3 phase 440V AC 60Hz (IT) to 2 phase 220V AC distribution design

[Michael2009]

Hi Guys,

I have 3 phase 440V AC 60 Hz as incoming. is LV IT system 3 wiere without neutral distribution.
How can i get 2 phase distribution as 220V AC (without N distribution)?
Can i just tap L1 and L2?

Some people tell me yes
Some say i need Isolation transformer ...

thanks for clearing my doubt

 

[wroggent]

What angle are you looking for between the 2 phases on the 220V system?

 

[protoslash]

if you take 2 phase from 3 phase 440V, you still get 440V phase to phase voltage. How are you getting 220v?

 

[edison123]

You will need a 440V / 220 V step down or a centre tapped 440 V auto transformer.

Muthu

http://www.edison.co.in

 

[waross]

Are you sure that you don't need 220 Volts single phase?
Do you need more than 1/3 capacity?
You may add an autotransformer to develop 220 Volts single phase from three phase. One phase will feed the autotransformer directly with 1/3 capacity.
The other two phases will act as the open side of an open delta. (North American open delta, not European).
This will form a virtual transformer that will act in parallel with the phase to which the autotransformer is connected directly.
This will also supply 1/3 of the transformer bank capacity for a total of 2/3 or the transformer bank total capacity.
That is, a single phase load across one phase of a three phase bank will have a capacity of 2/3 of the three phase capacity.
If you want two phases, you will need two autotransformers, across two phases.
If you need Historical two phase at 90 degrees, you will need a Scott connection.

You have not provide enough information for us to comment on a grounding scheme.
If you need a grounded circuit(s) and the supply must remain ungrounded then you will need the extra expense of isolation transformer rather than using autotransformers.

Bill
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"Why not the best?"
Jimmy Carter