No flammable medium, high fire rating
Dry type transformers use air (self cooling) or inert gas (such as SF ₆, gas insulated) as the cooling medium, and the winding insulation material is mostly flame-retardant epoxy resin (Class F/H). Even under extreme working conditions such as overload and short circuit, it will not produce flammable steam or leak flammable liquids, and does not have fire propagation.
Compared to oil immersed transformers: The insulation oil of oil immersed transformers has a flash point of about 135 ℃, is prone to combustion at high temperatures, and the flame will spread with the oil flow; The flame-retardant insulation material of dry-type transformers can withstand high temperatures of 155 ℃ (F level) or 180 ℃ (H level), and will only carbonize in the event of fire without aiding combustion. The fire resistance level can reach IP20 or above, and can be directly installed inside buildings (such as distribution rooms and floor distribution rooms).
No explosion risk, safer to use
If an internal short circuit occurs in an oil immersed transformer, the insulating oil will decompose at high temperatures and produce a large amount of gas, which may cause the oil tank to explode; The windings and iron cores of dry-type transformers are exposed to air (or sealed in gas insulated shells), with no risk of pressure accumulation. Even if a fault occurs, it only manifests as overheating of the windings and tripping of the protection device, without causing an explosion. It is especially suitable for densely populated places such as shopping malls, hospitals, subways, and data centers.
