Three Phase Heater Current Calculation

Three-Phase Current Formula:

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

Current (I):

amps

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Three 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 three-phase heating systems.

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)
\( V \) — Line voltage (volts)
\( PF \) — Power factor (unitless, typically 1.0 for resistive 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, circuit protection, and prevents overheating in electrical systems.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Why is power factor 1.0 for heaters?
A: Electric heaters are purely resistive loads, so voltage and current are in phase (PF = 1.0).

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

Q3: Does this work for non-heater loads?
A: Yes, but for inductive loads (motors, etc.) use the appropriate power factor (typically 0.8-0.9).

Q4: Why divide by √3?
A: In three-phase systems, √3 relates line-to-line voltage to phase current in balanced loads.

Q5: How do I find the heater power rating?
A: Check the heater nameplate or specifications, usually given in kW or watts (1 kW = 1000W).