1. What is AC Loss in Roebel Cables?

AC loss in Roebel cables consists of hysteretic loss and coupling loss, calculated using H-formulation finite element methods (FEM) and critical state models for superconductor cables.

2. How Does the Calculator Work?

The calculator uses the AC loss formula:

Where:

• \( Hysteretic\ Loss \) — Loss due to magnetic hysteresis in superconductor
• \( Coupling\ Loss \) — Loss due to current coupling between strands
• \( Transport\ Current \) — Operating current in the cable (A)
• \( Frequency \) — AC frequency (Hz)
• \( Critical\ Current\ Density \) — Maximum current density before quenching (A/mm²)
• \( Number\ of\ Strands \) — Total strands in the Roebel cable

Explanation: The calculation incorporates critical state model principles and H-formulation FEM to accurately predict AC losses in superconducting Roebel cables.

3. Importance of AC Loss Calculation

Details: Accurate AC loss calculation is crucial for designing efficient superconducting power transmission systems, optimizing cooling requirements, and ensuring stable operation of high-temperature superconducting cables.

4. Using the Calculator

Tips: Enter transport current in amperes, frequency in hertz, operating temperature in kelvin, number of strands, and critical current density. All values must be positive and within reasonable operating ranges.

5. Frequently Asked Questions (FAQ)

Q1: What is the critical state model?
A: The critical state model describes how magnetic flux penetrates type-II superconductors and is fundamental for calculating hysteretic losses in AC applications.

Q2: Why use H-formulation FEM?
A: H-formulation finite element method provides accurate numerical solutions for electromagnetic problems in superconductors, handling complex geometries and non-linear material properties.

Q3: What factors affect coupling loss?
A: Coupling loss depends on strand twist pitch, contact resistance between strands, operating frequency, and cable geometry.

Q4: How does temperature affect AC loss?
A: Higher temperatures reduce critical current density, increasing both hysteretic and coupling losses while decreasing overall cable performance.

Q5: Are Roebel cables better than conventional designs?
A: Roebel cables offer reduced AC losses, better current distribution, and improved mechanical stability compared to conventional stranded superconducting cables.