Electricity Saving Tips For Homes And Offices

Power Saver Devices or Capacitor Banks – do they really save electricity?

By on April 22, 2016

Several times we come across devices that are sold and branded as power savers and claim to reduce significant amount in electricity bills. The questions that come in our minds at this stage is: Does it really save electricity? Is it legal? Can it work for my home or office or factory? The answers to these questions are very simple: Does it save electricity? Yes but only in certain cases. Is it legal? Absolutely. Can it work for my home or office or factory? Again only in certain cases.

So what is a Power Saver Device?

As we discussed in our previous post on Power Factor, there are 2 kinds of electricity loads: resistive (e.g. lights, water heaters, coil heaters, etc) and inductive loads (e.g. ceiling fans, pumps, air conditioners and refrigerators). For resistive load, the energy (or electricity) supplied by utility is mostly same as the electricity used by the appliance. But in case of inductive loads some energy is used up to create magnetic field that is not useful. And the formula for the same is:

kVAh (energy supplied by utility) x  P.F (Power Factor) = kWh (energy used by appliance)

A power saver device improves the power factor that results in lesser kVAh (energy supplied by utility) per kWh (energy used by appliance). It does so by reducing the electrical current drawn from the utility.

What are Capacitor Banks?

Power saver devices are nothing but capacitor banks. Capacitor banks provide capacitive load which is opposite of inductive load. When put in parallel with inductive load (like ceiling fans, pumps, ACs, etc) they improve the power factor thus taking less energy (from utility) for the same appliance (or same amount of work). Capacitive load in parallel with inductive load makes the system resistive.

Where do these devices help?

These devices are good in following situations:

  1. When there is lot of inductive load in the system (lots of pumping, air conditioning, refrigeration and fans) and the utility bills in kVAh.
  2. When the wiring is not good and lots of electricity is being lost as heat through the wiring. Lesser current because of power savers can help reduce heat loss through wiring.

Can it help at your home?

Typical residential (even for housing societies) billing happens in kWh (energy used by appliances) and thus there is no apparent benefit of power factor correction. Unless wiring in your house is too bad, you will not observe much saving by using a power saver device. Power saver may reduce the heat losses in wiring, but that will not be significant enough to justify the investment.

Can it help in your office or factory?

In some commercial and most industrial sectors billing happens in 2 ways:

  1. The contracted load is in kVA (or demand based billing).
  2. The billing happens in kVAh units.
  3. There are power factor penalties/rebates.

If billing is in kVAh, then by using power saver devices the kVAh consumption is less and the number of units that show up on electricity bill will be less.

If billing is in kVA (or demand based billing), you will reduce your maximum demand by putting power saver devices and thus save on fixed costs.

If there are power factor penalties then you save by improving the power factor of your premise and in fact can gain with better power factor rebates.

In case none of the above 3 conditions apply in your case, and then you will not save much by using a power saver device.

References:

http://www.energymanagertraining.com/announcements/EE08_result/SanjivArora(A).pdf

http://en.wikipedia.org/wiki/Power_factor

http://www.engr.colostate.edu/ece-sr-design/AY06_07/power_factor/PFC.pdf

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27 comments

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1

do you have T5 54w HO r fluorescent tube light?

2

Are whole house voltage protectors useful or not? I am thinking of installing one of the following equipment

http://www.accurexpower.com/home-protector.html

3
Abhishek Jain (Mod)

They will have their own electricity consumption which would be roughly 2-3% of your total electricity. So your electricity bills will go up by 2-3%. Go for it if you have voltage fluctuations throughout the year. Else if it is only in summers then for the rest of the year you will consume electricity when it is not needed.

4

Sir, i want power saver for 100kva commercial LT unit. Kindly suggest and power saver cost also

5

hi , you say these devices are legal , such as energy saving cards, which are stuck, having negative ions etc. will it not amount to theft of electricity, as they work similar to a capicator but are not connected on line, like other devices.Please guide .
thanks Sanjay

6
Abhishek Jain (Mod)

Capacitor banks improve power factor on the line which improves the efficiency of power supply. In fact, your power distribution company will encourage you to put capacitor bank if you do so. They give rebates to commercial setups that use capacitor bank for power factor correction. And it not only saves electricity, it makes the whole system better and more efficient. It is just that the billing in residential setup is on kWh instead of kVAh that these devices do not provide any real savings. But even if you put it in residential setup, your electricity distribution company will certainly like it. And it is not same as theft. Not at all.

7

Power sever ko kase use kia jata hai agar ye lagana aasan hai to main b lagana chahata hu apne ghar me mere ghar me 2.k.w ka meter hai jaha sirf 2 fan or do tube lite hai . 1ref 1 cooler or ek t.v chalta hai or month me bill 1500 and above he ata hai

8

Hello Bijli Bachao team. I purchased "Maxx Enviropure" power saver on Ebay and i received it within 3 days. But to my utter surprise, when i tested it then i found that every time i uses it, it makes at least 2 or 3 units (per day) more than the day when i am not using it. I know, it may look like a joke but its true. I have tested it for 5 days. please guide.

Thanks.

9
Abhishek Jain (Mod)

Hi Rockie,

As we have written on the writeup above, power savers DO NOT work in residential connection. These capacitor banks work good to improve power factor which is good in a commercial connection where billing happens in KVA. In a house, the billing happens in KW and it will not work to save electricity.

10

Thanks for the prompt response, Sir. I feel cheated by these guys as they didn't mention this thing in their promotion.

Wouldn't be using this. Thank you.

11

Well I just wanted to have an exact and brief definition of power saver devices along with some examples and uses....so can you please provide some??

12

It's true that we can use a capacitor bank to supply the reactive power to a reactive load and stop the voltage from dipping . so can we use a capacitor bank along with a Ac to maintain the overall house vol.

13
Abhishek Jain (Mod)

Hi Avik,

When you start the AC it needs more inductive current and I doubt that a capacitor bank will be able to support that. It may have marginal effect but if the drop is big (more than 20V or so) then it may not help at all. If voltage is dropping at start then most probably the wiring is faulty. It will be better to have a look at the wiring.

14

Thank you for your all Articles on Power Factors and Capacitor Banks. I found them very very informative. Have you tested any specific Power/Capacitor Banks that would work great with saving electricity used by AC Units and large Fridges? Please recommend to me at least 2 good ones you have found. Very much appreciated.

15
Abhishek Jain (Mod)

Hi Gordon,

We have not tested any specific capacitor banks. So cannot comment much on this.

16

Thank you. If you were to try a few, which ones would you try? I am trying to select a few, so I can do a comparison. Thanks.

17
Abhishek Jain (Mod)

You can check with Havells or Schenider electric.

18

Thank you for your help. Will try them.

19

Robo
These devises actually save you electricity if it is sized properly. That is the key. Most sold and installed are a one size fits all and won't work with small electric bills. Some smaller units can be found and installed directly to the a/c unit.

20

Dear Abhishek

I live in flat(First Floor) in a thee story house.

One electric meter(main) insttled in ground Floor and Two sub-meter insttled First Floor and Second Floor.

House onwer received electric bill from me on basis of sub-meter shown reading. and also second floor.

But problem is mentioned below:

Electric bill (main meter) come from electricity department is low compare to my bill+ second floor bill (sub-meter).

Whereas main meter show three story used electricity.

We also replace sub-meter but problem is same.

So, my question is any solution for this problem ?

Or Power Saver Device is solution ?

Pl. help me.

PRAKASH

21
Abhishek Jain (Mod)

Hello Mr Prakash,

Typically electricity company will provide only one meter per address. Now your owner may have installed submeters on his own on 1st and 2nd floor and he may be charging you on the basis of the reading on the submeter on your floor. Now the question to you is 1) Do you get bill from the electricity company or do you get it from owner? 2) What rate are you paying per unit for the electricity? 3) Which state/city are you in?

22

owner have installed submeters.

Answer of your Question:

(1) Owner

(2) Rs. 5/- per unit

(3) Chandigarh

23
Abhishek Jain (Mod)

Hello Mr Prakash,

Rs 5 per unit is a bit on a higher side in Chandigarh. The tariffs are as follows:

First 150 units at Rs 2.3
Next 250 units at Rs 4.2
All the units after that at Rs 4.4

Now including FAC and fixed charges the last slab may be close to Rs 5 per unit. But this calculation will happen at the main meter level and not at the submeter. And if the combined meter reading for all the three floors is exceeding 400 units then all the last units are at close to Rs 5 a unit. So essentially you are being charged at the highest tariff always.

24

My problem is meter reading not amount like total reading is 396 unit (main meter) in a month wheras my reading is 200 unit (only first floor) and second floor is 175 unit. Rest unit (21) consumed by Ground floor, but practically not possible bacause home appliance almost same all three floor. We also replace sub-meter but problem is same.

My question is Power Saver Device is solution ?

25
Abhishek Jain (Mod)

Hello Mr Prakash,

There is no power saver device that works in residential connection unless you are installing the power saver for ACs. Looking at your problem statement it looks like the efficiency and speed of the main meter and sub meters does not match. Is the main meter old electro magnetic meter with a rotating disc? If so then it is highly likely that it may be running slow.

26

can i have a schem diagram for this application sir/mam because im still a student of (M.U.S.T.)and requirable for my project .please me for need help.,.thnx .just pm me 4 my email add fb.

27
Abhishek Jain (Mod)

Hi Robin,

Sorry, we do not have a scheme diagram for this. You may search more on internet and may find it somewhere.

Regards,
Abhishek

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