wat will the power dissipated be???

[cedance]

120v/60hz rate that energy is being dissipated

hi,

i actually dont know if this is a sensible question... nevertheless i ask it here hopin to get myself clear...

say i have a 60 Hz voltage source and a device which draws 50 Hz current from it.. both are cosine functions.. then the integral of their products over the limits are '0' since the frequencies are different. (basic orthoganlity property).. does this mean that there would be no electricity bill for such an appliance??

/cedance

 

[nicleo]

power consumed power dissipated watts

Interesting ...

Do you mean the 60Hz voltage is the AC main (e.g. 120V/60Hz)?

Could you please elaborate more how do you carry out the integration? Thanks

 

[echo47]

ac power dissipated at time

That sounds like homework from my first-year "Circuits and Systems" class.

Your strange device would spend half its time consuming power, and half its time generating power.
Work done is zero, so zero electricity bill.

However, the power company may frown upon what you are doing, and charge you for having a crazy power factor load!

 

[HCM_bucat]

pwer useage power factor formula

I guess the key thing here is the power integration is 0. How can that be?

 

[Big Boy]

physics222project.pdf

It is possible for a device to take power on a 90 degree phase from the voltage. Both capacitors and inductors have this property.

If your load is only capacitive, or inductive, it will only dissipate power because of losses due to it's internal resistance. Appart from that, there can be large current flowing through that load, and take no power.

How this can be is because the voltave vs current is shifted 90 degree. You get the largest current drain where the voltage is zero. And current also get fed back to the source.

In a more day-to-day life (in real-life case), for ordinary applications, or small homes, this doesn't cause problems. However, if done on a larger scale, this can be a bit problematic. Taking current in this manner still put some load on the power company, and when you have a big company, with lots of motors, for examples, the electric co. have to take this into account, because the electric co still have to produce extra power. The electric company then also monitor the currect phase shift, and usually charge what thay call a 'phase penalty'. This is a bit like being charged for taking more than the allowed power, at a higher rate.

The power cables, running from the power facility to the end users, are very long (lots of miles of cables). The higher the frequency, the higher the cables act as an inductor. This is why the frequency is low (50 or 60 Hz), to minimize this problem. Even with low frequencies, with all the power lines, there is still a non-negligable inductances created over those lines. And the power co. have to take this into account. The inductive effect of an inductor can be eliminated by the capacitive effect of capacitors. Capacitors and inductors create an opposite effect. One take current 90 degree leading the voltage sine wave, the other 90 degree lagging the voltage wave. When combined, they cancel each others (they actually resonate togetter, but on the power source, they appear as an inert load). So, the power facilities have huge (and here I say *very huge*) capacitors at their line outputs. So, some people who also knew that thay had large capacitors, and they were thinking that those were to store electricity in case of brief power interruptions, this is a myth. Those caps are really for cancelling the inductive effect of the miles of power cables.

So, this is also why, on transformers, you usually don't see transformers rates like '10W' (10 Watt), but rather '10VA' which stand for 10 Volts-Amps. Although the power is the product of Volts x Amps (basic Ohm law), when applied to non-DC signals, as seen above, Power rating alone is not sufficient to rate the energy transfer capability of a transformer.

 

[djalli]

power dissipated by inductor internal resistance

Here is something: Why you dont collect the free energy from power radiated in air by TV broadcastings, radios?

That power is truly indeed free. It will be small very small actually but imagine how cool is it.

and two pieces of articles to brighten your imaginations

 

[onemilimeter]

wat is power penalty

The power cables, running from the power facility to the end users, are very long (lots of miles of cables). The higher the frequency, the higher the cables act as an inductor. This is why the frequency is low (50 or 60 Hz), to minimize this problem.

Is this the only reason why the AC main power frequency was 'choosen' to be 50Hz or 60Hz? But why not 10Hz or 20Hz? Lower frequency, the eddy current losses at transformer also less. Why 50Hz or 60Hz? Is it choosen 'technically' or because of 'conventionally'?

Why you dont collect the free energy from power radiated in air by TV broadcastings, radios?

This sentence reminded me on RFID or SMART card. If I'm not mistaken, the RFID tag and SMART card both work on this principle, right?


------
What about generated electricity from 'earth magnetic field'? Is anyone doing research on this?
------

 

[djalli]

dissipated power inductor

Why you dont collect the free energy from power radiated in air by TV broadcastings, radios?

This sentence reminded me on RFID or SMART card. If I'm not mistaken, the RFID tag and SMART card both work on this principle, right?


------
What about generated electricity from 'earth magnetic field'? Is anyone doing research on this?
------

True!

I think we leave alone earth magnetic field. Earth magnetic field is weak in short range , you can beat it, hence: notice magnetic levitation trains but this field is extremely powerful when you view/or use from great distances (example moon!).

Not forgeting of how much damage we have done to eco-system. Lets not play with this field otherwise if this field is gone (and it will be gone after some 600 or 800 centuries is predicted) earth is exposed to mercy of sun/cosmos radiation.

 

[cedance]

do dc signals dissipated power?

I guess the key thing here is the power integration is 0. How can that be?

nope... the integral is zero if u integrate two orthogonal functions of different frequency... the catch is not there i suppose... i got a convincing answer thou tha the whole thing is right that no power will be consumed!!! gr8! is it?

However, the power company may frown upon what you are doing, and charge you for having a crazy power factor load

does the company sue u or the government?? ok... but if that is the case... u know for lowering the power dissipated people now use non-sinusoidal functions for both voltages or currents... (if i am right)... which will have the peak power higher but the average power is lesser than the conventional methods... these are all attempts to get the o/p power minimum as possible... so why should they sue?... we generate power for running a device,,, it works disspates no power... right...


/cedance

 

[Borber]

The awerage value of product U*I is zero but the product of rms values gives the generated power because voltage is allways 230V AC and current let's say 1A AC. Power is not dependent on generators frequencies and is about 155W in this case. This is valid for parallel conection of voltage and current generators. I believe we are talking about effective power.

 

[djalli]

Electric companies (in USA) some of them have installed meters they can ping just the meter device if family has no power, any load is being applied,usage etc. In states in Midwest USA it is being applied.

They are far away towards a ferfect AMR automatic meter reading but they are saying they will go forward to this arena.

 

[echo47]

does the company sue u or the government?? ok... but if that is the case... u know for lowering the power dissipated people now use non-sinusoidal functions for both voltages or currents... (if i am right)... which will have the peak power higher but the average power is lesser than the conventional methods... these are all attempts to get the o/p power minimum as possible... so why should they sue?... we generate power for running a device,,, it works disspates no power... right...

No, "sue" is the wrong word. On you next-month's electric bill, they may include an extra charge for your unusual load. Even though your kilowatt-hour meter reads zero, your current flow is still a burden on the electric company by heating up their transmission lines and transformers. They deserve a little money for that power loss.

If your unusual load is relatively small, the electric company probably won't care and won't charge you.

 

[djalli]

If you live in the country you can build possibly 2-3 km wire-wound antenna not very far to power lines go and "obtain" energy from these lines. Can this be detected very much? Or is a fancy imagination nobody will notice?

 

[cedance]

If you live in the country you can build possibly 2-3 km wire-wound antenna not very far to power lines go and "obtain" energy from these lines. Can this be detected very much? Or is a fancy imagination nobody will notice?

similar to this question, i have one... light is an EM wave.. so keepin a magnet near it, does it get deflected?? with a meter can we measure it?? or energy onbtained from it??? is it possible? or u tend to say its very weak em field and so nothing possible.. ???


/cedance

 

[cedance]

Interesting ...

Do you mean the 60Hz voltage is the AC main (e.g. 120V/60Hz)?
Could you please elaborate more how do you carry out the integration? Thanks

the integral is zero.. if so then the only way is the product of the cosine functions is zero.. which is the product of voltage and current.. = power.. so the power consumed is zero.. hope this gets ur doubt cleared.. reg. the integrations the integral of a cos * cos havin two different phases ( or frequencies).. u can always verify them to be '0'.... books on orthogonality properties would have this....

/cedance

 

[me2please]

I agree with echo 47 BUT I think you still have to pay. Why?
I think when your device generate energy back to the system, the meter won't roll backward for you.

 

[nicleo]

If you live in the country you can build possibly 2-3 km wire-wound antenna not very far to power lines go and "obtain" energy from these lines. Can this be detected very much? Or is a fancy imagination nobody will notice?

My lecturer, specialised in power, shared with us his experience he gained from power plant. I still remember he told us that a fluorescent (both end connected to each other using a wire) can be 'turned on' if we put it (with the aid of a long stick) near to transmission line. He said he did it before.

 

[cedance]

I agree with echo 47 BUT I think you still have to pay. Why?
I think when your device generate energy back to the system, the meter won't roll backward for you.

wat if the first half of the time.. the device generated.. and the next half... the generated energy is being used.. instead the thinkin the opposite way.. ofcourse the first time i would consume a little power.. in which the meter is not goin to make that many rotations...


/cedance

 

[flatulent]

Meters based on a rotating disk will run backwards if power is put into the mains from your end. Back in the days of alternate energy some people in California USA would generate energy and put it into the mains. If they used less energy than this the meter would have a lower reading each time it was read. The state passed a law allowing this and also required the utility company to credit the house bill at a rate specified which was less than the rate charged for using energy.

The idea behind this was that it eliminated the storage battery cost and pollution from disposing of lead when the batteries ran out of storage capacity.

 

[me2please]

This is interesting! I never know exactly how the meter works.
Do you have any document that can help me learn more about
the meter, flatulent (or others)? 8O