After magnesium oxide refilling, it must be sintered, cooled to room temperature, and undergo cold-state testing before being powered on for the first time. The entire process typically takes 3–5 hours. It is crucial to ensure that the insulation performance meets the standards to prevent breakdown or short circuits after power-on.
Key Processes Before First Power-On:
|
Stage |
Time |
Description |
|
Sintering & Holding |
1–2 hours |
Completes grain recrystallization at 800–1000℃, improving insulation density. |
|
Natural Cooling in Furnace |
1–2 hours |
Cools with the furnace to <200℃ to prevent thermal stress cracking. |
|
Cooling to Room Temperature After Removing from Furnace |
30–60 minutes |
Ensures the component temperature stabilizes at around 25℃. |
|
Cold-State Performance Testing |
Within 30 minutes |
Must pass insulation resistance (≥500 MΩ) and withstand voltage tests (AC 2000V, 1 minute without breakdown). |
The earliest possible power-on is 3 hours after the start of sintering, provided that all cooling and testing steps have been completed and the results are satisfactory.
Initial Power-On Operation Recommendations:
Low-Power Preheating Operation
For initial power-on, apply 50% of the rated voltage and run for 10–15 minutes, observing whether the temperature rise is stable.
Monitor for sudden changes in current, abnormal noises, or smoke.
Gradually Increase to Full Load
After confirming no abnormalities, increase to 100% power and run continuously for 30 minutes to enter the hot-state testing phase.
Real-Time Monitoring of Insulation Status
If the equipment is equipped with an online monitoring system, the trend of insulation resistance changes should be recorded to prevent the exposure of latent defects.
Powering on without passing the cold-state test or without sufficient cooling may lead to insulation breakdown, casing rupture, or fire risks; operation is strictly prohibited.
