Hermetically Sealed Treansformer
The hermetically sealed oil transformers are normally manufactured with a sealed tank equipped with fins that allow the expansion at the temperature variations. The tightness of the tank is up to 0.5 Bar. This type of transformer is the most widely used in the world. In the hermetically sealed transformer, the oil does not come into contact with the air and its electrical properties are therefore not compromised, ensuring a long life span of the transformer. For powers exceeding 3150kVA, or in case of a transformer with radiators, the transformer can still be hermetically sealed by means of a nitrogen cushion.
| Power | 50 kVA – 5MVA |
| Voltage Class | 1.1kV – 52kV |
| Material temperature classes | A , F |
| Environmental temperature | -60 a + 60 |
| winding materials | aluminium or copper |
| Oil | Mineral, silicone, ester or vegetable type |
| Accessories | Overpressure valve, thermometer, oil level, anti-vibration device, protective boxes |
| Strengths | outdoor installation even with aggressive environmental conditions; compact size for high voltages, excellent resistance to over voltages in resonance |