How Does the Boost Function of the SC(B)18-2500/35 Dry-Type Transformer Work?

The SC(B)18-2500/35 dry-type transformer is not specifically manufactured as a “booster,” but it achieves bidirectional voltage conversion based on the principle of electromagnetic induction. Whether it performs a step-up function depends on the winding turns ratio design between the primary and secondary windings.

SC(B)18-2500/35 Model Analysis

The model code contains essential technical details:

SC(B): Three-phase epoxy resin cast dry-type transformer. “S” stands for three-phase, “C” refers to epoxy resin insulation, and “B” is a design performance indicator.
18: Represents design parameters such as efficiency level or loss index.
2500: Indicates the rated capacity of 2500kVA.
35: Shows the 35kV high-voltage rating. The direction of transformation (step-up or step-down) depends on the low-voltage side rating. For example, if the LV side is 10kV, the HV side functions as a step-up output to 35kV.

Working Principle of the Boost Function

The boost function is achieved through the winding turns ratio and electromagnetic induction:

Electromagnetic Induction: When AC flows through the primary winding, an alternating magnetic field is created in the core. This induces an electromotive force (EMF) in the secondary winding. If the secondary has more turns than the primary, the voltage is stepped up, expressed as E₂/E₁ = n₂/n₁.

Turns Ratio Design: For instance, if the low-voltage winding has 100 turns and the high-voltage side has 350 turns, the output voltage is ideally 3.5 times higher.
Insulation & Cooling: Epoxy resin provides electrical insulation and heat resistance, while natural air cooling (AN) or forced air cooling (AF) ensures stable performance under high-voltage step-up operation.

Step-Up Operation Process

1. Input Stage: The low-voltage side (e.g., 10kV) receives AC input, creating magnetic flux in the core.
2. Flux Transfer Stage: The alternating flux is transferred efficiently to the high-voltage winding via a three-phase core.
3. Boost Output Stage: With more winding turns on the HV side, a 35kV stepped-up voltage is induced and delivered.

Key Design Features

Winding Design: The high-voltage side adopts multi-layer segmented winding to improve insulation, while the low-voltage side uses foil or layered winding to reduce losses.
Insulation: Epoxy resin vacuum casting provides Class F or H insulation, with excellent resistance to moisture, aging, and short-circuits.
Cooling: Equipped with AN/AF dual cooling. Natural cooling is used for normal operation, while forced cooling increases overload capacity by 15–30%.
Voltage Regulation: A ±2×2.5% tap changer allows ±5% fine adjustment of the HV winding, ensuring stable voltage output under varying load or grid fluctuations.

Application of SC(B)18-2500/35 Step-Up Transformer

The SC(B)18-2500/35 dry-type transformer provides a reliable and safe step-up solution by combining electromagnetic induction with optimized winding design. Its dry-type insulation and cooling system make it highly suitable for indoor applications where fire safety and environmental protection are critical, such as subways, commercial centers, hospitals, and industrial plants. For safe operation, users should always follow the manufacturer’s nameplate specifications and operation guidelines.