After a period of use, any mechanical equipment will encounter various issues. This article discusses some common pump problems and their corresponding solutions.

1. Unable to launch

Firstly, inspect the power supply: ensure the connections are secure; verify that the switches are tightly engaged; check for blown fuses; and confirm that the three-phase power is balanced. In case of any circuit breaks, poor contact, fuse blowouts, or unbalanced phases, identify the cause and promptly carry out repairs.

Next, inspect for mechanical failures within the pump itself, common causes include: too tight packing or debris trapped between the impeller and pump housing causing blockage; rust on the pump shaft, bearings, and leakage rings; severely bent pump shaft. Solutions: loosen the packing, clear the water channel; disassemble the pump housing to remove debris and rust; remove and straighten or replace the pump shaft.

2. Pump overheating

Reason: Bearing damage; insufficient gap in the rolling bearing or bracket cover; pump shaft bent or two shafts not concentric; too tight belt; insufficient or poor oil quality; clogged balancing holes on the impeller, causing it to lose balance and increase thrust to one side.

Exclusion Methods: Replace the bearing; remove the rear cover and add shims between the bracket and bearing housing; inspect the pump shaft or adjust the concentricity of the two shafts; loosen the belt tension appropriately; add clean grease, filling approximately 60% of the bearing cavity; and clear the堵塞物 from the balancing hole.

3. Low Traffic

This is due to: mismatched power speed or belt slippage causing low rotation speed; too small installation angle of the axial flow pump blades; insufficient head; excessively long pipeline or pipeline with sharp bends; high suction head; local blockage in the bottom valve, pipeline, and impeller, or missing impeller parts; and severe leakage in the outlet pipe.

Exclusion Methods: Restore rated speed, clean belt grease, adjust belt tension; adjust blade angle, lower pump installation position, shorten pipeline or alter pipeline curvature; seal pump air leaks, tighten packing; remove blockages, replace impeller; replace leakage rings, plug water leaks.

4. Inadequate water intake

The cause is air in the pump casing or air accumulation in the intake pipe, or the bottom valve not closing tightly resulting in insufficient water inflow, severe air leakage from the vacuum pump stuffing, or the gate valve or flap door not closing properly.

Exclusion Method: First, bring up the water pressure, then fill the pump housing with water, and then start the machine. Meanwhile, check if the check valve is tight and if there are any air leakage in the pipeline and joints. If air leakage is found, disassemble and apply lubricating oil or paint at the joint, then tighten the screws. Inspect the oil seal ring of the pump shaft; if it is severely worn, replace with new parts. Pipeline leakage or air leakage may be due to loosely tightened nuts during installation. If the leakage is not severe, apply cement to the leaking or air-leaking areas, or use asphalt oil mixed cement paste. Temporary repairs can be made with some wet mud or soft soap. If there is leakage at the joints, use a wrench to tighten the nut; if the leakage is severe, it is necessary to disassemble and reassemble, replace cracked pipes; reduce the lift height, and submerge the pump outlet 0.5 meters underwater.

5. Severe Vibration

Several main reasons include: unbalanced electric rotor; poor coupling fit; worn and bent bearings; loose or cracked parts in the rotating section; and unstable pipeline supports.

Adjustments, repairs, reinforcement, straightening, and replacements are among the methods that can be employed. The aforementioned issues are common causes of pump failure, but not the only causes. In practice, when addressing failures, it is essential to follow a principle of tackling external issues first before moving inward, and avoid acting blindly.

6. Auxiliary power motor overheating

Four reasons:

Firstly, due to power supply issues: voltage fluctuations that are either too high or too low can cause motor overheating under specific loads if the voltage variation exceeds +10% to -5% of the rated value; unbalanced three-phase voltage can lead to excessive overheating of the winding if the imbalance exceeds 5%; and single-phase operation, experience shows that over 85% of agricultural motors are destroyed due to single-phase operation, so protective devices against single-phase operation should be installed on the motor.

Secondly, the issue with pumps: mismatched power selection, a small horse pulling a heavy cart, leading to long-term overload operation of the motor, causing excessive motor temperature; frequent startups, and motors designed for short-term or intermittent operation being used continuously. The number of startups should be limited, and heat protection should be selected correctly, using the motor as indicated by the manufacturer's specifications.

The third cause is inherent to the electric motor itself: incorrect wiring, mistakenly connecting it in delta instead of Y, leading to a rapid rise in motor temperature; stator winding issues such as phase-to-phase short circuits, turn-to-turn short circuits, or partial grounding, which may cause localized overheating of the motor in mild cases, and insulation burnout in severe cases; squirrel cage rotor broken bars or defects, causing the core temperature to rise quickly within 1 to 2 hours of operation; ventilation system failure, check if the fan is damaged, the rotation direction is correct, and if the ventilation ducts are blocked; bearing wear and rotor eccentricity causing rubbing between the stator and rotor cores, emitting metal clanging sounds, with the core temperature rising quickly, and in severe cases, the motor may smoke or even have its coils burned out.

四是 work environment-related reasons: The motor winding becomes damp or dust, oil, and dirt accumulate on the winding, leading to reduced insulation. The insulation resistance of the motor should be measured, and the winding should be cleaned and dried; the ambient temperature is too high. When the ambient temperature exceeds 35°C, the high intake air temperature can cause the motor temperature to rise excessively, so efforts should be made to improve its working environment, such as setting up sheds to shade. Note: In case of electrical failures, it is essential to have the repair done by an electrician with a professional certification. Individuals with limited knowledge should not attempt repairs blindly to prevent accidents resulting in personal injury.

7. Submersible pumps and deep well pumps are not drawing water or are producing insufficient water supply.

First, examine the current the pump is running at right now and compare it to the normal operating current. If it's smaller than the normal current (basically two-thirds of the normal current), issues like blade wear and a clogged check valve on the pump head may be present. If it's the same as the normal current, problems like leaking pipe gaskets, leaking pipes, or a leaking pump body might be the cause. If the current is higher than the normal operating current, it's likely due to worn-out wearing parts. Additionally, if the cable is damaged, the water volume will remain the same as usual, but the current will increase. The current for a 3-phase 380V motor is typically 2.2A. These causes can be identified by repair personnel who regularly service deep well pumps.