Transformer Cable Size Calculator

Transformer Cable Size Formula:

\[ \text{Size (mm}^2\text{)} = \frac{I \times \text{distance} \times k}{VD} \]

Current (I):

Distance:

Constant (k):

Voltage Drop (VD):

Cable Size:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Transformer Cable Size Formula?

The transformer cable size formula calculates the appropriate cross-sectional area of electrical cable needed for transformer installations based on current, distance, material constant, and acceptable voltage drop.

2. How Does the Calculator Work?

The calculator uses the cable size formula:

\[ \text{Size (mm}^2\text{)} = \frac{I \times \text{distance} \times k}{VD} \]

Where:

\( I \) — Current in amperes (A)
\( \text{distance} \) — Cable length in meters (m)
\( k \) — Material constant (depends on conductor material and temperature)
\( VD \) — Acceptable voltage drop in volts (V)

Explanation: The formula ensures that the selected cable size minimizes voltage drop while safely carrying the required current over the specified distance.

3. Importance of Cable Size Calculation

Details: Proper cable sizing is crucial for electrical safety, preventing overheating, minimizing energy losses, and ensuring optimal performance of transformer systems.

4. Using the Calculator

Tips: Enter current in amperes, distance in meters, material constant value, and acceptable voltage drop in volts. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical value of constant k?
A: For copper conductors at 75°C, k is approximately 0.021. For aluminum, it's about 0.034. Always consult relevant standards for specific applications.

Q2: What is an acceptable voltage drop?
A: Generally, voltage drop should not exceed 3% for power circuits and 5% for lighting circuits from supply point to load.

Q3: Why is cable size important for transformers?
A: Proper cable sizing ensures efficient power transfer, prevents overheating, reduces energy losses, and maintains voltage stability.

Q4: Does ambient temperature affect cable sizing?
A: Yes, higher ambient temperatures require larger cable sizes to maintain safe operating temperatures and current carrying capacity.

Q5: Should derating factors be considered?
A: Yes, factors like cable grouping, installation method, and ambient temperature may require applying derating factors to the calculated size.