Submersible axial flow pumps often encounter issues such as oil leakage, electrical leakage, tripping, insufficient head, impeller failure, low flow rate, and low speed. Below, we provide a detailed analysis of these common problems and queries:

1. Low impeller speed, unable to achieve the required head.

Many customers have found that the newly purchased submersible pumps do not reach the specified head height during initial operation, and measurements reveal a lower speed as well. This situation may be due to incorrect wiring, and it is recommended to swap the hot line. Additionally, it's possible that the submersible pump is of low quality, resulting in the pump not achieving the required head height.

2. Submersible pump has low water output and insufficient flow rate.

Removed the submersible pump and inspected the roller for smooth operation; the motor rotates upon power supply. Upon disassembly of the pump, it was discovered that the shaft at the lower end of the submersible pump was loose between the bearing, and the rotor had shifted downward, resulting in weak roller rotation and reduced output power. Appropriate washers were placed between the rotor and bearing to elevate the rotor, and upon testing, the issue was resolved.

3. Upon power-on, the impeller does not rotate.

Upon powering on, the submersible pump emits a humming noise but the impeller does not rotate. After shutting off the power, attempt to manually rotate the impeller at the inlet. If it's difficult to move, it indicates that the rotor is stuck. Disassemble the pump to inspect if the bottom bearing ball of the rotor has broken, causing the rotor to jam. If the impeller can be rotated, but it still doesn't spin when powered on, the issue may be severe wear on the bearings. When powered, the stator's magnetic field attracts the rotor, preventing it from rotating. Replace the bearings, reassemble the pump, and the impeller rotates smoothly, resolving the issue.

Common Issues and Analysis of Submersible Pumps

4. Oil leakage

The leakage of submersible pumps is primarily due to severe wear of the seal box, which results in oil leakage from the oil chamber of the seal box or poor sealing at the wire junction box.

When the oil chamber of a sealed box leaks oil, oil stains can be seen at the water intake joint. There is an oil filling hole at the water intake joint. Unscrew the screw and investigate whether the oil chamber has water intake. If the oil chamber has water intake, it indicates poor sealing, and the sealed box should be replaced, as severe water intake may seep into the motor. If there is an oil-fouling phenomenon at the root of the submersible pump cable, it is a case of oil leakage inside the motor. This is usually caused by poor sealing of the sealing gasket or using substandard leads after the motor is re-wound; some cases are caused by the pump connector plate breaking. After inspection, replace with qualified new products.

5. Electrical leakage

Leakage is a common issue in submersible axial flow pumps and one of the risk factors for personal harm. The problem occurs when the circuit breaker in the transformer power room trips upon closing the switch (it would be quite dangerous without a leakage protector, potentially causing motor burnout). This is primarily due to water entering the submersible pump's body, reducing the insulation resistance of the motor windings, thereby triggering the protector. At this point, use a multimeter's R×10kΩ range to measure the leakage resistance between the motor windings and the casing. Over time, the mechanical seal face of the submersible pump wears severely, allowing water to seep in and wet the motor windings, causing leakage. The removed submersible pump motor can be dried in an oven or using a 100-200W incandescent bulb; once the insulation resistance is high, replace the mechanical seal, reassemble the pump, and it can be put back into use.