# uninterruptible power supply

Discussion in 'Electronics Homework Help' started by Syed Waqar Ali, Mar 10, 2016.

1. ### Syed Waqar Ali

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Jan 13, 2016
Hi guys!

Recently, I am working on a smart grid project. where i need an "Uniterruptible Power Supply" to keep my things (Electrical circuits implemented) working in case power will make out of the service, I need ur help in designing this supply, do share ur ideas, circuit diagrams etc...
Supply requirements is as follows:
I) Its ground should be isolated from the main supply.
ii) it should has recharge able batteries so that after power cut off circuit's biasing would be provided by these batteries, and during main supply it gets charging and automatic cutoff as it gets full charged.
iii) I need Dual supply , capable of providing both + ad - 30 Volts and fixed 5 and 8 volts.
Thanking in anticipation

2. ### Gryd3

4,098
875
Jun 25, 2014
Not much demand for an isolated ground... but it has it's uses. I hope you have other protection mechanisms in place.
8V is also an odd request.
Can you please confirm the outputs in more detail?
+ and - 30V DC or AC?
5V and 8V DC or AC?
What kind of amperage do you expect to draw from these supplies?

3. ### Syed Waqar Ali

16
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Jan 13, 2016
i) the supply is supposed to draw 1 ampere current.
ii) It should be AC to DC power supply, means it takes main supply as AC and converts this into DC supply outputs( + and - 30 and 5 volts fixed).
iii) Isolated ground is needed to separate our system ground from the supply..

4. ### Gryd3

4,098
875
Jun 25, 2014
You told me 1Amp draw, but for what rail?
1 Amp for each of the +30VDC, -30VDC, 8VDC, and 5VDC?
Or is this... 1 Amp 'input' the the regulator? (That's at least 100W which is kind of high...)

If you really want it isolated, you will want an isolation transformer... this breaks the direct electrical connection from the Live, and Neutral lines. The ground is not so much an issue usually... but your 'system' is shrouded in mystery. if you share more detail we can help there too...
Does your supply need to provide those 4 voltage with their own ground, or with a single common?

5. ### Syed Waqar Ali

16
0
Jan 13, 2016
Actually, We are implementing a system consists of electronic circuitry, including sensors and micro controller, on a grid station at 11Kv line potential to monitor its parameters like voltage , power etc (real time monitoring)...
to provide biasing to our circuits we need a Battery that should provide uniterruptible supply to these equipment so that no data should be missed out. This battery unit should include rechargeable batteries that continues its charging during main supply is on and as it cuts off the back up should be provided by switching mode to batteries charging out there. but we need a mechanism to isolate them as these get fully charged to increase their lives.

as system(circuits) are installed on the secondary of PT providing 110 volts(step down from 11kv), we need them to be isolated from the supply (main) provided to the battery just to keep isolation.

As far as rating is concern, we need at least 1 amps to draw from +-15 supplies because our circuit's ics demands not enough load current.
and fixed 5 volts rating is depending on a router adapter we are going to install there, for ethernet still not finalized.

6. ### Gryd3

4,098
875
Jun 25, 2014
This is beginning to feel like a project you should be hiring an engineer to build for you.