[freakmuzik]

Guys, I recently went for an exhibition conducted by Manorama ("Veedu" magazine) especially for home appliances and decorations, etc. In one such stall, I found a guy sitting with 3 tube lights connected to a extension cord and there was this product called DeEnergia advertised as a PF corrector. It's a small adapter like thing (looks quite like your All out machine). There was amp meter showing 0.6 amps for three tubes which is correct. As soon as he plugged in this device into another socket, the reading came down to 0.4ampere!

When asked, he said this thing cut's the electrical leakage that also gets into the meter reading while completing the circuit. By this, that guy assures a savings of upto 30% of electricity by connecting this to any one plug socket in our homes! I have no clue about electrical appliances and how this works or whether it even works. Can the gurus please share your thoughts?

They have a website which doesn't have any proper pics or anything - http://energysaverindia.com/

The MRP shown is Rs.2999/- but then they were selling it for Rs.1500/- and I'm attaching a pic of the box. Sorry that I couldn't take pics of the device.

[mayuresh]

Power factor correction as a concept is right. Most of the real life work load is inductive (such as anything that contains motors, tubelights with chokes etc). This draws more current to meet the same power requirement.

Note that more current doesn't directly mean more power in the same proportion. But more current does lead to increase in the losses due to wire resistance etc.

Power factor correction devices are nothing but capacitors (a type of load with opposite effect of inductive).

Some of the better quality devices (fans, refrigerators) might deploy builtin capacitors for good power factor.

For industrial workloads, which is heavily inductive, capacitor banks are deployed for power factor correction.

In fact most electricity companies measure your power factor and fine you if it falls too low. (In Maharashtra state's bill you can see a column for power factor fine. I have never seen this getting triggered in household bills.)

For household workload whether this makes any real difference to the bill or not? I am unsure. May be those who tried can confirm.

[Samurai]

Power Factor correction does save a lot on your bill. PF basically tells you how efficiently you are using the power. Anybody who owns a HT yard, that means responsible for maintaining their own transformer, have to maintain PF above 0.9 value. We have a row of capacitor banks at my office to maintain the PF. We used to get big fines every month until we learned to maintain our PF. Our electrician takes PF reading everyday at the transformer and logs it. Happy to say we maintain it above 0.95 most of the time.

Meanwhile, people drawing power from LT transformers don't have to maintain PF. That is your typical commercial building or domestic buildings, where the PF reading can be as low as 0.7 some times.

You can use this calculator to find the actual current drawn. Notice that current (AMP) varies with PF even if W and V are held constant. Your power bill is based on current drawn. By improving the PF, you can reduce your power bill. But I am not sure whether a plug-able device can work as a capacitor bank. Need to look at the circuit and read some explanations.


This is a view from our internal home grown power management web:

[mayuresh]

Originally Posted by Samurai

Your power bill is based on current drawn.Attachment 1305274

Beg to differ. The electricity meter is an energy meter or KWH meter. The bill depends on the energy consumed rather than current drawn.

How a poor power factor increases the bill is as follows:

Increase in current due to poor power factor does not increase power consumption in the device. But higher values of current increase the amount of loss in overcoming the resistance of wires. Losses are proportional to square of the current, so they increase quite rapidly if current increases.

If you assume wires with no resistance, poor power factor will not lead to loss, since the power consumed is V*I*PF - higher current but same consumption.

[Samurai]

Originally Posted by mayuresh

Increase in current due to poor power factor does not increase power consumption in the device.

Did I say that? I only said it increases current drawn. If you look at the graph, the power consumption ratio refers to the PF value, the actual usage.

Originally Posted by mayuresh

Beg to differ. The electricity meter is an energy meter or KWH meter. The bill depends on the energy consumed rather than current drawn.

This is what I am not sure about. The common domestic meters at home, do they compensate for PF and read correct consumption? It has been over 25 years since I studied electric measuring devices.

In the office HT yard, I have a hi-tech meter with many different read-outs, so I know it handles it correctly.

[amitk26]

seeing the form factor of the device looks like they are using ultracapacitor.
Till few years ago capacitor with high capacitance used to be big and bulky but n ow with improvements in material science the form factor has reduced.

Theoretically connecting in parallel ( inserting in plug point) should work.

I studied electrical many years ago as part of electronics egg degree, so don't remember correctly but , Suppose there is no inductive load and we put a big capacitor what happens ?



Apparent power = sq root of ( reactive power ^ 2 + true power ^2)

And reactive power = inductive - capacitive

So in absence of inductive load (only LED lights or electronic equipments) this should consume more power

[Samurai]

Originally Posted by amitk26

Suppose there is no inductive load and we put a big capacitor what happens ?
.
.
So in absence of inductive load (only LED lights or electronic equipments) this should consume more power

I remember asking these questions 7 years back while trying to understand how to use the capacitor bank, which we have to manually adjust according to load. Just don't remember the answers any more. Fortunately the electrician remembers the procedure since it is his job to maintain PF.

[ampere]

Will try to read more on the main topic.

But as far as power factor aspect goes:

Its the indication of impedance of a system which would consume a resistive power. If A+jB is the total impedance of the system, then A/(|A+B|) is the power factor. (Cosine component)
In other words it indicates that fraction of the total impedance of a system, which is dissipated as heat. And its this part of power which is measured in the meter at home.

Ideally if you reduce PF, your bill should come down. This basically means reduce the A componennt or increase the the B component of A+jB.

It also means, the load is more reactive (inductive/capacitve) in nature. This kind of loading can actually de-stabilize a power system as it translates to reactive current flowing back into power system. Its mainly because of this reason, electric companies define power factor to be high (active component) and and keep the reactive component to be low.


PS:Wow! When was the last time I read that? It just seems hazy now!

EDIT: I think the device is just adding up reactive load into the system and hence reducing the power factor. I just hope it maintains the limit.

[Samurai]

You mean they are reducing PF instead of improving it? Isn't that an illegal way of reducing the bill?

[mayuresh]

Originally Posted by Samurai

Did I say that? I only said it increases current drawn. If you look at the graph, the power consumption ratio refers to the PF value, the actual usage.

You didn't say that. I quoted that part where I differ precisely.

The common domestic meters at home, do they compensate for PF and read correct consumption?

I am absolutely sure they do. Even a domestic KWH meter is based on instrumentation that responds to power rather than current. They don't have to do something explicitly to "compensate" for power factor. Yes, they do have to do something explicit if they want to measure power factor, which more advanced meters do (and recent generations of domestic meters also do this).

Originally Posted by amitk26

So in absence of inductive load (only LED lights or electronic equipments) this should consume more power

The power consumption in the device is as per its power requirements - no matter the device is inductive or not.

However inductive devices draw more current to cater to the same amount of power requirement, thus increasing transmission losses.

Resistive loads have a near 1 power factor, thus they incur no transmission losses. Loads such as incandescent or LED lights should have near unity power factor. Loads that use adapters, would still have minor inductive load. But I don't think losses due to such devices are as much a concern as those that use motors (particularly if their makers haven't designed them properly to maximize power factor).

[ampere]

Got curious and looked at their site. The FAQ section particularly caught my attention.

http://energysaverindia.com/faq.html

1. Is the P.F.Corrector legal to use in India?
Yes, it is legal. Any changes to do before the Electricity meter reading are considered illegal. De Energia P.F.Correctors installed after the meter reading.

Now what does this "after the meter reading" mean? If you are correcting after the meter reading, how is your bill coming down? (The next billing cycle?)

And the other thing which caught attention was how they explain the working principle:

http://energysaverindia.com/working.html

Working Principle

The P.F.Corrector uses a combination of filtration and correction techniques to improve the efficiency of various appliances and circuits. In addition, the intelligent technology optimizes the voltage and current demands thus improving the Power Factor to reduce the wastage of energy.

The P.F.Corrector is a high efficiency device that optimizes the Voltage and Current (Static or dynamically) as the energy consumed increases in the approximately square of input voltage, hence the output energy would reach to an optimum level.

P.F.Correctors are what you call Synchronous condensers. Most motor loads in our house are Inductive loads, like pumps, fans, mixers etc. Even Air Conditioners and Refrigerators are inductive loads. The power factor of Inductive loads is lagging and synchronous condensers supply a reactive power factor and help nullify the effect.

So We See in Theory Synchronous Condensers do Correct Power

P.F.Corrector Uses State Of The Art Electrical Technology To Actively Monitor And Improve The Power Factor Of Your Household Appliances

Exactly as I mentioned in my previous post, looks like they do indeed add reactive load (a condenser), which should bring down the power factor.

[sudev]

Another aspect of capacitors usage in circuit is that it can only help in inductive loads. Motors, tube lights, etc.

I am not sure about CFL is there a built in capacitor? Or LED lights.

It does not help in heating loads like normal bulbs or heaters.

[amitk26]

Well Mayuresh I think you did not read what I posted.

If suppose load is purely resistive and you are adding an ultracapacitor it will actually slightly increase the power consumption.
Basically you do have a PF of 1 and by adding a capacitor you are lowering it.

Actually speaking if you attach a big capacitor all it will do is to charge up when line is connected and discharge and there will be some losses in the process.

Same thing can be understood in terms of power triangle as well which was stated in earlier post.

Originally Posted by mayuresh

The power consumption in the device is as per its power requirements - no matter the device is inductive or not.

However inductive devices draw more current to cater to the same amount of power requirement, thus increasing transmission losses.

Resistive loads have a near 1 power factor, thus they incur no transmission losses. Loads such as incandescent or LED lights should have near unity power factor. Loads that use adapters, would still have minor inductive load. But I don't think losses due to such devices are as much a concern as those that use motors (particularly if their makers haven't designed them properly to maximize power factor).

[Jeroen]

Interesting thread. Its been many years since I was involved in this sort of things. I used to be in the navy / off shore industry. Obviously, you produce your own electricty. On very old ships we had to manage the PF seperately, but I can only think of one ship I actually sailed on.

I'm not even sure if, for instance in Europe, Industrial companies have to manage this separately. My impression, but I could be wrong, is they dont'. The grid itself is very stable and maybe also the equipement in the industry might have to comply to different specifications to esnure a proper PF.

On this particular device that was shown at the beginning of the thread.
I assume its for consumer useage? And if, as I understand also in India consumers pay per KWH, I dont see how this device could reduce your electicity bill. At best this device reduces the current drawn.

30% savings? If you see something that seems to be to good to be true, it usually is. If you think what 30% savings means in terms of improving the PF, you would have to have a real awfull power supply to start with.

But maybe I'm wrong, bit rusty on this topic, but nice to read through it, slowly coming back to me

Jeroen

[mayuresh]

Originally Posted by amitk26

Well Mayuresh I think you did not read what I posted.
If suppose load is purely resistive and you are adding an ultracapacitor it will actually slightly increase the power consumption.

Yes, my mistake. I agree with the above.