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Overview:
Three-phase dry-type transformers are power transformers that do not use liquid insulating media (such as oil), providing a safe and environmentally friendly alternative to oil-immersed transformers. Dry-type transformers use air or solid materials (such as epoxy resin) instead of oil. This design greatly limits the risk of oil leakage and fire, making them ideal for indoor installation in commercial, residential and industrial environments. Dry-type transformers have high reliability, low maintenance requirements and adaptability to various environments. They are increasingly favored by sustainable applications and occupy an important position in modern power systems.
Basic structure and working principle:
Core structure composition
Core: Made of high magnetic permeability silicon steel sheets to minimize eddy current losses and ensure efficient magnetic flux transfer.
Winding: High-voltage and low-voltage windings are encapsulated with epoxy resin or other solid insulating materials to enhance durability and resistance to environmental factors. Aluminum or copper conductors are usually used.
Cooling system: Rely on natural convection (AN) or forced air cooling (AF) through fans.Natural air cooling (AN): relies on natural convection of air to dissipate heat, with a simple structure and low noise. Forced air cooling (AF): Accelerates air flow through the built-in fan, improves heat dissipation efficiency, and allows short-term overload operation.Some designs use heat-resistant materials to control heat.
Protective housing: Rugged housing made of stainless steel or coated metal protects internal components from dust, moisture and mechanical damage.
Working principle:
The core working principle of dry-type transformers is based on Faraday's law of electromagnetic induction. When alternating current passes through the primary winding (primary coil) of the transformer, an alternating magnetic flux is generated in the iron core, which in turn induces an electromotive force (voltage) in the secondary winding (secondary coil). By adjusting the turns ratio of the primary winding to the secondary winding, the voltage can be increased (boosted) or decreased (stepped down).
Main technical features:
Fireproof: Equipped with high-quality insulation materials to eliminate fire hazards, it is very suitable for commercial centers or environments with high traffic.
Low maintenance: No oil testing or leakage monitoring is required, which reduces operating costs.
Environmental adaptability: Resistant to moisture, dust and chemicals, suitable for a variety of harsh conditions.
Energy efficiency: Advanced design can achieve up to 98% efficiency and low no-load losses.
Compact design: Lightweight and space-saving, it is very suitable for installation in space-constrained environments.
Structural forms of dry-type transformers:
1. Open type: It is a commonly used form. Its body is in direct contact with the atmosphere. It is suitable for places with relatively high humidity and temperature standards. Generally, there are two cooling methods: air self-cooling and wind cooling.
2. Closed type: The body is in a closed shell and is not in direct contact with the atmosphere. The heat dissipation conditions are poor. It is mainly used in mining and belongs to explosion-proof type).
3. Casting type: Epoxy resin or other resin casting is used as the main insulation. It has a simple structure and small size. It is suitable for transformers with smaller capacity.
Selection of dry type transformer:
1.Load type
Conventional loads (such as commercial buildings and factories): Standard distribution dry-type transformers are preferred.
Special loads (such as inverters, rectifier equipment, and new energy grid connection): Harmonic suppression or high overload capacity transformers need to be customized.
Impact loads (such as arc furnaces and cranes): Select models with strong short-circuit tolerance and reserve capacity redundancy.
2.Installation environment
Indoor/enclosed space: Ventilation conditions need to be considered, open (AN/AF) or closed (CST) design.
Outdoor/harsh environment (high humidity, salt spray, dust): IP55 protection level, epoxy resin cast windings, and anti-condensation heaters are selected.
Flammable and explosive areas (such as mines and chemical plants): Select explosion-proof certified models (such as Ex d IIB T4).
Future development of dry-type transformers:
High efficiency and energy saving and application of new materials
1.Popularization of amorphous alloy cores
The no-load loss of amorphous alloy dry-type transformers is 60%~80% lower than that of traditional silicon steel sheets. In the future, as the cost of amorphous materials decreases, the market share will increase significantly.
2.Exploration of superconducting materials
High-temperature superconducting (HTS) windings can transmit electricity with almost zero resistance. They are currently in the laboratory stage, and commercialization requires breaking through the bottleneck of low-temperature cooling systems.
3.Environmentally friendly insulating materials
Bio-based epoxy resins, silicone rubber and other degradable materials replace traditional resins to reduce carbon footprints.
Halogen-free flame retardant materials (such as ceramic silicone rubber) meet strict environmental regulations such as EU RoHS 3.0.
Conclusion
Three-phase dry-type transformers are essential to advancing safe, sustainable and smart grids. Facing future opportunities and challenges, Lugao Power Co., Ltd. continues to innovate and improve its manufacturing technology. It is committed to meeting the power distribution requirements of customers around the world and creating cutting-edge dry-type transformers that serve the future smart grid. Choose LUGAO to protect your power distribution project.
