In a three-phase system, with PF = 1, which is the correct expression for current I in terms of total power P and line-to-line voltage V_LL?

Prepare for the NCCER Electrical Level 2 Control Systems and Fundamental Concepts exam. Utilize flashcards and multiple choice questions with hints and explanations. Ensure success on your exam!

Multiple Choice

In a three-phase system, with PF = 1, which is the correct expression for current I in terms of total power P and line-to-line voltage V_LL?

In a balanced three-phase system, the total real power relates to line voltage, current, and power factor by P = √3 × V_LL × I × cosφ. With a power factor of 1, cosφ = 1, so P = √3 × V_LL × I. Solving for current gives I = P / (√3 × V_LL). This is the correct expression because it directly follows from the three-phase power relation and the unity PF assumption. The other forms either omit the √3 factor or place it in the numerator, which would yield incorrect current values for the same P and V_LL.

In a balanced three-phase system, the total real power relates to line voltage, current, and power factor by P = √3 × V_LL × I × cosφ. With a power factor of 1, cosφ = 1, so P = √3 × V_LL × I. Solving for current gives I = P / (√3 × V_LL). This is the correct expression because it directly follows from the three-phase power relation and the unity PF assumption. The other forms either omit the √3 factor or place it in the numerator, which would yield incorrect current values for the same P and V_LL.

More practice questions