Altitude Test Chamber compressor overload and low pressure alarm maintenance

In the Altitude Test Chamber composite fault repair cases, the technical team through the three-level diagnostic method to accurately locate the PLC hardware failure and mechanical seal failure two core issues. The trouble shooting process of this Altitude Test Chamber provides a systematic maintenance reference for the industry:

 
I. Failure phenomenon and diagnostic logic

A model of Altitude Test Chamber in the simulation of 15.2km altitude conditions, the compressor overload alarm and low pressure alarm triggered at the same time. The technical team used "refrigerant system → operation logic → electrical control → sealing system" four-step investigation method:

1. Refrigerant system verification: measured dual compressor equilibrium pressure stabilized at 150PSI, to rule out the possibility of Altitude Test Chamber refrigerant leakage;

2. Operation logic abnormalities: found that only the C2 compressor to participate in the control of temperature, C1 continues to dissipate the heat for the C2 resulting in low-pressure alarms;

3. PLC hardware failure: Detection of PLC output module no signal, confirm the Altitude Test Chamber control circuit relay aging damage;

4. Sealing system failure: motor fixation block screws loose, door latch slack leads to box leakage.

 
II. The systematic solution for Altitude Test Chamber compound failure to implement double transformation:

control circuit upgrade

• Add 25 seconds delay relay to achieve the C2 compressor sequential start;
• After the transformation of the test shows that the contactor three-phase voltage back to normal values (380V ± 5%).

Mechanical seal reinforcement

• Use torque wrench to tighten the motor fixing block screws to 25N-m;
• Adjust the door latch compression mechanism, seal compression up to 30% of the original thickness.

III. The effectiveness of maintenance verification of Altitude Test Chamber repaired through the harsh test:

• High temperature test: 60 ℃ under the conditions of the temperature rise rate of 3 ℃ / min;
• Low-temperature test: -10 ℃ conditions with the simulation of the altitude of 15.2km, 15 minutes to complete the temperature and pressure dual-parameter stabilization;
• Seal Sealing performance: the leakage rate of the box is reduced to 0.05mbar-L/s (better than the original 0.1mbar-L/s standard).

IV. The daily maintenance recommendations to protect the long-term stable operation of the Altitude Test Chamber, you need to focus on:

• Compressor system: monthly check the oil level (to maintain the visual window more than 3/4), quarterly detection of the start-up current (fluctuations in the value of <10%);
• Electrical components: the annual replacement of PLC output module relays, every 500 hours Clean the contactor contacts;
• Sealing system: weekly inspection of the door seal compression status, quarterly correction of locking force (recommended value of 8-10kgf);
• Environmental adaptation: it is recommended to run the Altitude Test Chamber at an ambient temperature of 25 ± 3 ℃, the relative humidity of ≤ 70% RH.

The case reveals the typical characteristics of compound failure of Altitude Test Chamber: more than 80% of the failure originates from the coupling failure of control system and mechanical structure. The technical team recommends the establishment of a three-dimensional prevention mechanism - daily operating parameters comparison, monthly vibration spectrum analysis, semi-annual sealing performance verification, which can reduce the risk of unplanned downtime by more than 60%.