申海防爆
增安型电气设备中可能接触可燃气体-空气混合物的部件的最高加热温度是决定电气设备防爆安全性的关键因素. 载流元件, 特别是绕组和加热元件等功率元件, 作为电气设备的热源.
The maximum heating temperature should not exceed the limit temperature of increased safety electrical devices. The term ‘limit temperature’ refers to the highest permissible temperature of 防爆电气设备, which is the lower of the temperature determined by the equipment’s temperature class and the temperature at which the materials used achieve thermal stability. This limit temperature is the “临界点” for ensuring the explosion-proof safety performance of 提高安全性 electrical products. If the maximum heating temperature exceeds the limit temperature, it could ignite the corresponding 爆炸物 gas-air mixture or damage the mechanical and electrical properties of the materials used. 例如, for insulated windings, a sustained temperature beyond the stability temperature can halve its lifespan for every 8-10°C increase.
For insulated windings, their maximum heating temperature must not exceed the standard stipulated in the table.
Limit Temperature of Insulated Windings
| Characteristic Items | Temperature Measurement Method | Heat Resistance Level Of Insulation Materials | ||||
|---|---|---|---|---|---|---|
| - | - | A（105℃） | E（120℃） | B（130℃） | F（155℃） | H（180℃） |
| Maximum Temperature During Rated Operation/℃ | ||||||
| Single Layer Insulated Winding | Resistance Method Or Thermometer Method | 95 | 110 | 120 | 130 | 155 |
| Other Insulated Windings | Resistance Method | 90 | 105 | 110 | 130 | 155 |
| Other Insulated Windings | Thermometer Method | 80 | 95 | 100 | 115 | 135 |
| Extreme Temperature During Stall/℃ | ||||||
| Extreme Temperature At The End Of TE Time | Resistance Method | 160 | 175 | 185 | 210 | 235 |
For conductors carrying electrical current, at the maximum heating temperature, the material’s mechanical strength should not be reduced, there should be no deformation beyond what the permissible stress allows, and adjacent insulation materials should not be damaged. 例如, in the case of increased safety three-phase asynchronous motors, the rotor’s heating temperature will not harm the insulation of the stator windings.
In the design of 提高电气设备的安全性, to prevent certain components’ temperatures from exceeding their limit temperature, designers should consider incorporating appropriate temperature protection devices, in addition to the electrical and thermal performance of the electrical components, to prevent overheating beyond their limit temperature.