AC And DC Voltage Drop Calculator

Voltage Drop Formulas:

\[ V_{drop} = 2 I R L \text{ (DC)} \] \[ V_{drop} = \sqrt{3} I (R \cos\varphi + X \sin\varphi) L \text{ (AC)} \]

System Type:

Current (I):

Resistance (R):

Ω/m

Length (L):

Voltage Drop (V_drop):

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1. What is Voltage Drop?

Voltage drop refers to the reduction in voltage in an electrical circuit between the source and load. It occurs due to the resistance and reactance in conductors and is an important consideration in electrical system design to ensure proper equipment operation.

2. How Does the Calculator Work?

The calculator uses voltage drop formulas for both DC and AC systems:

\[ V_{drop} = 2 I R L \text{ (DC)} \] \[ V_{drop} = \sqrt{3} I (R \cos\varphi + X \sin\varphi) L \text{ (AC)} \]

Where:

\( V_{drop} \) — Voltage drop (V)
\( I \) — Current (A)
\( R \) — Resistance per unit length (Ω/m)
\( L \) — Length of conductor (m)
\( X \) — Reactance per unit length (Ω/m) - AC only
\( \varphi \) — Phase angle (degrees) - AC only

Explanation: The DC formula accounts for the round-trip path (hence the factor of 2), while the AC formula includes both resistive and reactive components with power factor considerations.

3. Importance of Voltage Drop Calculation

Details: Proper voltage drop calculation ensures electrical equipment receives adequate voltage for optimal performance, prevents overheating of conductors, and complies with electrical codes and standards.

4. Using the Calculator

Tips: Select system type (DC or AC), enter current in amperes, resistance in ohms per meter, length in meters. For AC systems, also provide reactance and phase angle values. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the acceptable voltage drop percentage?
A: Typically 3-5% for branch circuits and 1-2% for feeder circuits, but consult local electrical codes for specific requirements.

Q2: Why is there a factor of 2 in the DC formula?
A: The factor of 2 accounts for the round-trip path of current flow (both positive and negative conductors in DC systems).

Q3: What is reactance in AC systems?
A: Reactance is the opposition to current flow due to inductance and capacitance in AC circuits, measured in ohms.

Q4: How does phase angle affect voltage drop?
A: Phase angle represents the power factor. Lower power factor (higher phase angle) generally increases voltage drop in AC systems.

Q5: When should I use this calculator?
A: Use for preliminary calculations in electrical design, cable sizing, and verifying compliance with voltage drop requirements.