Input Parameters
About This Calculator
- R_ref = R_meas × 2^((T_meas - T_ref)/10)
- Min IR = kV rating + 1 MΩ (IEEE 43)
- Insulation resistance halves per 10°C rise
How this insulation resistance calculator works
Insulation resistance decreases with temperature. The correction formula: R_ref = R_measured × 2^((T_measured - T_ref)/10).
The IEEE 43 standard minimum: equipment voltage (kV) + 1 MΩ. For a 480V motor, minimum = 1.48 MΩ.
FAQ
What is IR testing?
Megger test measures insulation quality with high DC voltage.
Temperature correction?
R doubles for every 10°C drop. Corrected to 20°C reference.
kV+1 rule?
Min IR = kV rating + 1. 480V equipment needs ≥1.48 MΩ.