Calculate AC Voltage Drop

AC Voltage Drop Formula:

\[ V_{drop} = \sqrt{3} \times I \times (R \cos \varphi + X \sin \varphi) \times L \]

Current (I):

Amps

Resistance (R):

Ω/km

Power Factor (cos φ):

(0-1)

Reactance (X):

Ω/km

Length (L):

Voltage Drop (V_drop):

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1. What is AC Voltage Drop?

AC voltage drop refers to the reduction in voltage that occurs when electrical current flows through a conductor in an alternating current (AC) system. This drop is caused by the resistance and reactance of the conductor and is an important consideration in electrical system design.

2. How Does the Calculator Work?

The calculator uses the three-phase AC voltage drop formula:

\[ V_{drop} = \sqrt{3} \times I \times (R \cos \varphi + X \sin \varphi) \times L \]

Where:

\( V_{drop} \) — Voltage drop in volts (V)
\( \sqrt{3} \) — Constant for three-phase systems (1.732)
\( I \) — Current in amperes (A)
\( R \) — Resistance in ohms per kilometer (Ω/km)
\( \cos \varphi \) — Power factor
\( X \) — Reactance in ohms per kilometer (Ω/km)
\( L \) — Length of conductor in kilometers (km)

Explanation: The formula accounts for both resistive and reactive components of impedance in AC systems, with the power factor determining the phase relationship between voltage and current.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures that electrical equipment receives adequate voltage for proper operation, prevents overheating of conductors, and maintains system efficiency and safety.

4. Using the Calculator

Tips: Enter current in amps, resistance and reactance in Ω/km, power factor between 0-1, and length in kilometers. All values must be positive, with power factor between 0 and 1 inclusive.

5. Frequently Asked Questions (FAQ)

Q1: What is the acceptable voltage drop percentage?
A: Typically, voltage drop should not exceed 3% for feeders and 5% for branch circuits in most electrical codes.

Q2: How does power factor affect voltage drop?
A: Lower power factors increase voltage drop due to higher reactive power component in the system.

Q3: What is the difference between single-phase and three-phase voltage drop?
A: Three-phase uses √3 factor and generally has lower voltage drop for the same power transmission compared to single-phase.

Q4: How does conductor material affect voltage drop?
A: Different materials (copper, aluminum) have different resistivity values, affecting the resistance (R) component of the calculation.

Q5: When is voltage drop calculation critical?
A: Critical for long cable runs, high current applications, sensitive electronic equipment, and when designing energy-efficient systems.