How to diagnose specific faults of a vertical multistage submerged long-shaft deep-well turbine pump?

The specific faults of a vertical multi-stage submerged long-shaft deep-well turbine pump can be determined through two levels: quick diagnosis without disassembly on the well and precise detection through disassembly. This approach enables precise localization of the specific faults of the vertical submerged multi-stage long-shaft deep-well turbine pump, eliminating the need for blind disassembly of the turbine pump.
· Fault corresponding to abnormal current: If the motor current continuously exceeds the rated value, it is firstly determined to be due to impeller overload and over-flow operation, large shaft alignment deviation, wear of the guide bearing, or the density/viscosity of the conveying medium far exceeding the design value.
· Faults corresponding to abnormal water discharge: A sudden decrease in water flow, significant pressure fluctuations, or even no water discharge at all directly correspond to blockages in the suction inlet filter, leakage in the water lifting pipe, broken drive shaft, or loosened and worn impeller.
· Faults corresponding to vibration and abnormal noise: If the well platform can perceive obvious shaking and the operation emits a "squeaking" friction sound or a "grunting" vortex vibration noise, it is determined to be due to excessive shaft bending, bearing wear, uneven liquid intake at the suction port, or imbalance of the impeller.
· Faults corresponding to abnormal sealing: If there are more than 5 drops of leakage per minute or even a large amount of water spraying at the shaft seal, it is determined to be due to wear of the packing/mechanical seal or improper tightness of the gland; if the temperature at the packing box is abnormally high, it is determined to be due to a bent drive shaft or insufficient water leakage from the packing box.
· Faults corresponding to abnormal motor operation: If the motor does not rotate when powered on and produces abnormal noise, it is determined to be a power phase loss, stator single-phase short circuit, or rubber bearing expansion; if the motor speed is significantly lower after startup, it is determined to be a phase winding head and tail connection error or too low supply voltage.
1. Check the water filter screen at the suction inlet. If it is completely blocked by sediment or foreign objects, it is directly determined as a water filter screen blockage fault.
2. Inspect the straightness of the transmission shaft. If the bending exceeds 0.1mm per meter, it is determined as a shaft bending deformation fault.
3. Measure the internal clearance of the guide bearing. If the clearance is greater than 0.2mm for small pumps or greater than 0.3mm for large pumps, it is determined as a bearing wear failure.
4. Inspect the impeller blades. If the wear exceeds 1/3 of the original thickness, or if there are cavitation holes or fractures, it is determined as a damaged impeller fault.
5. Measure the fit clearance between the impeller and the wear-resistant ring. If it exceeds 1.5 times the original design value, it is determined as a wear-resistant ring wear failure.
6. Check the motor bearing area. If the temperature exceeds the ambient temperature by more than 35℃, it is determined to be a fault due to bearing damage, excessive/insufficient lubricating grease, or unclean grease.
· In the event of any of the following phenomena: severe current exceeding, violent vibration and abnormal noise, or complete failure to dispense water, it shall be immediately determined as a high-risk fault. The machine must be shut down immediately to prevent irreversible serious damage such as motor burnout or shaft breakage.
· If only minor leakage or a small decrease in flow occurs, it is classified as a warning-level fault. Maintenance downtime can be arranged within 1-2 operating cycles, and there is no need for an emergency pump shutdown.