What Is a Dry Type-Transformer?
Dry-type transformers are transformers that do not use insulating oil for cooling. Instead, they rely on air circulation around resin-coated coils for heat dissipation. This design offers several advantages, such as eliminating the risk of oil leaks and reducing environmental impact. However, they may not cool as effectively as oil-filled transformers and could require additional cooling equipment for larger capacities. Typically, dry-type transformers are more expensive than their oil-cooled counterparts.
Uses of Dry-Type Transformers
Dry-type transformers find applications in various settings:
1. Industrial Facilities and Factories
In industrial environments, they provide low-voltage power transmission to various equipment, offering safety advantages when installed indoors.
2. Commercial Facilities
They are widely used in shopping malls and other commercial buildings for powering lights, HVAC systems, elevators, etc., due to their low ignition risk.
3. Railroads
In railroad vehicles and systems, especially in enclosed spaces like subways, dry-type transformers offer enhanced safety and space-saving benefits.
Principle of Dry-Type Transformer
Dry-type transformers operate on the principle of electromagnetic induction, using two windings on an iron core to transform voltage. The heat generated during this process is dissipated via air cooling, contrasting with oil-filled transformers that use oil and cooling fins for heat dissipation.
Selecting a Dry-Type Transformer
Considerations for choosing a dry-type transformer include required capacity, voltage, and operating environment:
1. Required Capacity
Select a capacity that can handle average power usage efficiently, typically around 60% of the transformer’s capacity, while accommodating maximum power and inrush currents.
2. Voltage
Choose appropriate high and low-voltage sides, taking into account the specific requirements of the location and the load.
3. Operating Environment
Consider the installation location and environmental factors like humidity, temperature, and vibration to ensure the transformer’s suitability and durability.
Comparing Dry-Type and Molded Transformers
Dry-type transformers differ from molded transformers in cooling methods and protection performance. While dry-type transformers use varnish for winding protection and require external protection against physical damage and moisture, molded transformers encapsulate windings in insulating materials like epoxy resin for cooling and protection. This difference affects the manufacturing costs and applications of each transformer type.