Formula For Line Current And Phase Current

Three-phase Currents:

\[ I_{line} = \sqrt{3} \times I_{phase} \quad (\text{Star Connection}) \] \[ I_{line} = I_{phase} \quad (\text{Delta Connection}) \]

Connection Type:

Current Value:

Calculate:

Phase to Line Current Line to Phase Current

Result:

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1. What Are Line And Phase Currents?

In three-phase electrical systems, phase current refers to the current flowing through each individual winding or phase, while line current refers to the current flowing in the transmission lines connecting the source to the load. The relationship between them depends on the connection configuration (star or delta).

2. How The Calculator Works

The calculator uses the fundamental three-phase current relationships:

\[ \text{Star Connection: } I_{line} = \sqrt{3} \times I_{phase} \] \[ \text{Delta Connection: } I_{line} = I_{phase} \]

Where:

\( I_{line} \) — Current in the transmission lines (A)
\( I_{phase} \) — Current through each phase winding (A)
\( \sqrt{3} \) — Approximately 1.732 (mathematical constant)

Explanation: In star connection, line current equals phase current. In delta connection, line current is √3 times the phase current due to the 120° phase displacement.

3. Three-Phase System Fundamentals

Details: Three-phase systems are the standard for power generation, transmission, and distribution worldwide due to their efficiency and power delivery capabilities. Understanding current relationships is crucial for proper system design and protection.

4. Using The Calculator

Tips: Select the connection type (star or delta), enter the current value in amperes, choose calculation direction (phase to line or line to phase), and click calculate. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between star and delta connections?
A: Star connection has a neutral point and phases connected to a common point. Delta connection forms a closed loop with phases connected end-to-end.

Q2: Why is line current higher in star connection?
A: In star connection, line current flows directly through each phase, so they are equal. In delta, line current is the vector sum of two phase currents.

Q3: When should I use star vs delta connection?
A: Star is preferred for long-distance transmission and systems requiring neutral. Delta is common for motor connections and industrial applications.

Q4: How does this affect power calculations?
A: Total power in balanced three-phase systems is √3 × V_line × I_line × power factor, regardless of connection type.

Q5: Are these relationships valid for unbalanced systems?
A: These formulas apply to balanced systems. Unbalanced systems require more complex analysis using symmetrical components.