How are Power Transformers Classified by Insulation and Cooling Medium?

Power transformers can be classified based on the insulation and cooling media of the winding, mainly including liquid-immersed, gas, and dry-type transformers.

1. Liquid-Immersed Transformers: Liquid-immersed transformers use insulating liquid to immerse the winding and the insulation outside the winding. This liquid serves as both the insulation medium and the cooling medium for the winding. Insulating liquids include transformer oil, polychlorinated biphenyl (PCB), silicon oil, beta oil, alpha oil, and composite insulation liquids.

(1) Oil-Immersed Transformers: Oil-immersed transformers use transformer oil as the insulation and cooling medium. Despite environmental concerns, transformer oil is still widely used due to its excellent performance and low cost.

(2) PCB-Insulated Transformers: Polychlorinated biphenyl (PCB) is used as a non-flammable or difficult-to-burn cooling and insulation medium. However, due to environmental issues, the use of PCB has been prohibited in many countries, although some transformers using PCB are still in operation.

(3) Silicon Oil-Filled Transformers: To address environmental concerns associated with PCB, silicon oil has been found as an alternative. Silicon oil is non-toxic, non-flammable, and thermally stable, but it has high viscosity, making impregnation difficult, and it can generate gas under high-voltage electric fields.

(4) Beta Oil-Insulated Transformers: Beta oil is an industrial standard flame-retardant insulating oil used for indoor equipment. It is derived from 100% hydrocarbon petroleum and serves as a non-flammable liquid insulation medium.

2.Gas Transformers: Gas transformers use gas as the insulation medium, with common gases being nitrogen and hydrogen sulfide.

3.Dry-Type Transformers: Dry-type transformers do not use liquid media; the winding and core are exposed directly to the air. They use air or gas as the insulation medium with certain moisture-resistant measures.

LuShan, est. 1975,  is a Chinese professional manufacturer specializing in power transformers and reactors for 49 years. Leading products are single-phase transformer, three-phase transformers, DC inductors, AC reactors, filtering reactor, expoxy resin high-voltage transformer and intermediate, high-frequency products. Our transformers and reactors are widely used in 10 application areas: rapid transit, construction machinery, renewable energy, intelligent manufacturing, medical equipment, coal mine explosion prevention , excitation system, vacuum sintering, central air conditioning.

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