In depth and accurate diagnosis of faults in vertical semi submersible long shaft deep well turbine pumps

The precise fault diagnosis of vertical semi submersible long shaft deep well turbine pumps can be achieved through a standardized process of "non dismantling layered investigation on the well+quantitative detection of dismantling entities". Without blindly starting and dismantling the pump, the specific fault point can be 100% locked:
Prioritize and troubleshoot from easy to difficult, covering over 80% of common faults in vertical semi submersible long shaft deep well turbine pumps
1. Electrical parameter verification: Use a multimeter to measure the three-phase voltage, confirm that the voltage is within the range of ± 5% of the rated value, and troubleshoot issues such as phase loss and low voltage; Measure the insulation resistance of a 380V motor with a megohmmeter, and if it is lower than 0.5M Ω, it is directly judged that the motor seal has failed and water has entered; Comparing the resistance of three-phase windings, if the resistance deviation exceeds 5%, it is determined that there is a short circuit fault in the winding.
2. Operating parameter mapping: Record real-time operating current. If the current exceeds the rated value and does not fall back even after the valve is closed, it directly points to bearing wear and impeller jamming faults; If the outlet pressure is more than 20% lower than the design value, it is determined that the impeller is worn and the water lifting pipe is leaking.
3. Vibration noise localization: Use a vibration meter to detect the vibration value of the pump seat. If the vibration is greater than 1.8mm/s and accompanied by low-frequency "rumbling" sound, determine the fault of shaft bending and impeller imbalance; Accompanied by high-frequency "squeaking" friction sound, it is determined that the bearing is dry worn and the shaft sleeve is worn.
4. External working condition verification: Check the current dynamic water level in the well. If the dynamic water level is lower than 1m from the suction port, it is determined that there is insufficient liquid intake; If the leakage rate of the shaft seal is greater than 5 drops per minute, it is determined that the packing/mechanical seal has worn out and failed.
After lifting out the vertical semi submersible long shaft deep well turbine pump body, quantitative numerical testing is carried out to completely avoid empirical misjudgment:
·Impeller detection: If the blade wear exceeds 1/3 of the design thickness, the cavitation perforation aperture is greater than 5mm, and the blade is broken, it is directly judged that the impeller is damaged or faulty; If the clearance between the impeller inner hole and the pump shaft is greater than 0.1mm, it is determined that the impeller shaft sleeve is loose.
·Shaft inspection: Use a straightness meter to measure the transmission shaft, and if the bending degree is greater than 0.1mm/m, determine the shaft bending deformation fault; The internal clearance of the guide bearing is greater than 0.2mm for small pumps and greater than 0.3mm for large pumps, indicating bearing wear and failure.
·Overcurrent clearance detection: If the clearance between the impeller and the wear-resistant ring exceeds the original design value by 1.5 times, it is determined that the wear-resistant ring has failed due to wear, which is a hidden fault point that is easily overlooked in routine inspections.
·Connection component inspection: Check the transmission shaft sleeve coupling for loose threads and broken stop pins, and determine the power transmission interruption fault; The flange gasket of the water lifting pipe is damaged, indicating a pipeline leakage fault.
·Immediate shutdown level fault: The current exceeds the set value by more than 20%, the vibration is greater than 4.5mm/s, and there is no water discharge at all. The pump must be stopped immediately to avoid irreversible accidents such as shaft breakage and motor burnout.
·Limited maintenance level faults: vibration of 1.8-4.5mm/s, flow decrease of 10% -20%, slight leakage, can be scheduled for shutdown and maintenance within 1-2 operating cycles, without the need for emergency pump shutdown.
·Normal warning level fault: The parameters fluctuate slightly, and all quantitative indicators are within the qualified range. Only daily inspections need to be strengthened, and there is no need to arrange maintenance for the vertical semi submersible long shaft deep well turbine pump.