Electricity bill Saving by using Capacitor banks

Capacitor banks are an integral part of every industry as it is required for compensating reactive component of inductive load. Capacitor banks are required to save electricity bill as in inductive load power factor is lagging and more lagging is the power factor more will be your electricity bill.

In simple terms if you check your electricity bill and it shows power factor of 0.8 than you will be paying 20% more electricity bill which is huge amount considering the load required by your organization. So there is requirement of capacitor banks which will make power factor more closer to 1. You can't be able to make to 1 but more closer you will be to 1 more savings will in your electricity bill. You can make closer to around 0.98-0.99 power factor. 

if you don't know about power factor you must approach an engineer for the same. They will guide exact about the capacitor bank requirement for your organization. 

Further investments are not huge for capacitor banks. You have to pay around 500-600 Rs. per KVAr including panel. This cost will be recovered by your company within 1-3 months depending upon power usage of your company.

Depending upon the states your capacitor requirement has to be taken care. e.g. In Delhi there are power suppliers are NDPL, BRPL, BYPL and NDMC in NDPL, BRPL and BYPL areas you can even overcompensate the  required capacitor bank, this means that you can install capacitor banks more than you required. But in Haryana State and UP states you can't overcompensate the capacitor bank requirement as this will also leads to charging of more electricity bills.

In Haryana and UP states you have to install the automatic power factor controllers for achieving the required compensation as in these states installed meters are four quadrant meters which will work on over compensation, means meters will read over compensation as load and keep running even when there is no load running at the times. 

So in Delhi you can install the capacitor banks without APFC panels and in Haryana and UP you have to install the APFC panels.

So whenever you are going to apply for new connection in a state, first check for type of meters they are going to install and accordingly you can plan your capacitor bank requirements. 

Note:- If you can't be able to check power factor in your meter than you can even check the same on the electricity bill and if you are adding new motors or lights into your system than check for power factor of lights and motors which you are going to get installed into your system. This will help you earlier planning.

Further you are also suggested to switch off the power factor panel when not in use as this save some of electricity bill as there are some losses in power factor panels when they are not in use.

Maintenance:- You have to do the maintenance of power factor panels also so as to check for healthiness of power factor panels. Your electrician have to simply note down the current drawn by every capacitor banks and if any capacitor bank is withdrawing lower current than simply replace that capacitor bank and maintain the panel in healthy condition.

Tips for engineer and electricians;- 

(i) Capacitor banks requirement formula which isn't available in text books:- If you not sure about the which rating of capacitor banks required for your system, than just simply insert the tongue tester (For current checking)  into the main line and keep it on and keep on switching ON the capacitor banks one by one or add the capacitor banks one by one. You will find out that current will start decreasing on main line as soon as capacitor banks kept on increasing but at a certain stage current will start increasing in main line than you have to switch off that particular capacitor bank as this is maximum capacitor bank requirement for your system.

(ii) Mistake made mostly while installation of APFC Panels:- Whenever you are going to install the APFC panel into your system that CT(Current Transformer) of the APFC panel must be installed into the main line. As APFC panels works on the current withdrawn by the load connected to the system. There is general mistake made while connecting the APFC panels is that panel builders take the input for APFC panel relay(which operates the capacitor banks) from the input of APFC panel. This will defeat the purpose of APFC panels installation and APFC panel will not work as required.

(iii) Repairing of Capacitor Banks:- You can't repair the capacitor banks, simply replace them whenever they got faulty and faulty capacitor banks even explode if you try to reuse the same after some repair works. 

(iv) Always use well repute make of capacitor banks. Never ever use the local capacitor banks.

Below is the power factor calculations for your system:-

Capacitor banks are used for compensating reactive load connected at load end. It is usual practice to keep KWH consumption = KVA consumption
KWH consumption= Voltage X Current X power factorX time
KVAH consumption= Voltage X current X time

Now Power factor= KWH/ KVAH

Now if power factor is low then there will be higher KVAH consumption as KWH is constant. So lower power factor leads to higher current as voltage of system is constant. This will leads to higher KVAH than KWH and leads to higher billing in case of lower factor.

Capacitor banks are most widely in industries to save electricity bill as in industries billing is done in KVAh.  KVAH can become equal to KWAH when unity P.F. Is achieved as most industrial motors and lighting load having p.f. ranging from 0.7- 0.8 which causes KVAH to be very high in comparison to KWh.

This lower factor is due to reactive component of power in order to compensate this reactive component of power capacitor bank is used in parallel with load. When there is power factor is as low as 0.8 then there will be higher billing of 20% as power factor is lower by 20%. So you can figure out how much capacitor bank will save.

One Most Important thing here is that Capacitor Banks are useful for only Industrial applications but can't be useful where metering is done in KWH as KWH can't be reduced using capacitor banks. 

Power savers for Domestic applications:-

Most of persons fall in the trap that equipment is available in the market known as power saver is used to reduce electricity bill. But that Power saver consists of nothing but capacitor banks which doesn't reduce electricity bill instead increases by some amount as there are power losses in Capacitor Banks. So don't go to buy power saver at all. 

Overcompensation factor

Most of persons think that if more capacitor banks are installed then there will be more power saving but technically we can't increase P.F. beyond 1. In order to keep power factor 1 all times even industries overcompensate the system by installing more capacitor bank then requirement. This is will only leads to more current on cable as capacitor bank after compensating reactive power will leads to only excessive current on cable and which leads to heating and losses across cable. Some power co.s even give rebate on electricity bill to industrial consumer it they maintain P.F. above 0.95.

Thus we see that there are both advantages and disadvantages of capacitor banks, but advantages are more than disadvantages.

Below is table for calculations of Capacitor bank requirement depending upon the system power factor.

In above if there is 160 KW load connected and having power factor of 0.8 and needed to be increased to 0.98 then Capacitor bank requirement will be= 0.547X160= 87.52 KVAR