Классификация по температурным классам служит важнейшим показателем безопасности для оценки воспламеняемости горючих газов и взрывозащищенности электрооборудования. Flammable gases are categorized into six classes based on their combustion temperatures, while electrical equipment is classified into six categories based on their maximum surface temperatures, denoted as T1, T2, T3, T4, T5, and T6. However, the grouping criteria for electrical equipment and flammable gases are distinctly different.
| Температурный класс | Температура воспламенения горючего газа/°C | Максимальная температура поверхности оборудования T/°C |
|---|---|---|
| T1 | t≥450 | 450 ≥ t > 300 |
| T2 | 450＞t≥300 | 300 ≥ t > 200 |
| T3 | 300＞t≥200 | 200 ≥ t > 135 |
| T4 | 200＞t≥135 | 135 ≥ t > 100 |
| T5 | 135＞t≥100 | 100 ≥ t > 85 |
| T6 | 100＞t≥85 | 85≥t |
The principle behind electrical equipment’s temperature classification is that the highest surface temperature generated by the equipment should not ignite surrounding flammable gases. In other words, the equipment’s maximum surface temperature must not exceed the ignition temperature of the flammable gases.
It is important to note that the maximum surface temperature of explosion-proof electrical equipment refers to the highest temperature that can be reached on its surface or parts under normal working conditions and under the most adverse conditions approved. This temperature should be capable of igniting the surrounding explosive gas-air mixture.
Due to varying explosion-proof designs, the maximum surface temperature could refer to different parts of the equipment. It might be the temperature on the outer surface of the enclosure, as in the case of flameproof electrical equipment, or it could be the temperature on the external surface of the equipment casing or certain internal components, such as in increased safety or pressurized electrical equipment.
