1. What is DC Motor Resistance?

The DC motor resistance is the opposition to current flow in the motor windings, measured in ohms (Ω). It's a key parameter for understanding motor performance and diagnosing potential issues.

2. How Does the Calculator Work?

The calculator uses Ohm's Law:

Where:

• \( R \) — Resistance in ohms (Ω)
• \( V \) — Voltage across the motor (Volts)
• \( I \) — Current through the motor (Amps)

Explanation: The resistance is calculated by dividing the voltage measured across the motor by the current flowing through it.

3. Importance of Resistance Measurement

Details: Measuring motor resistance helps identify winding issues (shorts or opens), estimate power loss, and predict motor performance under different loads.

4. Using the Calculator

Tips:

• Measure voltage across motor terminals with a multimeter
• Measure current in series with the motor
• Ensure motor isn't rotating during measurement (locked rotor test)
• All values must be positive and greater than zero

5. Frequently Asked Questions (FAQ)

Q1: Why measure DC motor resistance?
A: Resistance measurement helps detect winding faults, estimate power loss, and verify motor specifications.

Q2: What are typical resistance values?
A: Small motors may have resistances from 1-100Ω, while large industrial motors can be in milliohms. Exact values depend on motor size and design.

Q3: How does temperature affect resistance?
A: Resistance increases with temperature (positive temperature coefficient). Measure at known temperature for accurate comparisons.

Q4: What if I get zero or infinite resistance?
A: Zero suggests a short circuit, infinite suggests an open circuit. Both indicate potential motor winding problems.

Q5: Is this the same as impedance?
A: No, resistance is the DC component. Impedance includes inductive reactance which varies with frequency in AC operation.