How to Maintain Submersible Pump

May 16, 2023

Various problems will inevitably occur in the daily operation of the submersible pump. In order to extend its service life and ensure the normal operation of the submersible pump and its associated system, the submersible pump and its control system should be fully maintained at least once a year. Today we come to understand some of the main factors affecting the operation of submersible pump, submersible pump daily maintenance points and common faults and troubleshooting methods.


1, the main factors affecting the operation of submersible pump

In general, the main factors affecting the normal operation of submersible pump are as follows:



1). Electric leakage problem. Submersible pump, as the name suggests, is a machine pump into the water work, so the leakage problem is one of the important factors affecting the normal operation of submersible pump.

2). Blocked rotation. When the submersible pump is blocked, the stator windings will generate 5 ~ 7 times the normal full load current. If there is no corresponding protection measures, the submersible pump will burn out soon. There are many reasons for the submersible pump to block, such as impeller stuck, mechanical seal debris stuck shaft, dirt winding and so on.

3). The power supply voltage or frequency is too low.

4). Wear and rust. Wear will greatly reduce the performance of the electric pump, flow, head and efficiency are reduced, impeller and pump cover rust will cause blocking. Corrosion of submersible pump parts will not only affect the performance of the pump, but also shorten the service life.

5). The cable is broken or broken. Cable breakage, break is not only easy to cause electric shock accident, and the pump running is likely to be in a two-phase working state, neither water and easy to damage the motor.


2. Prepare for the use of submersible pump


1). Check whether the cable is broken or broken. Before use, it is necessary to observe the appearance of the cable, and to use a multimeter or megohm meter to check whether the cable path. There should be no oil leakage at the cable outlet. 

2). Before the new pump is used or the standby pump that has been placed for a long time is started, the insulation of the stator to the shell shall be measured by megohm meter at least 1 megohm; otherwise, the motor windings shall be dried to improve the insulation level.

3). Check whether the submersible pump is leaking oil. The possible way of oil leakage of submersible pump is the cable connection, the seal at the sealing room of the oil screw and the seal of the O-shaped seal ring. Check to see if there is an oil leak. The cause of oil leakage at the oil screw is that the screw is not tightened, or the oil resistant rubber liner under the screw is damaged. If the leakage is determined at the O-ring seal, it is mostly because the O-ring seal fails. At this time, the electric pump needs to be dismantled to replace the seal ring.

4). Before the submersible pump that has been out of use for a long time is used again, it should be started after disk impeller, to prevent the parts from rusting and starting without water and burning the motor winding.


3. Matters needing attention in operation of submersible pump


1). When the submersible sewage pump is running without water, the running time is strictly prohibited to exceed the rated time. The volume of the suction pool can ensure the high water level when the submersible pump is opened and in operation, so as to ensure the cooling effect of the motor and avoid frequent startup and shutdown caused by too large water level fluctuation. The frequent startup of large and medium-sized submersible pump has a great impact on the performance of the pump.

2). When the humidity sensor or temperature sensor sends an alarm, or when the vibration and noise of the pump body are abnormal during operation; When the output water pressure drops and the power consumption increases significantly, the submersible sewage pump shall be shut down immediately for maintenance.

3). Some submersible pumps with poor sealing are immersed in water for a long time. Even if they are not used, the insulation value will gradually decline and eventually cannot be put into use. Therefore, the submersible pump in the suction pool reserve sometimes can not play the role of reserve, if conditions permit, can be in the pool dry reserve, such as the operation of a submersible pump failure, immediately shut down after lifting up, the standby pump put down.

4). The submersible pump can not be opened or stopped too frequently, otherwise it will affect the service life of the submersible pump. When the submersible pump stops, the water in the pipeline produces reflux, and the immediate restart will cause the overload of the electric pump when it starts, and bear unnecessary impact load; In addition, the submersible pump too frequently open, stop will damage the impact capacity of the poor parts, and bring damage to the whole pump. 

5). After shutdown, the motor cannot be restarted before it completely stops running.

6). The power supply must be cut off when checking the electric pump.

7). When the submersible pump is working, do not wash items, swim or put livestock into the water nearby, so as to avoid electric shock when the electric pump leaks.




4, submersible pump maintenance and maintenance


1). Add gas regularly and change oil regularly. Submersible pump every 1000 hours, must be replaced once sealed oil, once a year to replace the motor internal oil. For the water-filled submersible pump, the upper and lower end covers, the skeleton oil seals and lithium lubricating oil in the bearing room should be replaced regularly to ensure good lubrication. For the small submersible pump with mechanical seal, must often open the sealing chamber to fill the screw hole with lubricating oil, so that the mechanical seal in a good lubrication state, so that its working life is fully guaranteed.

2). Replace the sealing box promptly. If more water is found to leak into the pump (normal leakage is 0.1mL/h), the sealing box should be replaced in time, and the insulation resistance value of the motor winding should be measured at the same time. If the insulation resistance value is less than 0.5 megohm, it needs to be dried, and the method is the same as that of the general motor winding drying. When replacing the sealing box, attention should be paid to the integrity of the outer diameter and the O-shaped sealing ring in the shaft hole, otherwise the water will leak into the inside of the submersible pump and damage the motor winding.

3). Measure the insulation resistance frequently. Use 500V or 1000V megohm meter to measure the insulation resistance value of the stator winding of the electric pump to the casing. It can only be used if the value is more than 1 megohm (the minimum is not less than 0.5 megohm). Otherwise, the winding should be repaired or dried to ensure the safety of use.

4). Keep it properly. When not used for a long time, the submersible sewage pump should not be soaked in water for a long time, and should be kept in a dry and ventilated room. The rubber cable of submersible pump should avoid the sunlight when it is kept, otherwise it is easy to age, and the surface will have cracks. In serious cases, it will cause the reduction of insulation resistance or make water enter the outlet box of the submersible pump through the cable sheath, resulting in serious consequences such as the interphase short circuit of the power line or the winding insulation resistance to the ground is zero.

5). Timely anti-rust treatment of submersible pump surface. The submersible pump should be painted timely according to the corrosion of the surface of the submersible pump after one year. Its internal paint anti - rust should depend on the pump type and corrosion conditions. In general, when the interior is full of oil, it will not rust. At this time, the interior does not need to be painted.

6). Submersible pump shall be maintained once a year (or 2500 hours of cumulative operation), including: disassemble the motor of pump, clean all parts, remove scale and rust, check its integrity, timely repair or replacement of damaged parts; Replace the lubricating oil inside the sealing room and the motor; If the lubricating oil released in the sealing room is turbid and the water content exceeds 50mL, it is necessary to replace the integral sealing box or dynamic or static sealing ring.

7). Air pressure test. After the maintenance of the electric pump or the replacement of the mechanical seal, the air pressure test should be 0.2MPa to check whether the O-ring at the mating surface of the parts and the two covers of the mechanical seal have gas leakage phenomenon. If there is gas leakage phenomenon, the leakage parts must be reassembled or replaced.

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