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An Overview of Main Dry-Type Transformer Series: SCB11–SCB18, Non-Encapsulated Class H, and On-Load Tap-Changing Dry-Type Transformers—How to Choose
Thanks to their fire-resistant and flame-retardant properties, maintenance-free operation, and ability to be installed at load centers, dry-type transformers are widely used in high-rise buildings, subways, mines, chemical plants, hospitals, commercial complexes, and other facilities. The market offers numerous models, including SCB series resin‑cast, SG(B) non‑encapsulated Class H, SCZB on‑load tap‑changing, and amorphous alloy dry‑type transformers, which can easily confuse buyers regarding product differences.
SCB11–SCB18 resin‑insulated dry‑type transformers are the most commonly used models for building power distribution in China. Featuring foil‑wound windings and epoxy resin casting, they offer excellent moisture resistance and can operate even in 100% relative humidity environments. With forced air cooling, they can overload up to 150% of their rated capacity. The higher the SCB number, the greater the energy efficiency class; SCB18 represents the current mainstream first‑class energy‑efficiency model.
SG (B) 11‑18 non‑encapsulated Class H dry-type transformers, manufactured using the German MORA process. The windings are not resin‑impregnated, and the Class H insulation provides excellent high‑temperature resistance, fire protection, and water resistance. These transformers are well suited for applications with stringent fire‑safety requirements, such as subways, ships, mines, and chemical plants. A drawback is their higher cost compared to standard cast‑resin dry‑type transformers; therefore, a comprehensive assessment against the project budget is recommended.
The SCZB series on-load tap-changing dry-type transformers can adjust output voltage under load, making them suitable for grid areas with significant voltage fluctuations, such as new energy integration points and large industrial facilities. They stabilize secondary-side voltage without requiring power outages. The SC(B)H15 amorphous alloy dry-type transformer’s key advantage is its extremely low no-load loss, making it ideal for commercial buildings and campus distribution systems with low load factors and prolonged light-load operation.
Key selection criteria include fire safety rating, site ambient temperature and humidity, load fluctuation magnitude, energy efficiency policy requirements, and whether on-load voltage regulation is needed. For buildings with high occupant density, prioritize SCB14 or higher‑efficiency cast resin dry-type transformers; for flammable or explosive environments and underground spaces, consider non‑encapsulated Class H or amorphous alloy dry-type transformers.
Shenyang Guangchangyun Power Equipment possesses full‑range design and manufacturing capabilities for dry‑type transformers, offering customizable models rated at 20 kV and 35 kV. It also provides integrated services, including switchgear, power construction, and electrical design, delivering comprehensive dry‑type transformer solutions for various public buildings, industrial facilities, and new energy projects.
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