The difference in load current with 3 Wire, 4 Wire and Inside delta power wiring configurations.

3 Wire and 4 Wire Power Connections

There are 4 main ways of connecting 3 phase Power Control equipment. 

4 Wire Star

Generally speaking 4 wire is required for unbalanced loads. the neutral current needs to be referenced in order to determine, and have good control of the power. 

For 50kW, 400VAC L-L Current in 4 wire system

50,000/(sqrt(3)*400) = 72 Amp rms per phase

 

Open Delta (6 Wire)

Inside Delta is used when you wish to reduce the current draw by a factor of 0.57 . generally used in cost sensitive applications

For 50kW, 400VAC L-L Current in 4 wire system

 50,000/3 = 16666.67kW

16666.67/(400) = 41.7 Amp rms (this is the rms current seen inside the delta tirangle)

3 wire Star or 3 Wire Delta

3 wire star or 3 wire delta is the most common and the simplest to install. You can get control issues with unbalanced loads

50,000/(sqrt(3)*400) = 72 Amp rms per phase

For any questions or further clarifications please contact out technical team.

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