How much KVA of power backup?

[anm]

Hi - I currently have only 2 KVA of power backup at my house - which means I can't run even a single AC.
The RWA has presented a golden chance of increasing the backup, given there are enough applications from everyone.
I am wondering how much total do I need based on following:

Higher side: Will total 5KVA suffice???
To run 3 ACs of 2 tonnes
Projector/ AVR/ AMP
some lights/ fans

medium side: 5 KVA??
2 ACs of 2 tonnes
Projector/ AVR/ AMP
some lights/ fans

Lowest: I guess 3KVA total should do.
1 AC, 3 lights and 3 fans

 

[sridhar-v]

Hi - I currently have only 2 KVA of power backup at my house - which means I can't run even a single AC.
The RWA has presented a golden chance of increasing the backup, given there are enough applications from everyone.
I am wondering how much total do I need based on following:

Higher side: Will total 5KVA suffice???
To run 3 ACs of 2 tonnes
Projector/ AVR/ AMP
some lights/ fans

medium side: 5 KVA??
2 ACs of 2 tonnes
Projector/ AVR/ AMP
some lights/ fans

Lowest: I guess 3KVA total should do.
1 AC, 3 lights and 3 fans

3 a/c's of 2T rating each - you will need a 20KVA genset to take care of the starting current inrush. And if you even manage this in a UPS the battery bank will be huge.
As a guideline for a 0.75 T a/c SUKAM is recommending 2.5KVA ups with 4 batteries of 200AH. Als if you run this for 5 hours then you need 20hrs to recharger the batteries. Otherwise using higher current charging will quickly ruin your battery life.

 

[anm]

sorry - I am getting this power backup from a central power backup of the colony. So no individual genset or battery.
I am assuming that the large gensets of colony's backup should be able to handle the initial current requirements.

 

[anm]

Any inputs? today is the last day for applying for the same

 

[amol12]

Central power backup is usually based on generator although recently I have also seen inverter/battery based ones for common areas.
I dont have any expertise in this area but mathematically if on 2KVA you cant run even a single AC, on 5KVA you I doubt you would be able to run all 3 (or may be even 2).
Going by the 20KVA figure by sridhar-v, you should ask for maximum possible if not 20KVA.

 

[borg]

yes, consider 4kva per 2tonne ac,if all are 5 star rated you could consider 3kva/ac
2-3 kva for all other stuff(pj,avr/light/fan)

 

[anm]

It seems for 2 AC + avr etc it would be 10KVA. hmm - it is quite expensive - have to pay 25k per kva.

I can at max go for 4 kva extra which comes to 1 lakh and a total of 6 kva backup. Seems I will be able to run just one AC with 6kva.

 

[rbalagopalan]

Hi ANM,

Let me share what i know here. 1 KVA multiplied by the power factor of 0.8 gives you 800watts of power. I think now it is straight forward for you to calculate the watts or Kilo watts of your total connected load and decide on how much KVA of power ups you require.

This is not as easy as it sounds cause A/Cs method of starting is DOL starters (Direct On Line) in which case the starting current is going to be almost 6 times of the running current. Hence you may have to take this in to consideration in which case you have to over size the UPS accordingly.

Leave alone the Total connected load now you have to worry about the duration of the backup time you require which will decide your battery bank keeping all the above in mind I think It would not be viable to prefer a UPS for such loads for domestic application.

With regard to the starting current of A/Cs there is one more solution available, now a days top brand A/C cos have come up with Inverter grade (Variable frequency drive) A/Cs in which case the starting current is on par with the running current (In fact you can plug in a 1 tonner in your normal 5 amps domestic outlet) and you will have phenominal power saving of as much as 40%. Of course this calls for a huge investment.

It is better and economical to go in for super silent gensets with auto start and stop which can give you true uninterupted back up.

Thanks

Balagopalan

 

[cmsajith]

consider a solar/wind energy route (may be DIY). Initial cost will be high but in long run you will get free electricity.

 

[avidyarthy]

^^^^^^^^^

 

[anm]

I AM NOT BUYING A UPS OR GENSET OR A WINDMILL.

There is a common power backup of the society - I need to buy X KVA load from the common pool

sorry - I am getting this power backup from a central power backup of the colony. So no individual genset or battery.
I am assuming that the large gensets of colony's backup should be able to handle the initial current requirements.

 

[anm]

ok - just called a guy in my neighborhood and he suggested to go for 5kva for 2 ACs. He is having trouble running third. So I am going for total of 6KVA.

 

[avidyarthy]

... hehe .... for a middle class residence ... sorry, upper middle class (3 ACs .. ), a 5 kva load is more than sufficient. It would easily run a SINGLE 2 TR AC .... some lights and fans.

Do not try run the other ACs. Also suggest NOT to connect your HT to this supply .... a strong surge comes in during the gen-set kick-in stages.

 

[anm]

yep - have downgraded my requirement to 2 ACs instead of three.

 

[cmsajith]

I AM NOT BUYING A UPS OR GENSET OR A WINDMILL.

There is a common power backup of the society - I need to buy X KVA load from the common pool

Hmm... didnt go through your thread properly. In our apartment complex we have 3 gensets. We are thinking about the feaibility of free electricity either by solar/wind mills by utilising the roof area of all apartments. Just commented about its possibility thinking that the requirement is for an individual house w/o backup facility.

 

[anm]

for solar/ wind etc - huge batteries would be needed. Will explore the possibilities for the entire society, in another thread

 

[prankey]

consider a solar/wind energy route (may be DIY). Initial cost will be high but in long run you will get free electricity.

Solar panels are actually a good suggestion for an apartment complex atleast for backup of common area.

anm - 5kVA should be good for 2 ACs load and you CAN run almost the entire household including PC/AVR/Plasma TV, Laptops, etc. with 1 AC! Just get a good surge suppressor (I suggest Belkin with Insurance option) for your TV/AVR/PC, etc.

 

[anm]

I just checked my electricity bill. It says connected load - 16KW, chargeable load 5.11 KW
Watt does it mean! Not sure if the connected one is avg for last month, or max ever, or just some random sample.

 

[oyeindia]

I just checked my electricity bill. It says connected load - 16KW, chargeable load 5.11 KW
Watt does it mean! Not sure if the connected one is avg for last month, or max ever, or just some random sample.

The connected load is the maximum possible load allowed for your home circuit. That's what the electricity company has provisioned for your house. You could possibly draw more than that, but they'll penalize you for over-drawing.

"Chargeable load" - I'm not sure of this. I would assume it's something to do with the billing category for your connection, for the flat rate that's charged per month.

 

[anm]

I just realized I live in a socialist society (it even rhymes) - they have capped max to 5KVA. Ridiculous I say, because on one hand they are collecting funds to buy new gensets and otoh they want to first give it to as many houses, then give it to people like me who have no ethics but just want to throw money. How can I even think of running 2 ACs of 2 tonnes! When some of my bros would be sitting in the dark. And those bros have been asked 7 times to get a power backup but they don't want to pay.

I was even asked my occupation. I think the old retired guys were really mad at me and they went totally mad on hearing "software".