Half-Cycle and Full-Cycle Surge Current Rating
Half-Cycle Surge Current Rating
Refers to the maximum surge current a device can withstand for one half of an AC waveform.
- Duration: ~8.3 ms (60 Hz) or 10 ms (50 Hz)
- Also called non-repetitive peak surge current
Example: If a diode has a half-cycle surge rating of 100 A,
it can survive a single short spike of 100 A for one half-cycle.
Full-Cycle Surge Current Rating
Refers to the surge current the device can handle over a complete AC cycle (positive and negative halves).
- Duration: ~16.7 ms (60 Hz) or 20 ms (50 Hz)
- Allowable current is usually lower due to higher energy
Key Differences
| Feature | Half-Cycle | Full-Cycle |
|---|---|---|
| Duration | Half waveform | Full waveform |
| Time (50 Hz) | ~10 ms | ~20 ms |
| Current Rating | Higher | Lower |
| Stress on Device | Less energy | More energy |
Why This Matters
These ratings are important for understanding how components behave under transient conditions such as:
- Inrush current (when power is first applied)
- Lightning or switching surges
- Fault conditions