Power Calculator Electrical Circuit

Power Formula:

\[ P = V \times I \times PF \]

For three-phase circuits, multiply by \( \sqrt{3} \) (approximately 1.732)

Voltage (V):

volts (V)

Current (I):

amperes (A)

Power Factor (PF):

(0 to 1)

Phase:

Power (P):

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1. What is Electrical Power?

Electrical power is the rate at which electrical energy is transferred by an electric circuit. In AC circuits, the actual power consumed depends on both the voltage/current and the power factor which represents phase difference between them.

2. How Does the Calculator Work?

The calculator uses the power formula:

\[ P = V \times I \times PF \]

For three-phase systems, the formula becomes:

\[ P = \sqrt{3} \times V \times I \times PF \]

Where:

\( P \) — Power in watts (W)
\( V \) — Voltage in volts (V)
\( I \) — Current in amperes (A)
\( PF \) — Power factor (unitless, 0 to 1)
\( \sqrt{3} \) — Approximately 1.732 (three-phase multiplier)

Explanation: The power factor accounts for the phase difference between voltage and current in AC circuits. A PF of 1 indicates all power is real power (resistive load), while lower values indicate reactive power (inductive or capacitive loads).

3. Importance of Power Calculation

Details: Accurate power calculation is essential for circuit design, load balancing, energy efficiency analysis, and proper sizing of electrical components like wires, breakers, and transformers.

4. Using the Calculator

Tips:

For single-phase circuits, select "Single-phase"
For three-phase circuits, select "Three-phase"
Power factor is typically between 0.8 and 1 for most equipment
For purely resistive loads (like heaters), use PF = 1

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between real, reactive, and apparent power?
A: Real power (W) does actual work, reactive power (VAR) sustains electromagnetic fields, and apparent power (VA) is the vector sum of both. This calculator gives real power.

Q2: How do I measure power factor?
A: Power factor can be measured with a power meter or calculated as the ratio of real power (W) to apparent power (VA).

Q3: Why is three-phase power multiplied by √3?
A: In balanced three-phase systems, the √3 accounts for the phase difference (120°) between the three voltage waveforms.

Q4: Can I use this for DC circuits?
A: Yes, for DC set PF=1 and select single-phase (DC has no phase or power factor considerations).

Q5: What's a typical power factor for motors?
A: Induction motors typically have PF between 0.7-0.9 at full load, lower when lightly loaded.