the gimmick that was in Popular
Science among others - claiming to spin your power meter backwards?
Do you remember what it was exactly?
--
---
Martin Klingensmith
nnytech.net
infoarchive.net
Hi all,
I was using a 5 HP motor and driving it with a little air cooled
diesel. The heat from the diesel would heat the house down to about 30
degrees and the meter would spin backward about 1.7 Kwh / H. Output of
the motor was about 25 amps @ 240 Power factor was maybe .5 or .6.
> Spehro Pefhany wrote:
>
>> It should only be able to turn backward if you're actually transferring
>> energy back into the grid. A simple inductor won't do that (the
>> average over
>> a cycle is zero energy transferred either way for a perfect
>> inductance or
>> capacitance, real ones don't do as well as that, of course). You'd
>> need a
>> generator or something like that.
>>
>> Best regards,
>>
>> Spehro Pefhany --"it's the network..." "The Journey is the
>> reward"
>
>
> Speaking of which, does anyone remember the gimmick that was in Popular
> Science among others - claiming to spin your power meter backwards?
> Do you remember what it was exactly?
>
> There was a DIY article in Popular Electronics back in the mid '80's.
> I seem to recall it resurfacing as a commercial product
> in the early '90s but again, went nowhere.
> I expect that the patent has now expired so some entrepreneur is
> out to make a buck again.
>
> Today's PIC would make it dead easy to build and probably more
> efficient too.
>
> Robert
>At 02:45 PM 12/20/2004 +0000, you wrote:
>
>
>>Huh? All the old mechanical meters I came across needed the current in phase
>>with the voltage to make the dial turn correctly. Connecting a hugely
>>inductive load such as an arc welder transformer could make the dial turn
>>backwards.
>
>It should only be able to turn backward if you're actually transferring
>energy back into the grid. A simple inductor won't do that (the average over
>a cycle is zero energy transferred either way for a perfect inductance or
>capacitance, real ones don't do as well as that, of course). You'd need a
>generator or something like that.
>
>Best regards,
>
>Spehro Pefhany --"it's the network..." "The Journey is the reward"
>
..mmm.. This has gone through my mind before so you provided the stimulus
to give it a bash.
If a Ferraris-wheel type meter is to run backwards under conditions of high
inductive current, then it would be because the meter itself is not constructed
or tested for accurate running in that state. i.e. The manufacturer hadn't
considered that users might run a lot of such loads, and so ensured the
meter was built to deal with it.
Anyways, I have meters here and a handy welder.
Plugs in.
Meter shows energy consumption ~80 Watts, this gels with the noticeable
heating output of the box when left running.
Unplugs.
If the meter had shown reverse rotation of 80W, then I would still have
unplugged it because letting it run unloaded would have constituted
cheating (i.e. theft) on my part.
Yup.
best regards & happy christmas, John
email from the desk of John Sanderson.
JS Controls, PO Box 1887, Boksburg 1460, Rep. of S. Africa.
Tel/Fax 011 893 4154,
Cell 082 741 6275,
web http://www.jscontrols.co.za
Manufacturer & purveyor of laboratory force testing apparatus &
related products & services.
Replying to my own post
Morgan Olsson 12:13 2004-12-20:
>If the motor operates at light load, motor internal losses can be lowered.
By reducing voltage yes.
But visiting the given link it looks like that divice do phase angle correction to the line. In that case it is not affecting the internal loss in the motor, but reducing line loss by moving current in phase with voltage, thus lowering current, thus lowering line load, thus lowering line loss.
This normally is not measured, and thus not billed for small users, but is for large users and they pay penalty if they pose too high phase angle.
20 years ago in school i visited nearby town electricity center, end thye had *large* caps automatically switched in and out of the town supply high voltage in steps, to compensate for the whole town inductivity. Oil filled switches IIRC.
They told me that some decades ago there used to be large induction motors used instead, not mechanically loaded, with variable DC control of rotor magnetization, and by that the phase angle could be manually corrected. Usually in large industries, placed in a room for itself. Of course it consumed power (100% loss) but in the large picture it saved much more in power plant, transformers and power grid.
> They are NOT new. There ARE commercial units that do this same thing
> for air compressors and other high-power motors. They are usually called
> "phase correction" modules. The actual gain is negligible for a
> homeowner;
> you'd probably NEVER get your investment back.
>
> Usually, when something is too good to be true, it isn't.
The gain and payback for a commercial outfit may be marginal as well.
Back in the 1980's I looked into a company that was selling power factor correction equipment for commercial installations. They would go into a facility like a hospital or a factory, and put on a big show telling them that this magic black box would save them energy. They would install a power factor correction capacitor on the service entrance.
A year later, when the bills did not go down, the client would call them complaining, and they would do a "study". The "study" would show that the usage actually went up 10%, but the power factor correction equipment was saving 10% so that is why the bills didn't change. Typical payback periods were quoted in months.
I pulled out the IEEE references and did the real calculations for power factor correction in some of these facilities. I would come up with numbers like a savings of 0.01% and a payback period of 1500 years. The principle is, if the facility has a low power factor, increasing the PF can reduce I2R losses in the feeder cable. The effect is small, but real.
I had a chance to examine the software this outfit used in these "studies". The way it calculated savings from PFC on the service entrance was to add up the utility bills for a year, and multiply the result by 10%. Olin, please have a field day with this calculation method if you will, I would love to hear your reaction to their "physics".
This outfit was called ETI, Electenergy Technologies. They are still around, and still selling snake oil. Today their power factor correction junk is called "electroflow" and saves, not 10%, but 34%!. Google on it if you want to read more gibberish.
-- Lawrence Lile, P.E.
Electrical and Electronic Solutions
Project Solutions Companies http://www.projsolco.com
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Lawrence Lile wrote:
> I had a chance to examine the software this outfit used in these
> "studies". The way it calculated savings from PFC on the service
> entrance was to add up the utility bills for a year, and multiply the
> result by 10%. Olin, please have a field day with this
I don't know what else you said after that since you sent this paragraph as
one long line and it got truncated somwhere, apparently at 256 characters.
You really should set your mailer to send lines wrapped to lengths in the
72-80 characters range. Long lines are not guaranteed by SMTP or POP3.
*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________
>>They are NOT new. There ARE commercial units that do this same thing
>>for air compressors and other high-power motors. They are usually called
>>"phase correction" modules. The actual gain is negligible for a
>>homeowner;
>>you'd probably NEVER get your investment back.
>>
>>Usually, when something is too good to be true, it isn't.
>>
>>
>
>The gain and payback for a commercial outfit may be marginal as well.
>
>Back in the 1980's I looked into a company that was selling power factor correction equipment for commercial installations. They would go into a facility like a hospital or a factory, and put on a big show telling them that this magic black box would save them energy. They would install a power factor correction capacitor on the service entrance.
>
>A year later, when the bills did not go down, the client would call them complaining, and they would do a "study". The "study" would show that the usage actually went up 10%, but the power factor correction equipment was saving 10% so that is why the bills didn't change. Typical payback periods were quoted in months.
>
>I pulled out the IEEE references and did the real calculations for power factor correction in some of these facilities. I would come up with numbers like a savings of 0.01% and a payback period of 1500 years. The principle is, if the facility has a low power factor, increasing the PF can reduce I2R losses in the feeder cable. The effect is small, but real.
>
>I had a chance to examine the software this outfit used in these "studies". The way it calculated savings from PFC on the service entrance was to add up the utility bills for a year, and multiply the result by 10%. Olin, please have a field day with this calculation method if you will, I would love to hear your reaction to their "physics".
>
>This outfit was called ETI, Electenergy Technologies. They are still around, and still selling snake oil. Today their power factor correction junk is called "electroflow" and saves, not 10%, but 34%!. Google on it if you want to read more gibberish.
>
>-- Lawrence Lile, P.E.
>Electrical and Electronic Solutions
>Project Solutions Companies
>http://www.projsolco.com
>
>---
>Outgoing mail is certified Virus Free.
>Checked by AVG anti-virus system (http://www.grisoft.com).
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>
>
I was under the impression that power factor losses could add up quite
significantly for industrial type installations. The power companies here
(Central USA) mandate that industrial installations are power-factor
corrected. Home users don't have to bother with it, and can apparently
"cheat" the power company of electricity if they run certain loads. (???)
Robert B. wrote:
> I was under the impression that power factor losses could add up quite
> significantly for industrial type installations. The power companies
> here (Central USA) mandate that industrial installations are
> power-factor corrected. Home users don't have to bother with it, and
> can apparently "cheat" the power company of electricity if they run
> certain loads. (???)
No. Non-unity power factor doesn't enable you to take power you don't get
metered for. It does cause the power company to waste power in the
transmission system, which is why the price to large commercial customers is
in part dependent on the worst case power factor over the billing period.
*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________
Low power factor can create extra losses in a long feeder cable. This is especially true for a power company, whose lines may be miles long. Low power factor may also have some other effects on power quality, and of course throwing a capacitor across the line might decouple a few transients. I can imagine there are industrial installations where it would actually pay to install these animals, or where it might be good design. However, there are also scammers in every industry.
-- Lawrence Lile, P.E.
Electrical and Electronic Solutions
Project Solutions Companies http://www.projsolco.com
573-443-7100 ext 221
Thanks to everybody for your insight on this. :-) Looks like it was too good
to be true. I am glad I did not purchase one of these. The greenhouse fans,
pumps, etc. that are of use to me run at 0% = Off, or 100% = On, so I would
be in better shape ensuring I have the right sized motors.
interlog.com Info for manufacturers: http://www.trexon.com
