After magnesium oxide refilling, hot-state testing can only be performed after sintering, cooling to room temperature, and equipment assembly, followed by 30 minutes of power-on operation. The entire process, starting from sintering, typically takes 4–6 hours.
Hot-State Testing Timeline and Conditions
|
Stage |
Time |
Key Requirements |
|
Sintering and Holding |
1–2 hours |
Ensure sufficient recrystallization of grains at 800–1000℃ |
|
Natural Cooling in Furnace |
1–2 hours |
Cool with the furnace to <200℃ to prevent thermal stress cracking |
|
Cooling to Room Temperature After Removal from Furnace |
30–60 minutes |
Ensure component temperature stabilizes at approximately 25℃ |
|
Installation and Cold-State Testing |
30 minutes |
Complete assembly and pass cold-state insulation resistance (≥500 MΩ) and withstand voltage tests |
|
Power-On Operation |
30 minutes |
Apply rated power to bring the heating element to normal operating temperature |
The hot-state test should complete the insulation resistance measurement within 2 seconds after power-off, with a standard of ≥200 MΩ, to verify the stability of insulation performance at high temperatures.
Precautions: A cold-state test must be performed to confirm there is no risk of short circuit or breakdown before powering on; During operation, monitor the current and temperature rise curves to ensure there are no abnormal fluctuations; The ambient humidity should be ≤30% to avoid surface leakage affecting the readings.
Starting operation without sufficient cooling may lead to uneven internal stress release, causing microcracks or premature failure.
