[BUG] Incident energy equation produces astronomically wrong values (10^28 instead of ~10-50 cal/cm²)

[sramharack]

Description

The incident energy calculation produces values like 10^28 J/cm² instead of expected values around 10-50 cal/cm².

Expected Behavior

For 30 kA bolted fault at 13.8 kV with HCB config:

• Per J.C. Das Table 3.9: ~12.7 cal/cm² at 100ms

Actual Behavior

result = calculate_arc_flash(ibf_ka=30.0, voc_kv=13.8, ...)
print(result.incident_energy_cal_cm2)
# Output: 8640976556685359089492951040.00 cal/cm²

Root Cause Analysis

The polynomial structure in _build_energy_exponent() adds ~29 to the exponent:

• k10 ≈ 0.97
• k10 × Ibf = 0.97 × 30 = 29.1

This 29 gets added to the exponent, causing 10^29 multiplier.

Tasks

• Open IEEE 1584-2018 Section 4.6, Equations (3)-(6)
• Verify exact polynomial structure
• Determine if k10 multiplies Ibf or is constant term
• Fix _build_energy_exponent() in incident_energy.py
• Fix _build_afb_numerator() in arc_flash_boundary.py
• Validate against Annex D examples

Files to Modify

• arc_flash_studio/calculations/incident_energy.py (line ~45)
• arc_flash_studio/calculations/arc_flash_boundary.py (line ~45)

Reference

IEEE 1584-2018, Section 4.6, Equations (3)-(6)