Pahū ʻo Shenhai
ʻO ka wela wela kiʻekiʻe loa o nā ʻāpana e hoʻopili i nā hui ʻana o ke kinoea-ea i hoʻonui ʻia i nā lako uila palekana he mea koʻikoʻi ia i ka hoʻoholo ʻana i ka palekana pahū o nā mea uila.. Nā mea lawe o kēia manawa, ʻoi aku ka mana e like me nā wili a me nā mea hoʻomehana, hana e like me nā kumu wela i nā mea uila.
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 lako uila pahū, 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 “paepae” for ensuring the explosion-proof safety performance of hoʻonui i ka palekana electrical products. If the maximum heating temperature exceeds the limit temperature, it could ignite the corresponding pahū gas-air mixture or damage the mechanical and electrical properties of the materials used. ʻo kahi laʻana, 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. ʻo kahi laʻana, 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 hoʻonui i nā lako uila palekana, 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.