Torque Equation of DC Series Motor

Torque Formula:

\[ T = K_t \times I^2 \times \Phi \]

Torque (T): lb-ft

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1. What is the Torque Equation of DC Series Motor?

Definition: This equation calculates the torque produced by a DC series motor based on the torque constant, current squared, and magnetic flux.

Purpose: It helps electrical engineers and motor designers understand and predict the torque characteristics of DC series motors.

2. How Does the Equation Work?

The equation is:

\[ T = K_t \times I^2 \times \Phi \]

Where:

\( T \) — Torque (lb-ft)
\( K_t \) — Torque constant (lb-ft/A·Wb)
\( I \) — Current (amps)
\( \Phi \) — Magnetic flux (Wb)

Explanation: In a series motor, torque is proportional to the square of the current because both armature and field current are the same.

3. Importance of Torque Calculation

Details: Accurate torque calculation is essential for motor selection, performance prediction, and mechanical design of motor-driven systems.

4. Using the Calculator

Tips: Enter the torque constant (default 0.05 lb-ft/A·Wb), current in amps, and magnetic flux (default 0.8 Wb). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is current squared in the equation?
A: In series motors, the same current flows through both armature and field windings, making torque proportional to I².

Q2: What's a typical torque constant value?
A: This varies by motor design but often ranges from 0.01 to 0.1 lb-ft/A·Wb for industrial DC series motors.

Q3: How does flux affect torque?
A: Higher magnetic flux increases torque proportionally, but saturation limits the maximum achievable flux.

Q4: Is this equation valid for all DC motors?
A: No, this specific form applies only to series-wound DC motors. Shunt motors have a different torque equation.

Q5: How does temperature affect the calculation?
A: Temperature changes can affect resistance and magnetic properties, which may require adjustments to the input values.