Three Phase Current Formula

3-Phase Current Formula:

\[ I = \frac{P_{kW} \times 1000}{V \times PF \times \sqrt{3}} \]

Current (I): amps

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1. What is the Three Phase Current Formula?

Definition: This calculator computes the current in a three-phase electrical system based on power, voltage, and power factor.

Purpose: It helps electricians and engineers determine the current flow in three-phase power systems for proper equipment sizing and safety.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ I = \frac{P_{kW} \times 1000}{V \times PF \times \sqrt{3}} \]

Where:

\( I \) — Current (amperes)
\( P_{kW} \) — Power (kilowatts)
\( V \) — Voltage (volts)
\( PF \) — Power factor (unitless, between 0 and 1)

Explanation: The formula converts kW to watts (×1000), then divides by the product of voltage, power factor, and √3 (approximately 1.732) which accounts for the three-phase configuration.

3. Importance of Current Calculation

Details: Accurate current calculation ensures proper wire sizing, circuit breaker selection, and prevents equipment damage from overcurrent.

4. Using the Calculator

Tips: Enter the power in kW, line voltage (default 480V), and power factor (default 0.8). Power factor must be between 0.01 and 1.

5. Frequently Asked Questions (FAQ)

Q1: What is power factor?
A: Power factor is the ratio of real power to apparent power, representing how effectively current is being converted into useful work.

Q2: Why √3 in the formula?
A: The √3 accounts for the phase difference in three-phase systems (120° between phases).

Q3: What's a typical power factor value?
A: Motors typically have 0.8-0.9 PF, while purely resistive loads have 1.0 PF.

Q4: Can I use this for single-phase systems?
A: No, use the formula \( I = P_{kW} \times 1000 / (V \times PF) \) for single-phase.

Q5: How do I measure actual power factor?
A: Use a power quality analyzer or power meter that provides PF measurement.