Precautions for Submersible Pump Maintenance

1. Replace lubricating oil: Open the oil fill/drain screws for both the seal chamber and the motor housing. Drain all existing lubricant and replace it with fresh oil to ensure the lubrication system functions correctly.

2. Inspect wear parts: Components such as the impeller, retaining rings, shaft sleeves, and bearing housings are subject to wear. First, disassemble the pump section to check the condition of these parts. The use of damaged or substandard components is strictly prohibited.

3. Prevent rust-related seizure: Before using the pump in the spring, remove the uppermost pump casing and manually rotate the impeller before switching on the power. This prevents the motor from burning out due to failure to start caused by rust-induced seizing of components. This maintenance step is particularly critical for water-filled motors.

4. Dry the motor: Use a 500V megohmmeter to measure the insulation resistance between the submersible pump's windings and the casing. If the resistance is below 0.5 MΩ, moisture must be removed from the motor. Drying methods include external drying, current-based drying, and a combined method using both. External drying involves using an external heat source; common measures include: (1) Hot air blowing: Using a blower with a heating element (or a standard hair dryer for small agricultural pumps) to blow hot air; (2) Light bulb baking: Baking the motor inside an enclosed box using several 200-watt light bulbs (ensure the temperature remains below 125°C); (3) Current-based drying: Connect the motor's three-phase windings in series or parallel (depending on impedance and power supply capacity), connect a variable resistor, adjust the current to approximately 60% of the rated value, and energize the motor to dry it.

5. Ensure sealing integrity: Agricultural submersible pumps have strict sealing requirements. When replacing the lubricant in the seal chamber, if the oil appears cloudy or has a high water content, the entire assembly, seal housing, or sealing ring must be replaced to guarantee effective sealing performance.

 

6. Inspect the bearings: Check the upper and lower bearings of the motor section. If wear or excessive clearance is detected, replace the bearings immediately; operating the motor in a defective state is strictly prohibited. Inspection methods are as follows: If a "clicking" sound occurs during operation-with a frequency proportional to the rotational speed-and the rotor feels stiff when turned by hand, this indicates roughness or surface pitting (spalling) on ​​the bearing raceways. If an intermittent "grinding" or "choking" sound is heard and the rotor encounters irregular resistance or "dead spots" when turned by hand, this generally indicates a damaged ball cage, a cracked inner race, or broken balls. In any of these cases, the bearings must be replaced to prevent further damage.

7. Ensure bearing lubrication: For water-filled submersible pumps, inspect and replace the oil seals and lithium-based grease in the bearing housings of the upper and lower end covers to ensure the bearings remain well-lubricated during long-term operation.