The temperature range of a dry-type transformer mainly depends on its insulation class - which determines the maximum temperature the transformer's windings and insulation can safely handle.
Here's a typical breakdown:
| Insulation Class | Maximum Hot Spot Temperature | Typical Ambient Temperature |
|---|---|---|
| Class A | 105°C | 30–40°C |
| Class B | 130°C | 30–40°C |
| Class F | 155°C | 30–40°C |
| Class H | 180°C | 30–40°C |
Normal operating ambient temperature is usually up to 40°C.
Rise limits over ambient temperature are typically:
Class A: 60°C rise
Class B: 80°C rise
Class F: 100°C rise
Class H: 125°C rise
So, for example, a Class F dry-type transformer can have a maximum winding temperature around 155°C (ambient 40°C + temperature rise 100°C + margin).
🔹 Summary:
Ambient operating range: typically -20°C to +40°C.
Internal winding temperatures: can safely reach 105°C to 180°C, depending on insulation class.
