Dual Input Auto Changeover Unit

Kind of an erroneous concept if you ask me. Are the two "sources" completely different, i.e. from two totally independent generation systems? If not, the entire thing is an effort in futility.

But be that as it may, this appears to be a functional specification that you need to provide. I would use a small PLC or "Smart Relay" for some basic logic. Put a voltage sensing relay on each of the two sources and set it up to trip if it is over or under spec. Feed those into the PLC and have the logic look at them both and if one trips, AND THE OTHER IS HEALTHY, then change contactors. Your functional spec makes no mention of what to do if they are both bad, but I would open both contactors in that case.

The big looming problem I see is, if your incoming line is bad, where is the control power for the logic and contactors going to come from? Better figure on a UPS, and if so, someone needs to define hold-up time.

As I said in the beginning, this is a flawed concept at the get go.

Thank you very much for valuable suggestion and analysis.

Yes as you said, i will design it using PLC and with some timers.

You want to design and build your own ATS, right?

While it is possible to build an 80A three phase Automatic transfer switch, it is NOT something you want to play around with unless you really know what you are doing AND are familiar with all the electrical standards and regulations regarding them.

I would suggest you just buy one instead (or at the very least the control electronics which will allow correct synchronising between two supplies). Of course the whole concept is pointless for a three phase system unless you have a ring-main system or backup generation supply (two separate supply sources independant of one another).

A really simple system using parallel contactors (with mechanical interlocks), timers, protection electronics and a UPS feeding the DC power supply system (to prevent power supply down time) is probably the simplest (and safest) solution if you want something simple.

Don't forget to consult your local electrical codes and standards!

Why not just buy one?

It could have been installed and working by now.

If you really want to build one for sheer exhilaration then start with a functional flow diagram.

Thank you Wal,

Please let me know what is the price of it, and also guide me who is the manufacturer of this product.

thanks in advance.

If you click on the link there is a selection to choose from complete with prices.

You want to be looking at your friendly neighborhood generator supplier or switchboard builder as possible local sources.

Where are you? Maybe a CR4 contributor near you can give locality specific advice or go shopping with you.

Thank you Wal,

I am sitting in INDIA, I am looking for a switch board builder, if you can suggest any vendor, it will helpful for me. other wise no problem i will findout one through my indian friends.

I am not find any link in your post, if you dont mind, Please post the link once again.

Thank you very much once again for the suggestion and the valuable time spent on my post.

In my post #5, the words just buy one are hyperlinked. That's why they are blue and underlined.

You're most welcome. Your Indian friends are the best folk to help you with local procurement.

Vendors/brand names...this is a basic piece of switchgear. Get one with a warranty that will be honored and supported.

http://dir.indiamart.com/impcat/automatic-transfer-switch.html

http://www.alibaba.com/trade/search?Country=IN&SearchText=amf+panel&IndexArea=product_en&fsb=y

Dear Mr.Bai

Thank you very much in identifying indian based manufacturer