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View Full Version : Working of 5KVA or more UPS........


RRITESH KAKKAR
10-13-2011, 04:53 PM
Hi,

I am interested to know about working of High KVA rating UPS working........
As UPS convert DC to AC .......
Like online and offline UPS.

RRITESH KAKKAR
10-14-2011, 03:45 PM
please help.....
like why modulation wave will be best for operation of UPS..??

SgtWookie
10-14-2011, 04:02 PM
Here is a link to a fellow's page who built a 2KVA inverter:
http://192.197.62.35/staff/mcsele/i2k.htm

It's good reading for background information.

If you want a 5KVA unit, you should buy one rather than try to build one.

RRITESH KAKKAR
10-14-2011, 04:18 PM
Yes i have seen it and gone through it..........
i want to start with 30watt then move to high rating as this is my cool project...if you want to give any other project that is good i can try it also.

praondevou
10-14-2011, 04:52 PM
Yes i have seen it and gone through it..........
i want to start with 30watt then move to high rating as this is my cool project...if you want to give any other project that is good i can try it also.

Starting with 30W shouldn't be a problem. Going towards 5kVA later on will require that you change the whole power part and layout, i.e. it will be a different project.

Also, for 30W or 5kVA you will probably not use the same topology.
There are different topologies for every power range.

What will be the specs of your UPS?
Input voltage range
Output voltage
Output power
PFC at the input?
Battery backup time
3 phase / monophase input/output?
Protections? input/output overvoltage/overcurrent limits and UPS behaviour, inverter to mains synchronisation lock-in range and speed.

This is not a small project so you should figure out what you want to do before starting to mount any circuits.
You can go with what Wookie suggested or build one from scratch, which will take you months... at least. :-)

You basically will need a rectifier/charger, inverter and static switch.


Btw, you want a cool project? Then why not build something that doesn't exist? There are already tons of UPS available on the market, in all power ranges....

RRITESH KAKKAR
10-15-2011, 02:25 AM
Btw, you want a cool project? Then why not build something that doesn't exist? There are already tons of UPS available on the market, in all power ranges....

OK, first you tell then what to build...??

Georacer
10-15-2011, 10:18 AM
Don't get disappointed. I have a friend who frowns upon many of my projects, just because they don't have a practical use.
Just build what makes you happy, that's my opinion.

RRITESH KAKKAR
10-15-2011, 11:06 AM
No your suggestion are welcome....which project is nice.
pls tell...

kubeek
10-15-2011, 02:25 PM
Find some 300-500w UPS, dead or alive, take it apart and salvage the components. Then look at the driver PCB, try understanding why is there each of the parts, and when you think you know it all start designing your circuit.

RRITESH KAKKAR
10-15-2011, 03:23 PM
No your suggestion are welcome....which project is nice.
pls tell...

praondevou
10-16-2011, 03:07 AM
I'm not saying don't build the UPS nor it isn't a nice project, but you will spend TIME and MONEY on 5kVA.
Then, when being discussed on THIS forum you will get to a point where people won't be allowed to help you because, to save cost, your project will not necessarily be isolated from mains. Even if it was isolated it will still contain high /dangerous voltages in various parts of the system. If you think you have the experience to undertake such an endeavour you will need to get help elsewhere, otherwise I suggest you try something less time and cost intensive and less dangerous.


Also, what's is your location and part distributor access? There were some people here, who had a hard time finding parts
that were suggested to them, because they were either not available or much to expensive...

There are so many things one could build... I prefer projects that are useful to me or to others. Maybe you can think of
something you could use at home. It's hard to suggest something if we don't know what your interests are. You could suggest something you always wanted to build but have no idea where to start for example...

RRITESH KAKKAR
10-16-2011, 03:29 AM
Also, what's is your location and part distributor access? There were some people here, who had a hard time finding parts
that were suggested to them, because they were either not available or much to expensive...

Don't worry about part, i will try it.


There are so many things one could build... I prefer projects that are useful to me or to others. Maybe you can think of
something you could use at home. It's hard to suggest something if we don't know what your interests are. You could suggest something you always wanted to build but have no idea where to start for example...

OK, my interest till ow is in Electronics and Dish setups..

and if we talk about UPS i will make some change like i will make it wireless monitor for viewing o/p response of freq., voltage, current and % of load...
and i am thinking of connecting it to computer like for viewing as monitor through internet, like that, etc........

your idea are also welcome.

RRITESH KAKKAR
10-16-2011, 02:15 PM
Please tell for square wave of UPS which chip or multi vibrator should be preferred...??
For 30-50VA ups not 5KVA..

kubeek
10-16-2011, 03:20 PM
For a square wave and 50-60Hz, a 555 will suffice.

RRITESH KAKKAR
10-16-2011, 03:27 PM
Hi kubeek,
Most of people were saying it has not god regulation something like taht...and in my computer small UPS has many op-amps...
can you tell me about them?
thanks

kubeek
10-16-2011, 03:42 PM
Well, there is a huge difference between a square wave ups and other kinds.
Also, you were asking what is a good multivibrator for a square wave ups. This doesnīt mean that to build a complete UPS with all protections etc. you donīt need anything else than a 555.

Another thing is that the multivibrator depends on what topology of ups and what transformer you use. For your wattage a 555 can be enough, for higher wattages and different modulation schemes, other parts like tl494 might be better.

RRITESH KAKKAR
10-16-2011, 03:48 PM
OK, what about 4047..?
and i will use 12-0-12V transfer of 3-5amps

kubeek
10-16-2011, 04:20 PM
The datasheet suggests 2.2M and 1000 pF for 100Hz which are both rather high impedance values, so the 4047 oscillator will be much more suspect to switching noise than the 555 one. That is because a 555 can output larger current than 4xxx series, so the cap can be larger and the resistor lower for the same frequency, which makes it harder for noise to creep into the oscillator.