In sewage treatment plant, water pump is the most commonly used moving equipment, and also the movable equipment which is prone to problems. The treatment of pump failure should be based on specific problems and actual analysis, and the principle of "outside first and then inside" should be followed, and the operation should not be blind.

First, the power supply should be checked: whether the connection of the connector is reliable; Whether the switch contacts carefully; Whether the fuse is blown; Whether the three-phase power supply is lack of equal. If there is open circuit, poor contact, fuse fuse and phase shortage, find out the reason and repair it in time. Second, check whether it is a mechanical failure of the pump itself.

Condition I. water pump can not be started

Common causes: packing is too tight or the impeller and pump body are piled up and blocked by debris; The pump shaft, bearing and leakage reduction ring are rusted; The pump shaft is seriously bent, etc.

The method of elimination: loosen the packing and dredge the water channel; Remove the sundries and rust from the pump body; Remove the pump shaft alignment or replace the new pump shaft.

Disease II. Insufficient flow

Causes: most of them are water pipe leakage and bottom valve leakage; The water inlet is blocked; The depth of water entering of bottom valve is insufficient; The pump speed is too low; The sealing ring or impeller is worn too much; The water absorption height is over standard.

Elimination method: check the suction pipe and bottom valve to block the leakage air source; Clean up the silt or blockage at the water inlet; The depth of water entering of bottom valve must be 1.5 times larger than the diameter of inlet pipe, and the depth of bottom valve water inlet shall be increased; Check the power supply voltage, improve the speed of the water pump, and replace the sealing ring or impeller; Lower the installation position of the water pump or replace the high lift pump.

Disease 3. No water

Causes: there is air or gas accumulation in the water inlet pipe in the pump, or the bottom valve is not closed tightly, the water filling of the vacuum pump is not enough to leak, and the gate valve or clapper valve is not closed tightly.

Exclusion:

1. first put the water pressure up, then fill the pump body with water, and then start the machine. Meanwhile, check whether the check valve is tight, whether the pipeline and joint have air leakage. If any air leakage is found, apply lubricating oil or paint on the joint after removal, and tighten the screw.

2. check the oil seal ring of the water pump shaft, and replace the new parts if the wear is serious.

3. the pipeline is leaking or leaking. The nut may not be tightened when it is installed. If the leakage is not serious, cement can be applied to the place where the air leakage or leakage is leakage, or the cement slurry mixed with asphalt oil can be applied. Temporary repairs can be done with wet mud or soft soap. If there is water leakage at the joint, screw the nut with a wrench. If the leakage is serious, it must be disassembled again and the cracked pipe should be replaced; Reduce the lift and press the pipe mouth of the water pump into the water for 0.5m.

Disease 4. Water pump does not come out

Causes: pump body and water absorption pipe are not filled with water; The dynamic water level is lower than the water pump filter pipe; Water suction pipe rupture, etc.

Troubleshooting: eliminate the bottom valve fault and fill up the water diversion; Lower the installation position of the water pump, make the filter pipe under the dynamic water level, or raise the filter pipe at the same dynamic water level to pump water; Repair or replace the suction pipe.

Condition v. pump body vibrates or produces noise

Causes: the pump is not installed firmly or the pump is too high; The ball bearing of motor is damaged; The main shaft of water pump is bent or is not concentric or parallel with the motor spindle.

Treatment method: stabilize the water pump or reduce the installation height of the pump; Replace the ball bearing of motor; Correct the bent water pump spindle or adjust the relative position of the pump and motor.

Condition 6. Excessive power consumption

Cause: the water pump speed is too high; The main shaft of the water pump is bent or the main shaft of the pump is not concentric or parallel with the motor spindle; The pump head is not suitable; The pump inhales sediment or blockage; Motor ball bearing damaged, etc.

Treatment method: check the circuit voltage and reduce the speed of water pump; Correct the main shaft of the water pump or adjust the relative position of the pump and the motor; Select the pump with proper lift; Clean up sediment or blockage; Replace the ball bearing of the motor.

Condition 7. Drive shaft or motor bearing overheated

Causes: lack of lubricating oil or bearing rupture, etc.

Treatment: fill in lubricating oil or replace bearing.

These are the common causes of "disease" of water pump, not all reasons. In practice, the fault should be handled. According to the specific problems and actual analysis, the principle of "outside first and then inside" should be followed, and the operation should not be blindly carried out.

Before analyzing the water pump failure, we must learn how to use universal meter and megohmmeter. The precautions for using are as follows:

1. If the measured voltage or current cannot be estimated in advance, it should be measured once in the highest range block, and then gradually reduce the range to the appropriate position as the case may be. After measurement, the range switch shall be set to the highest voltage and the power supply shall be turned off.

2. When measuring voltage, the digital multimeter shall be parallel with the circuit under test; The current measurement should be in series with the circuit under test, and the positive and negative polarity are not necessary for the direct flow measurement.

3. When the AC voltage is measured by mistake or the AC voltage is misused, the display will display "000", or the number at the low level will jump.

4. It is forbidden to change the range when measuring high voltage (over 220V) or high current (above 0.5A), so as to prevent arc and burn down the switch contacts.

5. When "batt" or "low bat" is displayed, it indicates that the battery voltage is lower than the working voltage.

Problem 1: motor overload when water pump is working

Generally, the motor has a rated operating power, which is called rated power, in watt (W) or kW (kw). If in some cases, the actual operating power of the motor exceeds the matching rated power of the pump, this situation is called motor overload. Motor overload has the following forms:

1. The motor has too much heat;

2. The motor speed drops, even reaches zero, which shows that the motor does not rotate;

3. The motor has a low hum and a large vibration;

4. The motor load changes dramatically, and the motor speed will be changed from high to low.

List of causes and Solutions

Problem 2: phase shortage of three-phase motor when the water pump is running

The three-phase motor must be powered by three cables in order to achieve the three-phase balanced operation; If the power supply is provided by two power lines, the longer the operation time will cause the motor to burn down due to phase shortage. The method of judging the motor phase missing:

1. The voltage of three power lines is measured by universal meter, whether there is no voltage drop in one phase;

2. Check whether the copper wires in three power lines are black, and the copper wires of one power cord are not blackened and kept as they are;

3. Open the motor cavity, generally, the two phases of the three-phase motor will burn down, and the other phase will remain the same.

List of causes and Solutions

Problem 3: sudden power trip of water pump motor

If the matched power protector is in line with the pump motor, the protector will not trip under normal conditions. The main reasons for the trip of the protector are as follows:

1. Pump motor overload;

2. The temperature rise of the pump motor is too high;

3. The running current of the pump motor is too high;

4. The power supply voltage of the water pump is too high.

List of causes and Solutions

Problem 4: the water pump motor is in water

In general, water inlet is not allowed for pump motor (except for water immersed pump). The following conditions exist for the motor water inflow:

1. Water inlet due to damage of waterproof cable;

2. The power line of the water pump motor is not sealed well for water inlet;

3. The sealing structure at the inlet of the pump motor is damaged and the water is fed;

4. The mechanical seal of the water pump is damaged and the water is fed;

5. The O-ring of water pump is damaged and the water is fed;

6. The bolt at the sealing part is not tightened, which leads to the water inflow of the motor;

7. The parts of the water pump are damaged and the water seepage is damaged.

List of causes and Solutions

Problem 5: leakage of water pump motor

In general, the pump motor will not leak, but the motor will leak in the following cases:

1. Leakage of waterproof cable damaged;

2. There is no leakage at the connection of power line of water pump motor;

3. Water leakage of water pump motor;

4. Leakage after the motor of water pump is burned;

5. Low insulation resistance leads to leakage.

In order to ensure the safety of the personal property of the pump under the condition of electric leakage, the grounding of the pump must be installed correctly, and the leakage switch should be installed at the same time.

List of causes and Solutions

Problem 6: the pump motor cannot be started

The pump motor will not start (not rotating or low speed) generally due to the following reasons:

1. Leakage of water pump;

2. The voltage of the matched power supply is too low;

3. The impeller of the water pump is stuck due to foreign matters;

4. The bearing is damaged and stuck;

5. Motor overload operation (overload);

6. Three phase water pump three-phase power supply reverse connection;

7. Three phase motor is short of phase;

8. Motor cleaning;

9. Capacitor damaged, connected reverse, too small capacity.

List of causes and Solutions