If single phase voltage level is 230V than why three phase
voltage level is not 660V ?, but it is only 440V.

Answer Posted / m.ubaidullah khan

In three phase power line, each phase is 120 degree from the other phase.therefore, when we draw a graph of phases then two phases have positive values then at the same time the third one has negative value so we can calculate and use only two phases at a time.all three phases changes their position every time so the two phase may be phases 1 &2/phases 1&3 or phases 2&3 gives the values and at the same times phase 3 or 2 or 1 will be at negative interval respectively so cannot be calculated or contribute the value. that's the reason we use 440v instead of 660v.

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