3 Phase Heater Current Calculation 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 3-Phase Heater Current Calculation?

Definition: This calculator determines the current drawn by a three-phase electric heater based on power, voltage, and power factor.

Purpose: It helps electrical engineers and technicians properly size conductors, circuit breakers, and other components for heater circuits.

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, typically 1.0 for heaters)

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

3. Importance of Current Calculation

Details: Accurate current calculation ensures proper wire sizing, overcurrent protection, and prevents equipment damage or safety hazards.

4. Using the Calculator

Tips: Enter the heater power in kW, system voltage (default 480V), and power factor (default 1.0 for resistive heaters). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the power factor 1.0 for heaters?
A: Electric heaters are purely resistive loads, which have a power factor of 1.0 (unity).

Q2: What voltage should I use?
A: Use the line-to-line voltage of your three-phase system (common values: 208V, 240V, 480V, 600V).

Q3: Can I use this for non-heater loads?
A: Yes, but adjust the power factor accordingly (motors typically 0.8-0.9, lighting 0.9-0.95).

Q4: Why multiply by 1000 in the formula?
A: This converts kilowatts to watts (1 kW = 1000 W) since the formula uses basic electrical units.

Q5: How does this differ from single-phase calculation?
A: Single-phase omits the √3 factor and uses line-to-neutral voltage in most cases.