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Today, we will examine the factors that cause water pump burnout, and then focus on the maintenance of pressure tanks. 1. First, determine whether the motor has burned out due to a mechanical fault or because of a problem with its coils (an electrical fault). Electrical faults include short circuits, open circuits in the stator and rotor windings, as well as issues with the starting equipment ； Mechanical failures include excessive vibration, overheating of bearings, friction between the stator and rotor, and abnormal noises. If the fault is related to burned-out coils, it is mainly caused by overcurrent; sometimes too high or too low voltage can also lead to heating and short circuits in the coils. Therefore, first check whether the voltage during operation differs significantly from the rated voltage. The coil of the pump motor has burned out; there was an overcurrent short circuit in the pump’s electrical system. The possible causes are as follows: 1) The equipment was operating under overload conditions, causing the motor to run at its rated current or above for an extended period of time. It is particularly important to note that the starting current of a motor is 3-5 times its rated current; therefore, it should be avoided as much as possible to start the equipment under load or at full load (this depends mainly on the margin between the motor’s rated current and its normal operating current). 2) The motor operates in a relatively humid working environment. Before starting the motor, it is necessary to check the insulation of the coils with respect to ground as well as between phases. The insulation requirements vary depending on the voltage level at which the motor is used; relevant **standards can be referred to for such checks. During the operation of the motor, attention should be paid to its waterproofing and moisture resistance. 3) Mechanical failures of the pump cause the motor to be overloaded, resulting in excessive current that burns out the windings. 4) There is a problem with the motor’s heat dissipation. Typical motor coils use air-cooled housings, while submersible pumps use water-cooled housings. Large motors are often cooled using air-to-air heat exchangers or air-to-water heat exchangers. If the cooling water (air) is interrupted, preventing the coil from dissipating heat, it may burn out. Figure 2 shows the scenario of a mechanical seal being damaged. The actual operating head is either too low or too high compared to the head specified on the pump’s nameplate. The head of a centrifugal pump is used to overcome elevation differences and resistances; when a pump operates at a high head, its flow rate corresponds to that at the design point. However, when it operates at a lower head, the resistance at the pump’s outlet decreases, which results in an increase in the pump’s flow rate. This leads to overloading of the motor, and if the overload persists to a certain extent, the motor can be damaged. For example, if a feed pump has a head of 50 meters and a flow rate of 50 cubic meters per hour, its flow rate remains at 50 cubic meters per hour when supplying water to a height of 50 meters. However, when supplying water to a height of 40 meters, the reduced height and resistance cause the flow rate to increase to 80–90 cubic meters per hour or even more; in such cases, the motor may overheat or get damaged. If he pours water from a height of 60 meters. As his height and resistance increase, the flow rate can drop to just over 30 cubic meters per hour; when the motor operates at full load for a long time without any rest, it will overheat and this can lead to engine damage. The mechanical seal has burned out. 3. The water pump operates for too long without water; in the case of a water-cooled submersible motor, without water, there is no way for water to cool the motor, which leads to an increase in its temperature. If the motor does not have an overheat protection device, it can burn out within a few seconds to 1 minute. Therefore, insufficient water is the main reason for rapid motor damage! 4. Starting under load can cause damage to the motor. When a three-phase motor starts, the starting current is very high, reaching 4 to 7 times the rated current. Such a high starting current can cause a significant voltage drop in the circuit in a short period of time, which not only affects the motor’s own starting process but also interferes with the proper operation of other motors and electrical devices on the same circuit. 5. Phase loss is another major cause of motor damage. For both ordinary motors and submersible motors, phase loss accounts for 6 to 8 percent of cases of motor damage; bearing failure is responsible for 2 percent of such cases. 6. Refurbishing defective pumps: Consumers’ insistence on lower prices is a factor, but unscrupulous manufacturers playing the role of refiners is another major cause. Such manufacturers refurbish defective pumps through recycling and after-sales services to keep prices low. In the current highly competitive market for hardware and mechanical equipment, lower prices mean an advantage in this market, which in turn leads to a vicious cycle; ultimately, it is the entire industry and consumers who suffer as a result. The pump coil has burned out. Do pumps equipped with air tanks last longer, or are they more prone to motor burnout? The working principle of the air pressure tank will not be explained in detail here; only four parameters will be mentioned: the starting pressure P1 of the water pump, the stopping pressure P2 of the water pump, the pre-charge pressure P3 of the air pressure tank, and the maximum pressure P4 of the air pressure tank. Simply put, when P3 is less than P1, the water pump starts up and begins to pump water. When P4 is approximately P2, the water pump stops working. Therefore, if the distance between P1 and P2 of the water pump is too small, the pump will tend to operate frequently, and frequent operation can easily cause the motor to burn out. Additionally, the pre-charge pressure P3 of the air tank is not 0; it is usually around 1 to 4 kilograms. All these parameters need to be adjusted according to the actual conditions. Don’t buy a water pump and an air tank without checking or making any adjustments, and then connect the pipes directly – otherwise, the motor may get damaged and you won’t know why! As we all know, the main reason for motor damage is the frequent starting and stopping of the water pump. So the question arises: why does the water pump start and stop frequently? 1. This occurs because, when the user installs the self-priming pump, check valves are not installed at the inlet and outlet, which allows water to flow back rapidly after the pump stops. As a result, the outlet pressure drops below the set value, prompting the fully automatic variable-frequency water pump to start again. The solution to the frequent startups of this fully automatic variable-frequency water pump is to install a check valve at the outlet of the self-priming pump, which will resolve the issue. 2. If the faucet is not closed properly, or if water is leaking from somewhere else and this leads to a drop in outlet pressure, the self-priming pump will also start automatically. Checking whether the faucets are closed properly and identifying where the leaks are is the solution to the problem of frequent startups of the fully automatic variable-frequency water pump. If the leakage is not severe, using an HM-type household self-priming pump for tap water will prevent frequent starts and stops. 3. The issue is caused by the large pressure required due to the long transmission distance and high height, and the pressure set on the pressure controller is not sufficient for the intended use. To resolve this, one can first open the controller cover and then use an flat-head screwdriver to turn the adjustment knob in the middle clockwise upward in order to achieve a higher shutdown pressure. 4. Another possible reason for the frequent starting of fully automatic variable-frequency water pumps is the lack of gas in the pressure tank attached to the self-priming pump. Check whether there is any leakage in the diaphragm or bladder of the pressure tank; if there is leakage, inflate it with pressure or replace the pressure tank.