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240V 3 Phase??

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klubie

Electrical
May 2, 2006
20
Is there such a thing as 240V 3 phase? I thought 3 phase was only achievable at 208V??
 
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Absolutely there is. There are numerous countries which don't follow the North American standards.

Most of Europe historically used either 240V or 220V single phase, now standardised at 230V. It's pretty common for 240V 1-phase input variable speed drives to produce an output of 240V 3-phase. In that case a standard 3-phase motor wired for 415V in star connection can be used with 240V 3-phase in a delta connection.

Other than that, with the right transformers you can have pretty much any three phase voltage you want within reason - once you get into the million volt region things get difficult!


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North American 240V 3-phase, while not as common as in the past, is far from unknown. Unlike a European 240V from a wye connection, the North American 240V would have come from a delta with the center point of one winding (generally between A and C) grounded. That way there is 120V line to "neutral" on two phases. The third phase (B per the NEC) will be 208V line to "neutral". Utilities will generally no longer provide new 240V delta services, but there are many still in use.
 
DavidBeach is absolutely correct and in most US cities the majority of urban/suburban residential services is at 240V/3ph with groups of houses fed as Davidbeach stated. Most older industrial facilities were fed with dual services, one metered at 240V/3PH for major loads and one at 120/240V, 1PH/3W for lighting and incidental loads.
 
US and Canada standard 120V/207V European standard 230V/400V (1F/3F) difference between these is sqrt(3) or 1.73 and it comes from phase angle between phases that 3 phase system has (ever seen Mercedes sign same goes for phasors in 3 phase system).
There are many other standards usually use bu Industries in Europe it is common to have 600V/1000V system for them.
Voltage levels in Europe goes according to 3F value
0.4KV
1KV
6KV
10KV
35KV
110KV
220KV
400KV
after 400KV we are using DC system because the losses are smaller on that voltage level and it is used by intercontinental connections :)
 
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