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Analysis and troubleshooting of seven major faults of submersible pump

Analysis and troubleshooting of seven major faults of submersible pump

2020-07-24

1. Analysis of the reasons why the submersible pump does not discharge liquid or has a small flow rate:

(1) The installation height of the water pump is too high, which makes the impeller immersion depth insufficient, resulting in a decrease in the water output of the water pump; control the allowable deviation of the installation elevation of the water pump and cannot be expanded at will.

(2) The direction of the water pump is reversed; before the test operation of the water pump, the motor is idling, and the direction of rotation is checked to make it consistent with the water pump. If the above situation occurs during use, check whether the power phase sequence has changed.

(3) The outlet valve cannot be opened; check the valve and maintain it frequently.

(4) The outlet pipeline is not unblocked or the impeller is blocked; clean up the blockage of the pipeline and impeller, and often salvage the debris in the reservoir.

(5) The wear ring at the lower end of the pump is severely worn or blocked by debris; clean the debris or replace the wear ring.

(6) The density of the pumped liquid is too high or the viscosity is too high; find the reason for the change of water quality and treat it

(7) The impeller falls off or is damaged; strengthen or replace the impeller.

(8) When multiple water pumps share pipeline output, there is no one-way valve installed or the one-way valve is not tightly sealed; install or replace the one-way valve after checking the cause.


2. The operation of the submersible pump has abnormal vibration and instability, the main reasons are:

(1) The anchor bolts of the water pump base are not tightened or loose; tighten all anchor bolts evenly

(2) There is no independent support for the outlet pipeline, and the vibration of the pipeline affects the water pump; an independent and stable support is provided for the outlet pipeline of the water pump to prevent the outlet pipe flange of the water pump from bearing the weight.

(3) The impeller is unbalanced or damaged or installed loose; repair or replace the impeller

(4) The upper and lower bearings of the water pump are damaged; replace the upper and lower bearings of the water pump.


3. The main reason for the submersible pump causing excessive current, motor overload or overtemperature:

(1) The working voltage is too low or too high; check the power supply voltage and adjust the output voltage.

(2) There are friction between moving and static parts inside the pump or friction between the impeller and the sealing ring; judge the position of the friction part and eliminate the fault.

(3) The low head and large flow cause the power of the motor to be inconsistent with the characteristics of the water pump; adjust the valve to reduce the flow so that the power of the motor matches the pump.

(4) The pumping density is higher or the viscosity is higher; check the reasons for the change of water quality and change the working conditions of the pump

(5) The bearing is damaged; replace the bearing at both ends of the motor


4.The main reasons and treatment methods for the low insulation resistance of submersible pumps:

(1) When the power cord is installed, the end is immersed in water or the power cord or signal line is damaged, causing water to enter; replace the cable or signal line, and dry the motor.

(2) The mechanical seal is worn or not installed in place; replace the upper and lower mechanical seals and dry the motor.

(3) O-rings are aging and lose their function; replace all sealing rings and dry the motor


5. In the pipeline of the submersible pump, there are often obvious reasons for water leakage at the pipe or flange connection and the treatment method:

(1)The pipeline itself is defective and has not undergone pressure test; 

(2) The gasket joint at the flange connection is not properly treated; 

(3)The flange bolts are not tightened in a reasonable way; the defective pipe should be repaired or even replaced, and the center of the butt pipe should be deviated The oversized ones should be removed and rearranged. After alignment, the connecting bolts should be inserted and tightened in a basically free state. After all the pipelines are installed, the pressure strength and leakage test of the system should be carried out. It must be replaced with a new one.


6. Leakage inside the submersible pump: When the submersible pump leaks, it will cause insulation damage, water immersion in the bearing, and an alarm system that forces the unit to stop running. The main reason: damage to the dynamic seal (mechanical seal) or static seal (special seal for cable inlet, O-ring seal) of the submersible pump causes water seepage, and damage to the power cable or signal cable causes water seepage. Various alarm signals such as water immersion, leakage, humidity, etc. alarm and shutdown; before installation, check the quality of each sealing component; ensure that the end faces of each sealing component are in good contact during installation; check the phase-to-phase and ground insulation resistance of the motor and each alarm before operation Whether the sensing components of the system are intact. When the above failure occurs during operation, replace all damaged seals and cables and dry the motor. The disassembled seals and cables must not be used again.


7.The submersible pump reverses when it stops: 

(1)The pump will reverse when the pump motor is powered off. The main reason is that the check valve in the water outlet pipe or the flapper failed. 

(2)Exclusion measures should be checked before installation, the installation direction of the check valve should be correct, the center of the shutter should be aligned, and the opening and closing should be flexible. Check the check valve or flap door frequently during operation, repair the damaged part or replace the check valve or flap door with guaranteed quality.

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