Shenhai plahvatuskindel
Kergesti ohutus elektriseadmetes süttivate gaasi-õhu segudega kokku puutuda võivate komponentide maksimaalne kuumutamistemperatuur on elektriseadmete plahvatuskindla ohutuse määramisel kriitiline tegur. Voolu kandvad komponendid, eriti jõukomponendid nagu mähised ja kütteelemendid, toimivad elektriseadmetes soojusallikatena.
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 plahvatuskindlad elektriseadmed, 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 “künnis” for ensuring the explosion-proof safety performance of suurenenud ohutus electrical products. If the maximum heating temperature exceeds the limit temperature, it could ignite the corresponding plahvatusohtlik gas-air mixture or damage the mechanical and electrical properties of the materials used. Näiteks, 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. Näiteks, 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 suurenenud ohutus elektriseadmed, 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.