[hellmet]

Originally Posted by Thad E Ginathom

If maximising the battery-backup duration is the priority, then consider that, when not doing reading, sewing, etc, all that is necessary is to be able to see one's way around the room! Even with a genset, this will save you fuel.

We don't do a lot of reading in the house and not esp. during a power cut so we can definitely cut down on the lighting. However, I still would like to have one 40W tube light for the kitchen for safety purposes.

Originally Posted by joybhowmik

I am assuming a scenario of Power Factor = 0.5 - this is not unreasonable considering the range of devices in your list.
Having said that your VA requirement = 1384/0.5 = 2768.

While you can go in for buying a larger capacity inverter and more batteries, it is definitely easier to re-consider if you really need all the devices to have full power backup at all times.

Thank you, I'd never have figured out the PF myself (always had a hard time with E&E)
What I really want to achieve is minimal loss of convenience during a power cut so life can continue as normal instead of having the crippling feeling of loss of electricity.

Originally Posted by joybhowmik

It may be easier and cheaper to do the following:
Start by making a list of devices satisfying the following criteria:
List 1: Device needs to be working 24X7
List 2: Device is likely to be used only intermittently- maybe half-hour to an hour at most.
List 3: Device is likely to be used only during the night.

A) After enlisting , work out the base VA requirement that your UPS should support (viz List 1).
B) Next find out the maximum VA requirement of List 2 and List 3, and add that max. VA requirement to the base VA requirement
Add A to B , and - that's the capacity of the inverter you 'should' buy.

I definitely will work on creating separate lists. Ideally, though, they should all work if and when necessary.

Originally Posted by joybhowmik

Next , you should also run a separate power line from UPS output to the devices in List 1, and make a provision to power on devices in Lists 2 & 3 (e.g. an extension board connected to the UPS output).

This will ensure that your UPS+battery is never bearing an unreasonable load.

Can you please explain the difference between a UPS and an Inverter+Battery combination?

Any ideas for the generator?

[joybhowmik]

Originally Posted by hellmet

Can you please explain the difference between a UPS and an Inverter+Battery combination?

Both inverter and UPS depend on batteries for storing power when mains is on, and discharge the battery when mains is off.

A normal inverter only converts DC from the batteries to AC. It has a relay that detects mains voltage presence (either on or off) - and when the mains goes off, the inverter starts feeding the circuit. Hence, there is a delay, between the mains power going off and the inverter kicking in. There is usually also no protection against spikes in the mains.
If you are running devices such as desktop computers, hard disks etc. on an inverter, sudden power fluctuations can lead to catastrophic failures. So people who have inverters, therefore supplement this by buying a small capacity UPS (300~500 VA) for their expensive desktop, external hdds.

UPS = Normal Inverter + Magic Box of power electronics.
UPS - Uninterrupted power supply - nowadays the technology exists to bring you near sinusoid AC , which kicks in within a few micro-seconds of the power going off, and most importantly constantly keeps the output voltage at the standard 240 V, ~50 Hz despite fluctuations at the mains due to your utility's deficient services.
Not only that, the UPS also automatically stops charging the batteries when fully charged- thereby extending battery life. It does all this with a 'magic box' of pretty complicated power electronics.

Now one has a choice of buying either an inverter or a UPS. But do consider the point that, the newer UPS technology is now mainstream with all market leaders -e.g. Sukam, Luminous etc. Therefore, buying into the older inverter technology will also mean dependence on local service providers & manufactured components - who may not have the kind of quality processes, warranty services , customer care network that market leaders have. Also consider the flexibility the UPS gives you over an Inverter. For the same rating, an UPS will likely be about 50%-60% more money - that's why I went for the UPS, even though it is more expensive.

[pganapathy]

Originally Posted by hellmet

4CFL bulbs X 22 W = 88W (bedrooms+living)
3CFL bulbs X 11W = 33W (bath)
2Tubes X 40W = 80W (kitchen+dining)
4Fans X 60W (they're rated 100W but who runs them at full speed?) = 240W
Two plug points for various devices (laptops/cellphones chargers) X 50W = 100W
1 Mixer-Grinder = 500W (had no idea it was such a power hungry item)
Refrigerator rated as 180W defrost, 160 W input, 0.7A. No idea what this means = 180W
1CRT TV X 83W = 83W
DTH STB = 30W
1 Wireless Router + 1 Modem = ??W (counting another 50W) = 50W

Total: 1,384 W

Now the refrigerator is not a must, but I don't really know the implications of having 6 hour power cuts on an appliance like this. I hope it doesn't die trying to cool itself after an elongated cut.

I'm looking to run this configuration entirely on battery+inverter technology with an option for it to recharge via Mains, Genset, or other intermittent supplies such as Solar or Wind, in that order of preference. My goal is to be able to survive grid break downs (of 2-3 days) such as those seen in North India, because with such acute power shortages in AP, it is bound to happen sooner or later.

I'm guessing a Petrol Genset would be a good idea since Kerosene is not freely available and gas stations would run out of diesel first due to heavy genset and public transport demand. I also want one that is as silent as possible to keep ourselves sane in the house, so I can only think of petrol.

Remember that this genset would only run after the inverter starts to run out of juice and not everytime we have a power cut. So, both devices must be able to handle the load mentioned above individually. Can gensets start on their own detecting a load?

What do you guys suggest we go for based on these (horribly long list of) requirements?

The bulbs, tv, fans, computer etc are not too much of a problem. Even an 800 vA inverter would run that. The fridge and the grinder are the problem.

We use a 1.2 kvA in our estate in Coorg and it even runs one fridge (we have two and if the cut is long we alternate them on and off). I would suggest the 4 or 5 star energy efficiency rating ones. The point here is keeping a fridge running does not require a lot of electricity. It is starting it that is energy heavy. Thus a 1.2 should do the job for all that. Now comes the biggest problem. The grinder. Our 1.2 cannot handle a washing machine, iron box, geyser, chapati maker or microwave. I would assume the grinder is the same. If memory serves me right, the discussion with my inverter guy came to the conclusion that we would need a 2 kvA inverter for this. This is of course more expensive.

Duration of the inverter is dependent on the number of batteries connected. A 2 kvA with four or even six batteries should easily last you three to four days, and possibly even a week with judicious use, so I would suggest not bothering with the generator. Additionally, if space and money permit, you can even hook up a solar panel or two and have them charge the batteries.

Yes, this will cost 50,000 or possibly even more, but it is a one time investment, except the batteries which would need to be replaced every couple of years.

My suggestion is get a 1.5 to 2 kvA inverter and start off with two batteries. If you find the life to be short, get another two batteries. If that is still short 2 more batteries or the solar panels for charging the batteries.

Feel free to PM me if you would like more details WRT cost, make etc. I can ask my dad and get back to you

[hellmet]

Originally Posted by joybhowmik

UPS = Normal Inverter + Magic Box of power electronics.
UPS - Uninterrupted power supply - nowadays the technology exists to bring you near sinusoid AC , which kicks in within a few micro-seconds of the power going off, and most importantly constantly keeps the output voltage at the standard 240 V, ~50 Hz despite fluctuations at the mains due to your utility's deficient services.
Not only that, the UPS also automatically stops charging the batteries when fully charged- thereby extending battery life. It does all this with a 'magic box' of pretty complicated power electronics.

Now one has a choice of buying either an inverter or a UPS. But do consider the point that, the newer UPS technology is now mainstream with all market leaders -e.g. Sukam, Luminous etc. Therefore, buying into the older inverter technology will also mean dependence on local service providers & manufactured components - who may not have the kind of quality processes, warranty services , customer care network that market leaders have. Also consider the flexibility the UPS gives you over an Inverter. For the same rating, an UPS will likely be about 50%-60% more money - that's why I went for the UPS, even though it is more expensive.

Thank you SO much for the explanation Joy! From this I understand that newer technology is UPS based and if I do go ahead with a power backup plan, I should go with a UPS solution instead of an inverter solution.

Originally Posted by pganapathy

The bulbs, tv, fans, computer etc are not too much of a problem. Even an 800 vA inverter would run that. The fridge and the grinder are the problem.

Well, if it really comes to the grinder, we might very well sacrifice the convenience if it turns this project very expensive.

Originally Posted by pganapathy

Duration of the inverter is dependent on the number of batteries connected. A 2 kvA with four or even six batteries should easily last you three to four days, and possibly even a week with judicious use, so I would suggest not bothering with the generator. Additionally, if space and money permit, you can even hook up a solar panel or two and have them charge the batteries.

I stay in an apartment, so having solar panels on the common roof top may not be possible and also having kids playing around the panels would freak me out. I might look into a wind turbine, if installation is possible without digging foundations.

Originally Posted by pganapathy

Yes, this will cost 50,000 or possibly even more, but it is a one time investment, except the batteries which would need to be replaced every couple of years.

Do you mean just the 2KVA inverter and batteries would cost Rs50,000 ? Or did you also include the solar panels pricing ?

Originally Posted by pganapathy

Feel free to PM me if you would like more details WRT cost, make etc. I can ask my dad and get back to you

I truly appreciate that! Thanks a lot. You may find a PM or two in your inbox in the coming days.

[pganapathy]

Originally Posted by hellmet

Thank you SO much for the explanation Joy! From this I understand that newer technology is UPS based and if I do go ahead with a power backup plan, I should go with a UPS solution instead of an inverter solution.


Well, if it really comes to the grinder, we might very well sacrifice the convenience if it turns this project very expensive.

I stay in an apartment, so having solar panels on the common roof top may not be possible and also having kids playing around the panels would freak me out. I might look into a wind turbine, if installation is possible without digging foundations.

Do you mean just the 2KVA inverter and batteries would cost Rs50,000 ? Or did you also include the solar panels pricing ?

I truly appreciate that! Thanks a lot. You may find a PM or two in your inbox in the coming days.

Look forward to answering what I can with regards to the inverter questions.

Some quick points that I do remember. An 800 vA will cost 15 to 20k with one battery included. Each additional battery (if the load is enough but you want extended lighting time) should be around 8 to 10k. There are bigger batteries which cost 12 to 15k if memory serves me correctly.

Our 1.2 kvA came to around 35, IIRC, which comes with 2 batteries. The 2kvA costs around 50k IIRC. It comes with two batteries.

If you have one of those modern fridges and it is a four or five star energy rating, you should be able to get away with a 1.2 kvA, barring heavy duty items like the grinder, iron box etc.

Solar panels are not cheap yet. They should be subsidized to encourage it's use, but the government hasn't done that yet, for reasons best known to them. Will need to check latest rates, but a small panel was 10 to 15k. Is a worthwhile investment long term if you can use it to reduce your electricity bill.

The reason I say don't bother with a generator is that you live in Hyderabad. In any of the metros or big cities in India, the rule tends to be you cannot go more than 6-8 hours at the very most without electricity, barring an emergency. So a generator will seldom be used, and is a waste of money for me. In the more rural areas, we consider ourselves lucky if we get 6-8 hours of electricity in a day, especially during the periods when there is a shortage. Additionally during the monsoons we have a lot of lines coming down with trees or branches falling on them. It takes a while to get repaired in rural areas as opposed to urban areas.

A small solar panel can even be put in your balcony if there is a lot of direct sunlight there.

[hellmet]

I'm seriously missing the "Thanks" button in this sub-forum.

@pganapathy, I will go ahead and call Su-Kam and Luminous in the next few days and see what they have to offer. And based on Joy's suggestion, I plan to go for a UPS solution unless it isn't too expensive, otherwise it'll be inverter plus separate small UPS for the modem/router.

[JMaruru]

Originally Posted by hellmet

otherwise it'll be inverter plus separate small UPS for the modem/router.

We have this little switch at the back of our su-kam inverter, where one can choose 'Inverter' or 'UPS' mode. I have it on 'UPS' mode and have not faced any issues with laptop/modem/router or our plasma tv, when the switch over to inverter happens. AFAIK, if you buy a decent brand of inverter it can be made to work as UPS.

[Prowler]

Originally Posted by JMaruru

We have this little switch at the back of our su-kam inverter, where one can choose 'Inverter' or 'UPS' mode. I have it on 'UPS' mode and have not faced any issues with laptop/modem/router or our plasma tv, when the switch over to inverter happens.

Originally Posted by hellmet

And based on Joy's suggestion, I plan to go for a UPS solution unless it isn't too expensive, otherwise it'll be inverter plus separate small UPS for the modem/router.

The switch on the back of Sukam inverter to select UPS or inverter mode is actually the switch which sets the range of voltage it will allow to "pass-through" before it decides to switch into the inverter. In other words, in the so called inverter mode - it will remain in Mains mode for 160-250 V while in the UPS mode - it will remain in Mains only for voltage 200-240. When the mains volt goes above/below the set value, the inverter kicks in and supplies power. (I have a Sukam Shiny Inverter and the above values are quoted from its booklet).

The change-over time is critical for sensitive appliances like Computers. That is the reason for servers and other mission critical computers you use a true UPS which supplies power all the time from the battery while it charges the battery in a separate circuit.
To run a laptop, routers and modems - you don't need another line-interactive UPS. Laptops have their own batteries and they won't bat an eye if there is a momentary power loss. The routers and modems are tolerant of momentary power loss.

[S_U_N]

What is the best price for Sukam Inverter Shiny 850 VA?
I have a local brand 150AH battery. Will it support?

One dealer offered it for around Rs. 5000, but he does not recommend Sukam - instead recommends Microtek since they are MOSFET based and not IC based. As per him, Microtek is repairable and Sukam is use-and-throw.
This is more relevant after warranty is over.

I am not happy with Microtek UPSE2 875VA for Rs. 6000 since it has trapezoidal waveform and that results in noise on fan and tubelights.

[JMaruru]

Originally Posted by Prowler

Laptops have their own batteries and they won't bat an eye if there is a momentary power loss. The routers and modems are tolerant of momentary power loss.

At home, i use one of my old laptop as desktop. The laptop battery is dead and it is always connected to the load. So far, I have not experienced any shutdown when the power switches to inverter. It is the same with modem/router.

[Prowler]

Originally Posted by S_U_N

What is the best price for Sukam Inverter Shiny 850 VA?
I have a local brand 150AH battery. Will it support?

One dealer offered it for around Rs. 5000, but he does not recommend Sukam - instead recommends Microtek since they are MOSFET based and not IC based. As per him, Microtek is repairable and Sukam is use-and-throw.
This is more relevant after warranty is over.

Sukam Shiny Inverter in Chennai costs around Rs.7000 (at least at the time I bought 2 weeks ago.) All inverters use ICs for signal processing and power transistors at the final stage driving the transformer. The output power transistors these days are MOSFET /IGFET. So you can replace them whichever brand you opt for. The dealer probably gets more commission from Microtek.

Originally Posted by JMaruru

At home, i use one of my old laptop as desktop. The laptop battery is dead and it is always connected to the load. So far, I have not experienced any shutdown when the power switches to inverter. It is the same with modem/router.

Yes. Sukam shiny inverter has a 'fast' change over time. But as long as they use a relay to make the change-over, there will be a finite delay which may cause a reboot with some computer's SMPS power supply - especially as the eletrolytics age or when the computer sits in hotter environment.

[oldmobile]

Originally Posted by diyguy

I have just enquired from my dealer and got a quote for Rs 6500 for 850va APC and Rs 13500 for Exide tubular. PM me if you want the number and I think we can get a few 100s off if more than one of you want it. I had got the same setup last year for Rs 18000 all inclusive but still feel the new rate is competitive.

Can anyone recommend reputable APC dealers in Bangalore. I want to get APC 850va and Exide Tubular 150AH.

Thanks

[drsingh]

Can anyone give me an estimate of the cost of installing a silent generator of 10kw capacity . The likes of mahindra/Sudhir/Jakson/kirloskar installed by small hospitals and banks.

I want to compare the cost with a conventional genset with auto starter. I was quoted about 1 lakh for the same.

[Aroy]

As far as I know, the base generator is 14KVA engine with a suitable alternator. The price of these with AMF panel and acoustic enclosure is upwards of 2.5L, so I doubt you will get any thing for 1L. The main cost of low power generators is the AMF panel followed by the enclosure and the alternator. The costs are between 2.5L and 5L for the range of 14KVA to 60KVA, with the AMF and enclosure contributing 1L.

When choosing a generator keep the following in mind
. The diesel consumption at 100%, 75% and 50% load
. The oil change interval in hours
. The minor and major service intervals and costs in hours

If the generator is to be used intermittently (as during power cuts), what is the start up and stopping times (as well as fuel consumption) during short runs

Once you get the relevant figures, you will be able to get the whole life costs which may be lower for a higher capital cost item. Please note that an inexpnsive generator may "drink" fuel and require frequent oil change/maintenance compared to a sturdier and costlier set.

[nevertouchme]

I have Both.

Yes, I have both; this part of TN where I live, uninterrupted power is plagued. There are times; the battery drains out and the inverter fails to charge the battery.

I've an APC 850va Pure Sinewave and Exide Tubular 150AH.
And also
I have a Honda EM650 Petrol run Generator.

The battery gets abused so much because of constant power cuts. So I alternate them on and off. These were 2012 purchases.

APC 850va Pure Sinewave and Exide Tubular 150AH was INR 20,500 - Picked up in BTM Layout, Bangalore.

Honda EM650 Petrol Genset was 24,750 Picked up in Associated Electronics, Coimbatore.

Cheers,
Jai