谐波滤波器计算器
使用此谐波滤波器计算器快速获得准确的计算结果。
3-5 for enclosed, 5-8 for open air
For temperature, grouping, etc.
Derated Ampacity
24.0 A
Derated Ampacity vs Conductor Cross Section
公式
## Cable Ampacity Estimation Ampacity is the maximum continuous current a conductor can carry without exceeding its temperature rating. ### Formula **Ampacity = Cross Section x Current Density x Derating Factor** ### Current Density Guidelines - Open air: 5-8 A/mm^2 - In conduit: 3-5 A/mm^2 - Underground: 2-4 A/mm^2 ### Derating Factors - Ambient temperature above 30 C: 0.7-0.9 - Multiple cables in conduit: 0.5-0.8 - Direct burial: 0.7-0.85 Always verify with NEC/IEC tables for your specific installation.
计算示例
6 mm^2 copper cable, 5 A/mm^2, derating 0.8, at 230 V.
- 01Base ampacity: 6 x 5 = 30 A
- 02Derated: 30 x 0.8 = 24 A
- 03Max power: 24 x 230 = 5,520 W = 5.52 kW
常见问题
Is this a substitute for NEC/IEC tables?
No. This provides estimates. Always use the applicable electrical code tables for final cable sizing in real installations.
What happens if I exceed ampacity?
The cable overheats, insulation degrades, and eventually a fire hazard develops. Overcurrent protection (breakers/fuses) should prevent this.
How does cable length affect sizing?
Longer cables have more resistance, causing voltage drop. You may need to upsize the cable beyond ampacity requirements to limit voltage drop.
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