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**Home ⇒ Overview Courses ⇒ Electrical engineering ⇒ Three-phase Current ⇒ Determine the Total power**

### How to determine the Total power by the Line values

Phase values are often not or difficult to access. In addition, the line values are particularly important for the electrical protection in the control box. Is there an equation for determining the total three-phase power with line values, which applies to both star and delta connection? There is one:

**Regardless of how the load is connected to the three-phase system, the three-phase power can be calculated by using the formula P = √3 x U x I**

Some comprehension questions:

Does the Line voltage change when switching from star to delta? And if so, how?

How must the line current change when switching from star to delta?

How must the line current change when switching from star to delta?

- The
**line voltage**corresponds exactly to the voltage that you tap at the 3-phase socket. Of course, this voltage**does not change**when switching from star to delta. - As we have learned in the previous chapter "Power in Star and Delta", the power in Delta is 3 times higher than in star. If the Line voltage in star and Delta is the same, then the Line current in Delta must be 3 times higher than in star.

I_{Line Delta}= 3 x I_{Line Star}