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Information on UPS

09/30/2017 6:54 PM

I have a transformerless 15kva/380v/3ph/50hz online UPS lying there in the workshop for some years now. My questions:- 1. Is it possible to convert it to a single phase - 220v/1ph/50hz for household use? If yes. 2. How can this be achieved?

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#1

Re: Information on UPS

09/30/2017 8:36 PM

Probably not...

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#2

Re: Information on UPS

09/30/2017 9:03 PM

While it can be converted it most certainly would not be possible for you to do this safely or cost effectively. (You will be wasting your money.)

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#3

Re: Information on UPS

09/30/2017 10:26 PM

I think it would be easier to find a couple of cheap second hand transformers one in, one out....how efficient this setup would be, might be an issue....I think I would just go with a standby generator...or maybe smaller ups on essential equipment....I have 3 on my TV's and computers, they are really only good for about 10 minutes of backup time....so really only good for momentary outages....

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#4

Re: Information on UPS

09/30/2017 10:35 PM

Well all you have to do would be to remove and replace the 6-pulse input rectifier with a full-wave bridge rectifier rated for 220V. Then you would have to add many more capacitors on the DC link, because for single phase UPS, you need a lot more capacitance to hold up the DC link bus when driven by single phase power. Then you would have to remove and replace the 6-pulse inverter section with an H-bridge inverter section. And then you would need to remove and replace the three-phase inverter control board with a single phase inverter control board. You would need to re-configure the batteries to provide the 220 V power and if the 380V UPS used boost converters to get the battery voltage up to the required potential, then the boost converters would need to be replaced as well. Or you could use one of these to convert 380V 3-P to 220V 1-P:

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#7
In reply to #4

Re: Information on UPS

10/02/2017 1:26 AM

Or you could also make it more efficient, less noisy, cheaper and smaller by using a SMPS instead of motors.

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#16
In reply to #4

Re: Information on UPS

10/02/2017 11:57 AM

So, what your saying is that if I wanted to convert a car to a boat, I would need to change almost every part, with the exception of the steering wheel. Or I could just go buy a boat.

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#17
In reply to #16

Re: Information on UPS

10/02/2017 1:26 PM

You could try to do both boat and car.

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#18
In reply to #16

Re: Information on UPS

10/02/2017 3:06 PM

Yeah, that was pretty much my intent.

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#5

Re: Information on UPS

10/01/2017 6:14 PM

(almost) anything's possible. It would probably be safer and easier to buy a three phase to single phase transformer, assuming you had a three phase supply available. The batteries are probably shot after years of neglect too, so I don't realistically see it being cost effective compared to just scrapping it and buying a new one.

What do you want to do with it as you are also going to need a source transfer switch unless you just want to connect some appliances directly in to it.

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#6

Re: Information on UPS

10/01/2017 11:30 PM

I'm going to assume that you're talking about a 15kva/380v/3ph/50hz power input that you want to convert to a 220v/1ph/50hz power input to the UPS. If that's the case, you might get lucky. When the power supply converts the 15kva/380v/3ph/50hz power input into a usable form for the UPS, It might consolidate the 3 phases into a single rectified DC source that charges the battery before the battery is inverted back to AC for the off-grid power. If that's the case, then you can just measure what that DC output is and just replace that "battery charger" part of the UPS with one that runs off of your house current (220v/1ph/50hz).

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#10
In reply to #6

Re: Information on UPS

10/02/2017 4:47 AM

Thanks to you all.

The rated i/p and o/p voltage of the ups is 380v/3/50Hz.

The available supply systems voltage is 220v/1/50Hz. This is the intended i/p and also the range of o/p i want from the ups.

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#8

Re: Information on UPS

10/02/2017 2:41 AM

Dear odezimesteve,

You have not indicated the reason for conversion to single phase. What is the problem in the present system.?

The answer for your question is

Yes technically it is possible, to convert 15kva/380v/3ph/50hz supply to D.C, and again invert it to single phase A.C supply.

But cost wise you have to work out the cost effectiveness and decide.

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#11
In reply to #8

Re: Information on UPS

10/02/2017 4:51 AM

Thanks Dhayanandhan.

The rated i/p and o/p voltage of the ups is 380v/3/50Hz.

The available supply systems voltage is 220v/1/50Hz. This is the intended i/p and also the range of o/p i want from the ups.

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#12
In reply to #11

Re: Information on UPS

10/02/2017 7:52 AM

In that case, your UPS will be useless.

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#9

Re: Information on UPS

10/02/2017 3:56 AM

Is picking up the phone and talking the question through with the equipment's original manufacturer completely off the agenda, then?

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#13

Re: Information on UPS

10/02/2017 8:04 AM

Because there is "no transformer" you will most likely have to come up with several replacement parts on the main circuit board. To find or figure out which parts, you will need to completely understand the circuit that is provided. That translates into way too much work for most questions like this.

Most devices are so customized that it is less expensive to start fresh than to try to convert something for a use that is different from the intended design. And, while you say that it is transformerless, I would wager that if you looked inside you would in fact find both chokes and small, high frequency transformers that are the key to the design.

Another aspect of converting three phases to one is that no ground or common is used. You didn't indicate if it was a 3 or 4 wire output. If it is a 3 wire output, then your configuration is a delta and you need a wye (4 wire) output. You could achieve this with three transformers, but then you would have blown your nearly free scheme completely out of the water.

The other consideration is that by using only one third of the supply to generate the desired single phase causes an imbalance that will likely accelerate the ageing of the components and bring about pre-mature failure. So, in the long run, you will spend more money trying to convert unless you just happen to have a motor-generator set lying around.

In conclusion, yes it is possible, but the effort makes it not likely to be practical.

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#14

Re: Information on UPS

10/02/2017 9:31 AM

What's a UPS?

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#15
In reply to #14

Re: Information on UPS

10/02/2017 9:48 AM

Besides it being one of the largest parcel shipping company, presumably a UPS in this discussion is an Uninterruptible Power Supply. You are correct that this was never explicitly stated.

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#19
In reply to #15

Re: Information on UPS

10/02/2017 3:08 PM

Come on guys, while the acronym was not explicitly defined, from the context provided it was clear enough to all here (in my opinion) that the discussion was regarding an Uninterruptible Power Supply.

Lets not be too picky on a new CR4 poster.

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#20
In reply to #19

Re: Information on UPS

10/02/2017 8:13 PM

I'd say the thing in #17 is a Uniquely Powered Swimwagon.

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Bazzer Englander (1); Brave Sir Robin (2); Dennis R. Levesque (2); dhayanandhan (1); Ivanov327950 (2); jack of all trades (2); NotUrOrdinaryJoe (1); odezimesteve (2); PWSlack (1); redfred (3); Rixter (1); SolarEagle (1); tonyhemet (1)

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