Dual Input Power Supply

An automatic change over switch may be wired with dual supply , but i think it is not possible for an uninterrupted supply without batteries.

Sorry batteries required along with a change over for the two supplies.

The problem seems to be tied up in what you mean by UNINTERRUPTED. Perhaps the term is too specific for your application?

If you were to describe your load, we might be able to offer some suggestions that do not require batteries.

If you are operating motors, there could be some issues. Otherwise, you may be using something that converts the AC power to DC power in which case, many more options are available.

Looking forward to more information.

What happens if you have a power loss? The system you describe certainly would not help you in this case. Isn't that something you have to cover for to have an uninterrupted power supply? How often would the power supply fail and why? can you mitigate this risk?

Yes when both power supplys fail there is no output? How important is that output? Is it a temporary set up with high loads and power supply most likely to fail? Or is it a permanent setup that has to be protected whatever comes? More information needed.

Closed transition transfer switch

Yes you need one UPS.

From where you can get 2 Input powers?

One from Supply Co and the other Genset?

Any how if you are thinking of 2 Φs of the same source take it as one not two

You cannot connect 2 different power sources in parallel to one load unless both has synch system.

Load will be on only one source at a time unless you are using On-line UPS.

In case you of In-line UPS:

If UPS fails load be transferred only one of the sources only.

My boss advised all workers and collegues:

Think of making a Fool-Proof but NOT BLOODY-FOOL-PROOF.

So think of the second source of power a Genset, not 2 Φs from supply Co.

If your Setup is so important then contact supply Co to give you from 2 different Grids with automatic change power to your premises

Have a fine time!

Sir,

Thank you for the interest shown....

Load = EPABx

Input 1 = Supply Co.

Input 2 = One feeder from a common UPS which is away from this location and I have no control over it.

Usually both sources are ON

Presently the EPABx is connected to UPS. Sometimes the UPS source fails due to tripping of feeder/UPS

I have an option of installing a separate UPS....trying to avoid battery, since second source is readily available; Only objective is to avoid interruption.

Are the two sources phase-locked? Are the loads transformers or motors?

If the iron in their windings saturates, massive transient currents flow clearing fuses as only the winding resistance will determine the current. This phenomenon was refered to as 'offset' some 50 years ago in spot welder timers. The cure was to always connect power some 60 degrees after zero cross of voltage and always disconnect after full cycles (no half cycles). Also always start so the first half cycle is the same polarity.

My preference at the 10A current and with total insensitivity to the supplies' phasing would be to rectify (but not smooth) both supplies. Paralling the two rectifiers' output with a smoothing capacitor will provide the supply to an inverter thence to the load.