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If a balanced (symmetrical) 3 phase/4 wire power source is connected to a balanced 3 phase/4 wire load (impedance), I1 + I2 + I3 = 0 and In (neutral wire current = 0). In this case, the neutral wire can be removed and nothing changes.
If the power source is unbalanced, for example, In (neutral wire) would draw the imbalanced current.
Now, my question is - what happens in an unbalanced power source connected to same 3 phase load except with NO neutral wire connection (floating neutral). Seems to me I1 + I2 + I3 still wants to be zero, but with no neutral to carry imbalance, the imbalance will cause circulating line-to-line currents to flow such that the line voltages alter to satisfy the sum (I) = 0 formula. If this is correct, then the unbalanced power source will become even more unbalanced. Is this correct analysis?????
The reason I ask is because an end user is using a 3 phase autoxfmr with floating neutral (440 to 420V stepping). They have an unbalanced power
source. The drive mfg is recommending they either ground the floating neutral or install an isolation xfmr with grounded neutral. However, I'm not convinced grounding the neutral specifically eliminates the imbalance that originates at the power source.
Thanks.
If the power source is unbalanced, for example, In (neutral wire) would draw the imbalanced current.
Now, my question is - what happens in an unbalanced power source connected to same 3 phase load except with NO neutral wire connection (floating neutral). Seems to me I1 + I2 + I3 still wants to be zero, but with no neutral to carry imbalance, the imbalance will cause circulating line-to-line currents to flow such that the line voltages alter to satisfy the sum (I) = 0 formula. If this is correct, then the unbalanced power source will become even more unbalanced. Is this correct analysis?????
The reason I ask is because an end user is using a 3 phase autoxfmr with floating neutral (440 to 420V stepping). They have an unbalanced power
source. The drive mfg is recommending they either ground the floating neutral or install an isolation xfmr with grounded neutral. However, I'm not convinced grounding the neutral specifically eliminates the imbalance that originates at the power source.
Thanks.