[Aroy]

Originally Posted by theredliner

After getting tired of too many powercuts in the recent past, I'm contemplating getting an inverter-UPS for home. I checked the requirement through Luminous site and it showed that I'd need a huge 3.5 KVA one, that too without adding any AEH appliance to the calculator's list.

At the most, at any time,
4x fluorescent tubes
2x LED bulbs/CFLs
1x incandescent bulb
1x sub 200l refrigerator
1x 32" LED backlit LCD TV
1x DTH STB
1x gaming desktop connected to 1KVA UPS (550W PSU, 1x 21.5" LED backlit monitor, 1x 200W sound system running at low volume)
1x work laptop

would be running simultaneously (excluding AEH stuff). Would the above really need a 3.5KVA inverter?

The UPS ratings are based on peak consumption as well as on efficiency and PF factor. The last two derate the capacity by between 10% to 20%. So if the peak load is 3KVA and derating 20% you need 3.75KVA rating!

If you take the 1KVA UPS, Laptop and the Refrigerator out, then you will have less than 800W. The reason is that the refrigerator requires starting current that is at least twice the running current, and UPS and Laptop are unnecessarily connected to the inverter. If your UPS has small batteries, it will be better to increase their capacity, rather than stressing the Inverter.

You would also save Inverter rating if you replace the tube lights (which consume upwards of 70W for 40W tube) with LED, that would save 4 x (70 - 10) = 240W around 1/4 KVA of the UPS capacity. Replacing incandescent bulb will also save at least 40W.

On the whole a consumption Audit of electrical devices is needed before installing an Inverter. With smaller load on Inverter you can get bigger batteries (for the same cost) which will give you longer backup capability.

[theredliner]

Originally Posted by Aroy

The UPS ratings are based on peak consumption as well as on efficiency and PF factor. The last two derate the capacity by between 10% to 20%. So if the peak load is 3KVA and derating 20% you need 3.75KVA rating!

Thanks. Let me explain the situation more clearly so that I can ask some noobish questions,

I actually have no need to run a refrigerator during power cuts. Let me assume that I need to run only fans, lights and a television on backup which consume around say 500W.
However, if at the time of power cut, a desktop computer, a refrigerator and an iron are also running and the actual consumption is around 1700W (just an assumption), will a 1.5 KVA (PF of 0.7) overload immediately or will the surge load be handled for a while so that I can go ahead and turn off the unneeded load? If it is the latter, how long does it last for the regular home inverters?

Originally Posted by aim120

But Incandescent bulb in this day and age. In my house the last incandescent bulb and tubelight was removed some 15 years ago and all CFL bulbs was removed some 4 years ago.

I live in a rented house and unfortunately, some rooms do not have a slot for anything other than fluorescent lamps.

[rdst_1]

Originally Posted by theredliner

However, if at the time of power cut, a desktop computer, a refrigerator and an iron are also running and the actual consumption is around 1700W (just an assumption), will a 1.5 KVA (PF of 0.7) overload immediately or will the surge load be handled for a while so that I can go ahead and turn off the unneeded load? If it is the latter, how long does it last for the regular home inverters?

You will need to run new wires for the inverter. When doing so, you will only provide connection to the devices you need to run on the inverter and not to every point in the house. So there is no point in worrying about overload and having to turn off devices since they won't be connected to the inverter anyways.

I live in a rented house and unfortunately, some rooms do not have a slot for anything other than fluorescent lamps.

You get LED bulbs for every kind of fixture these days.

[Aroy]

Originally Posted by theredliner

Thanks. Let me explain the situation more clearly so that I can ask some noobish questions,

I actually have no need to run a refrigerator during power cuts. Let me assume that I need to run only fans, lights and a television on backup which consume around say 500W.
However, if at the time of power cut, a desktop computer, a refrigerator and an iron are also running and the actual consumption is around 1700W (just an assumption), will a 1.5 KVA (PF of 0.7) overload immediately or will the surge load be handled for a while so that I can go ahead and turn off the unneeded load? If it is the latter, how long does it last for the regular home inverters?


I live in a rented house and unfortunately, some rooms do not have a slot for anything other than fluorescent lamps.

Check your wiring. At the least you will have different circuits for Light and Power. Connect Inverter to "Light Circuit". Relocate all appliances that will not run on Inverter to the "Power Circuit". In case you do not have Power outlets for refrigerator and UPS, find the nearest one and use a heavy duty extension board(s).

Regarding Tube Lights, you get LED replacements for tube lights. Not only do they consume less power, they are generally more pleasing to the eye compared to the harsh white tube lights.
https://www.amazon.in/Nordusk-light-...be+light+price
https://www.amazon.in/Crompton-Light...led+tube+light
https://www.amazon.in/Eveready-20-Wa...led+tube+light
https://www.amazon.in/Eveready-5-Wat...led+tube+light

[diyguy]

I had some miscreants jump over our wall and steal some of our stuff in the backyard - steel drum, old washing machine metal stands and one metal tap. So I fitted seven 10W Philips LED tubes of 2 ft length. These come on now at 6:30pm and turn off at 5:45am by a timer switch. Combined these consume only 60+w and illuminate all corners of our house. Was mentioning to my mom, earlier one bulb would consume as much as 7 led battens today.

[sagarpadaki]

Originally Posted by diyguy

I had some miscreants jump over our wall and steal some of our stuff in the backyard - steel drum, old washing machine metal stands and one metal tap. So I fitted seven 10W Philips LED tubes of 2 ft length. These come on now at 6:30pm and turn off at 5:45am by a timer switch. Combined these consume only 60+w and illuminate all corners of our house. Was mentioning to my mom, earlier one bulb would consume as much as 7 led battens today.

Which software, hardware combination do you use to control the lights? Do LED battens these days come with smart controls?

[prithm]

Originally Posted by Thad E Ginathom

Convenience machine! Power cut just as we wanted to eat, so we turned it on to run the microwave

Greetings Sensei.

After much hue, shouting and fighting I was finally able to get the 3.5kVa purchased and installed in Chennai.



This is actually 10% of what I planned for, but unfortunately due to travel delays and ad-hoc vacation plans I somehow managed to get it fixed first.

The problem that I have is the space that this entire set up occupies.

I have ample space under our outdoor staircase which I am planning to convert as battery storage location. Have to construct a room with grill door and covered with plastic or mica sheets. Planning to keep the inverter indoor. But that would mean I need to get an extra long DC wires to connect between inverter and battery. Hope this pictorial explains my predicament.



The predicament that I have is the “Last Mile Connection” that I have highlighted above. How do I connect the inverter with the battery terminals (using DC cables and placed outside the house). DC cables are not available longer than 5 feet to max (at least where ever I asked) ?



Possible solution :

1. Take the inverter to the battery room. Absolutely not possible due to extreme climate variation, unwanted attention and usage issues.
2. Keep the inverter in home, batteries outside (closed enclosure below the stairs) with a hole in the adjoining wall so that I can pass the cable through the hole (yellow circle) from inside the home, I connect multiple 5 feet DC wires (screw and bolt covered by insulation tape) get the (+) and (-) connected to inverter. Is this advised ?

Do you guys see any other solution to connect the inverter and battery which are placed apart (approx. 5-6 feet) ?

[diyguy]

Originally Posted by sagarpadaki

Which software, hardware combination do you use to control the lights?

I use a wifi switch called sonoff pow. It has an app called eWeLink, whose screenshot I had shown. It has timer and schedule capability apart from monitoring power consumption, costs between 10-12$ on aliexpress.

[Jaggu]

Originally Posted by prithm

2. Keep the inverter in home, batteries outside (closed enclosure below the stairs) with a hole in the adjoining wall so that I can pass the cable through the hole (yellow circle) from inside the home, I connect multiple 5 feet DC wires (screw and bolt covered by insulation tape) get the (+) and (-) connected to inverter. Is this advised ?

Do you guys see any other solution to connect the inverter and battery which are placed apart (approx. 5-6 feet) ?

Just drill a hole and connect the battery pack, no big deal. Longer wire means more loss and chances of things going wrong, right from a rodent attack to much more. Drill a hole, do a good PVC piping through which wires can be drawn.

[prithm]

Originally Posted by Jaggu

Just drill a hole and connect the battery pack, no big deal. Longer wire means more loss and chances of things going wrong, right from a rodent attack to much more. Drill a hole, do a good PVC piping through which wires can be drawn.

Thanks Jaggu. How much of a backup duration loss will I lose if I shift from 30 cm jump wire to 2 feet wire ? I know it will involve ohm, but I just want a ball park number in terms of hours or minutes of back up loss due to long wire.

[R2D2]

Originally Posted by prithm

Thanks Jaggu. How much of a backup duration loss will I lose if I shift from 30 cm jump wire to 2 feet wire ? I know it will involve ohm, but I just want a ball park number in terms of hours or minutes of back up loss due to long wire.

Going from 30 cm (approx. 1 ft) to 2 ft. with the same wire gauge will lead to very small increase in the resistance probably by 1/100 of an Ohm if not lower over a 2 ft. length. So don't worry about it.

Make sure this is a single length of 2 ft and not 2 separate pieces of 1 + 1 ft joined together. Unless of course the 2 pieces are crimped with proper connectors and then **bolted** together. Whoever does this job needs to use the proper tools and connectors.

Proper crimping of connectors and ensuring good quality connections on either side of the cable is essential. Otherwise it can create more resistance to current flow than just the extended cable length.

[Aroy]

Originally Posted by prithm

Greetings Sensei.
=======
Do you guys see any other solution to connect the inverter and battery which are placed apart (approx. 5-6 feet) ?

Originally Posted by Jaggu

Just drill a hole and connect the battery pack, no big deal. Longer wire means more loss and chances of things going wrong, right from a rodent attack to much more. Drill a hole, do a good PVC piping through which wires can be drawn.

. Yes a hole is the way.
. 5-6 feet is not a very long distance.
. Cables are available in long rolls with Truck Electricians. They will have long lengths as the battery to starter distance is about 5 meters for a truck.
. You can calculate the resistive loss of a cable at a given current and a given length. So for a longer cable you just increase the cross section size.
. One thing that I will recommend is to have a small fan, say 50W blowing across the batteries towards the opening. That will keep the air circulating and blow away the hydrogen out. You can either get a 220V fan, or best get an instrumentation fan rated for 24x7 duty connected to the batteries.

[prithm]

Originally Posted by R2D2

Going from 30 cm (approx. 1 ft) to 2 ft. with the same wire gauge will lead to very small increase in the resistance probably by 1/100 of an Ohm if not lower over a 2 ft. length. So don't worry about it.

Make sure this is a single length of 2 ft and not 2 separate pieces of 1 + 1 ft joined together. Unless of course the 2 pieces are crimped with proper connectors and then **bolted** together. Whoever does this job needs to use the proper tools and connectors.

Proper crimping of connectors and ensuring good quality connections on either side of the cable is essential. Otherwise it can create more resistance to current flow than just the extended cable length.

Thanks R2D2 san. The part about bolting 2 lengths of wires should not cause any issues right if I cover it with good load of insulation tape or heat shrink ?

Originally Posted by Aroy

One thing that I will recommend is to have a small fan, say 50W blowing across the batteries towards the opening. That will keep the air circulating and blow away the hydrogen out. You can either get a 220V fan, or best get an instrumentation fan rated for 24x7 duty connected to the batteries.

Thanks Aroy. As you can see from the diagram plan, its going to be a small room under the staircase (outdoor). I am planning to make horizontal seperation (using some stone slab) so that I can have the opportunity to add battery number or transfer inverter outside provided I get a good strong metal door made.

For ventilation, I thought of having few small plastic PVC pipes put out on the top so that gas can escape. Something like this. There are no chance of sunlight shining directly on this, but summers in Chennai is harsh with humidity.

[R2D2]

Originally Posted by prithm

Thanks R2D2 san. The part about bolting 2 lengths of wires should not cause any issues right if I cover it with good load of insulation tape or heat shrink ?

Heat shrink is way better than insulation tape which can come off after a while. Just make sure the crimping to the connectors is done properly. Very important when those wires will be carrying 10-40A, or more, of current when the set is discharging or charging.

For ventilation, I thought of having few small plastic PVC pipes put out on the top so that gas can escape. Something like this. There are no chance of sunlight shining directly on this, but summers in Chennai is harsh with humidity.

Vent pipes are passive ventilation and should suffice. But I'd advise a small exhaust fan installed since the area/room is small and you have 4 batteries that can generate and vent a lot of gas when charging. It'll also help get rid of heat build up by pulling in outside air.

[Thad E Ginathom]

Gentlemen, if a fan is installed near the batteries, it's it free from spark risks?