Dry-type transformers operate without a liquid insulating medium – insulation is provided by air and solid materials such as epoxy resin. They are the first choice for applications with high fire-protection requirements or particularly sensitive environments. Dry-type transformers meet the high safety and environmental requirements of modern building regulations and are increasingly becoming the standard solution in buildings.
What types of dry-type transformers are there?
The main designs are cast-resin transformers, in which the windings are encapsulated in epoxy resin, and open dry-type transformers with air-cooled windings. Both variants operate without oil, but differ in fire and environmental protection class, compactness, and application range.
Key Characteristics at a Glance
- No insulating liquid – no oil changes, no containment basin
- Fire behavior class F1: self-extinguishing
- Environmental class E2: high resistance to moisture
- Climate class C2: usable at low temperatures
- Ratings up to 25 MVA and voltages up to 36 kV available
- Low maintenance effort over the entire service life
- High recyclability of all materials used
Frequently Asked Questions
When is a dry-type transformer the right choice?
Wherever the highest fire-protection and environmental requirements apply: high-rise buildings, hospitals, subways, tunnels, airports, data centers, and sensitive industrial facilities. Wind turbines also frequently rely on dry-type designs due to their low maintenance requirements.
Are there any disadvantages compared with oil-type transformers?
Dry-type transformers are often somewhat more expensive to purchase and less common at very high power ratings than oil-type units. Their cooling capacity is also more limited. However, these points are often significantly offset in a total cost comparison over the service life.
How does fire protection differ between dry-type and oil-type transformers?
Dry-type transformers require no containment basin and no elaborate fire-protection partitions, since no oil can leak or burn. For oil-type transformers, oil containment basins, fire-protection walls, and in some cases CO₂ extinguishing systems are structurally required – dry-type transformers save considerable effort here.
What maintenance recommendations exist specifically for dry-type transformers?
Recommended measures include regular visual inspection, cleaning the windings of dust and contamination, torque checking of connections, and thermographic examinations. Compared with oil-type transformers, maintenance effort is considerably lower – intervals of two to three years are usually sufficient.
For your application with elevated fire-protection or environmental requirements, we supply the right dry-type transformer. Talk to our experts.