Why Altitude Matters
Standard transformers are designed for installations up to 1000m above sea level. Above this altitude, lower air density reduces cooling efficiency and dielectric strength. This is particularly relevant for projects in Ethiopia (Addis Ababa at 2,355m), Kenya (Nairobi at 1,795m), and Andean regions.
Derating Factors
| Altitude (m) | Cooling Derating | Required Capacity Multiplier |
|---|---|---|
| 0–1000 | 0% (standard) | 1.00 |
| 1000–1500 | 2% | 1.02 |
| 1500–2000 | 4% | 1.04 |
| 2000–2500 | 6% | 1.06 |
| 2500–3000 | 9% | 1.10 |
| 3000–3500 | 12% | 1.14 |
| 3500–4000 | 15% | 1.18 |
| 4000–5000 | 20% | 1.25 |
How to Apply
Example: A 500kVA transformer needed at 2,500m altitude. Derating factor = 6%. Required kVA = 500 ÷ 0.94 = 532kVA. Select next standard size: 630kVA.
Additional Considerations
- Insulation: Increased creepage distances for reduced air dielectric strength
- Bushing Specifications: Extended creepage bushings (>25mm/kV for >2000m)
- Cooling: Forced air (AF) cooling recommended above 3000m
- Temperature Rise: Specially designed lower temperature rise limits
Always specify your installation altitude when requesting a quotation. Our engineering team will design transformers with appropriate clearances, insulation, and cooling for your specific site conditions.