1. What is Transformer Winding Resistance?

Transformer winding resistance is the DC resistance of the copper or aluminum windings in a transformer. It's a critical parameter that affects transformer performance, efficiency, and heat generation.

2. How Does the Calculator Work?

The calculator uses Ohm's Law:

Where:

• \( R \) — Winding resistance (ohms)
• \( V \) — Voltage drop across winding (volts)
• \( I \) — Current through winding (amperes)

Explanation: The resistance is calculated by dividing the measured voltage drop by the applied DC current.

3. Importance of Winding Resistance Measurement

Details: Measuring winding resistance helps identify shorted turns, verify proper connections, calculate I²R losses, and determine transformer health. It's essential for transformer commissioning and maintenance.

4. Using the Calculator

Tips: Enter the measured voltage drop across the winding and the applied test current. Both values must be positive numbers. The test should be done with DC current at rated tap position.

5. Frequently Asked Questions (FAQ)

Q1: Why use DC current for measurement?
A: DC eliminates inductive reactance, allowing pure resistance measurement. AC would measure impedance instead of just resistance.

Q2: What are typical winding resistance values?
A: Values vary by transformer size but are typically very low (milliohms to a few ohms) for power transformers.

Q3: How does temperature affect measurements?
A: Resistance increases with temperature. Measurements should be temperature-corrected to a standard reference (usually 20°C or 75°C).

Q4: What equipment is needed for measurement?
A: A DC resistance tester or micro-ohmmeter that can supply sufficient current (typically 1-10% of rated current).

Q5: How often should winding resistance be measured?
A: During factory tests, after installation, and periodically during maintenance (annually or per manufacturer recommendations).