Power Factor of 3 Phase Motor Calculator

Power Factor Formula:

\[ \text{Power Factor} = \frac{\text{Power (kW)}}{\sqrt{3} \times \text{Voltage (V)} \times \text{Current (A)} \times \text{Efficiency}} \]

Power:

Voltage:

Current:

Efficiency:

(0-1)

Power Factor:

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1. What is Power Factor?

Power factor is the ratio of real power (kW) to apparent power (kVA) in an AC electrical system. For 3-phase motors, it indicates how effectively electrical power is converted into useful mechanical work.

2. How Does the Calculator Work?

The calculator uses the power factor formula for 3-phase motors:

\[ \text{Power Factor} = \frac{\text{Power (kW)}}{\sqrt{3} \times \text{Voltage (V)} \times \text{Current (A)} \times \text{Efficiency}} \]

Where:

\( Power \) — Real power in kilowatts (kW)
\( Voltage \) — Line voltage in volts (V)
\( Current \) — Line current in amperes (A)
\( Efficiency \) — Motor efficiency (0 to 1)
\( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula calculates the ratio of actual power to the product of voltage, current, and efficiency, accounting for the 3-phase system characteristics.

3. Importance of Power Factor

Details: Power factor indicates how efficiently electrical power is being used. A low power factor (typically <0.85) means poor utilization of electrical power, which can lead to higher utility charges and require power factor correction.

4. Using the Calculator

Tips: Enter power in kW, voltage in volts, current in amps, and motor efficiency (typically 0.8-0.95 for most industrial motors). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a good power factor for motors?
A: Most 3-phase motors have a power factor between 0.85-0.95 at full load. Values below 0.85 typically indicate problems.

Q2: Why does power factor matter?
A: Utilities often charge penalties for low power factor. Improving power factor can reduce electricity costs and increase system capacity.

Q3: How can power factor be improved?
A: Common methods include adding power factor correction capacitors, using synchronous motors, or reducing motor idling time.

Q4: Does power factor change with load?
A: Yes, power factor is typically lowest at no-load and improves as the motor approaches full load.

Q5: What's the difference between leading and lagging power factor?
A: Lagging (most common) means current lags voltage (inductive load). Leading means current leads voltage (capacitive load).