I. Safety Check (First Step) In flammable and explosive environments, the system must be in a safe state before any testing.
1. Power Disconnection and Isolation: Strictly follow explosion-proof procedures to disconnect the power supply to the sensor and related circuits, and confirm that the intrinsically safe barrier is connected, ensuring the entire circuit is in a non-energized state.
2. Appearance and Sealing Inspection:
Housing: Carefully inspect the sensor housing for cracks, damage, or severe deformation. Any physical damage may compromise the explosion-proof performance.
Cable Entry: Check that the sealing ring is intact and free from aging and cracking, and that the cable is securely fixed, ensuring the integrity of the explosion-proof surface.
Marking: Confirm that the explosion-proof markings on the sensor (e.g., Ex ib I Mb) are clearly identifiable and within their validity period.
II. Performance Testing (Assessing Functional Status) After confirming safety, the following tests can be performed to evaluate the sensor's functionality.
1. Resistance Test (Preliminary Screening):
Method: Use a multimeter to measure the resistance between the sensor's signal output terminals.
Judgment: Compare the measured value with the nominal parameters in the sensor's technical manual. If the resistance difference is extremely large (e.g., infinite or close to zero), the internal circuitry may be open or short-circuited, and the sensor may be damaged.
2. Sensitivity and Output Test (Core Verification):
Method: Securely mount the sensor on a known, low-intensity vibration source (e.g., a small motor). Use an intrinsically safe signal conditioner or monitoring instrument to observe its output signal (e.g., mA value or voltage waveform).
Judgment:
Normal: The output signal should change smoothly with vibration, without obvious jumps, dead zones, or abnormal noise.
Abnormal: If the output signal does not change, fluctuates violently, deviates excessively from the theoretical value, or fails to return to zero after vibration stops, the sensor may be damaged or its performance severely degraded.
3. Repeatability Test (Auxiliary Judgment):
Method: Under the same vibration conditions, start and stop the vibration source multiple times, recording the sensor's output response each time.
Judgment: A well-performing sensor should have highly consistent output values. If repeatability is poor and the values fluctuate greatly, the sensor may be aging or damaged.
III. Comprehensive Judgment and Handling
Passing all tests: If the sensor's appearance is intact, safety parameters are qualified, and performance tests are normal, it can continue to be used.
Failing any test: If a safety inspection reveals damage to the explosion-proof structure, or if performance tests show abnormal functionality, the sensor should be stopped from use immediately.
Follow-up Actions: Do not attempt to disassemble or repair a damaged sensor yourself. Contact the supplier or a professional repair organization for handling and replacement of spare parts.
