The drain pump heats but does not pump. When the engine is running, water is not supplied or it flows weakly and unevenly. The difference between submersible and surface models

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A drainage pump for the owners of household plots is in demand and indispensable equipment when it comes time to melt snow or a period of heavy rains. The fact is that excess water can inflict irreparable damage on buildings, flooding basements and eroding the foundation of buildings. During operation, sometimes it is necessary to repair the drainage pump. On the photo you can see what this device looks like.

The drain pump allows to pump the liquid from the pool, pit, tank, well, tank. Is it possible to eliminate the malfunction of it with their own hands, often consumers are interested in this product.

  Types of drainage pumps

   Such units for pumping out dirty water   and drains are superficial and submerged according to their purpose (read: "").

Pumps drainage surface. They are used for pumping liquids from small containers in volume. The apparatus is placed on the ground near the edge of the drain tank (read also: ""). To drain the dirty water, the hose is lowered to the bottom of the container. If the pump functions in automatic mode, the float mechanism must be brought to the switching lever, which will allow monitoring the level of liquid in the pit or reservoir. When the drains rise above a certain level, a float floats up with them and the unit turns on (in more detail: "").

The drain pump has two pipes:

• input - for the collection of dirty water from the waste tank;
• output - necessary for draining the liquid out of the container.

   During operation, make sure that no water gets into it (read: ""). Otherwise, the unit may fail and then it will be necessary to repair the drainage pump with your own hands or with the help of a specialist. Pumping out of drains must be performed faster than their level rises in the well. To the sewer system, the pumps are connected by means of nipples. To do this, measure the diameter of the sewage pipe to within one millimeter.

The advantage of surface pumps is mobility - they can be easily and quickly moved to another location.

Drainage Submersible Pumps. This type of apparatus is used, if necessary, to clean deep reservoirs, and in the case of large-scale floods, for evacuation of surplus water. The unit is lowered into a well or a container, where it is required to pump out the liquid (more: ""). Suction is made through holes in the bottom of the device, and not through the inlet hoses. To prevent large impulses from entering the impeller, there are screen filters in the pump.

   The use of float switches allows a large number of drains to automatically turn on the device. Avoid the possibility of closure when you immerse the device in a liquid can be due to the presence of high-quality electrical insulation.

   If it is necessary to pump out or pump liquid with large fractions, experts recommend using fecal (sewer) pumps having special cutting and cutting elements. They are able to pump and process effluents containing large amounts of waste. The most optimal solution will be the purchase of an automatic sewerage system, which will allow to operate bathrooms that do not have connection to centralized sewage systems.

  The device of the drainage pump

Elements of drainage pumping equipment   are:

• engine - when the device is small, it is in the inner plastic case;
• condenser motor with thermal overload protection switch (in more expensive upgraded models);
• the body is internal and external - in modern, expensive units they are made of high-strength polypropylene reinforced with fiberglass. Also the cases are made of plastic or stainless steel. When the machine is operating, the space between the housings is filled with water, so that the unit does not overheat;
• working shaft is made of stainless steel;
• impeller or impeller are located in the outer casing on the shaft. The configuration of this part depends on the size of the particles of inclusions that the pump can process;
• float switch - serves to turn the machine off and on in automatic mode. This device controls the level of liquid in the well or the tank, providing protection of the mechanism from "dry running". It is responsible for the timely activation of the device.

   The equipment will serve long term, and the repair of the drain pump by oneself will not be necessary provided that the presence of fibrous inclusions is minimal in the liquid, and the size of the fractions does not exceed 5 millimeters.

The functioning of drainage pumps when transferring wastewater having an elevated temperature is limited to a time period - information on this is contained in the operating instructions of the manufacturer. The fact is that the cooling of the engine of the unit is due to the return of heat to the pumped liquid.

  Criteria for selecting drainage pumps

There are several rules that should be followed in the case of the choice of apparatus:

   It is necessary to take into account the type of pumped liquid - here pay attention to the size of fractions in dirty water. It is necessary to familiarize yourself with the main parameters of the drainage unit in order to stop your choice on a certain model.

First of all:

• pressure - this value for medium-capacity equipment is 7-10 meters. In some models it reaches more than 30 meters. The data on the pump head depends on the distance to which the liquid is to be dispensed;
• performance - the choice depends on the volume of the tank. For example, for a capacity of 40 "cubes" there is enough apparatus with 10 cubic meters per hour. For industrial purposes, more productive pumps are needed - about 100 m³ / h and more;
• depth of immersion apparatus - the maximum given value reaches 5 -15 meters, and the minimum - 0,3 - 0,9 meters.

   It should be remembered: when the unit is running, its pumping part should be under water.

In addition, you need to know, from what moments depends on the life of the pump:

• the quality of the materials from which the elements of the equipment are made;
• temperature of pumped dirty water, it should not be more than + 50 ° C;
• diameter of the drainage passage;
• presence of protection against possible overheating. Usually a thermal relay is built into the pump (it will turn off the power if the temperature of the liquid becomes critical) and a float switch.

  Repair of drainage pumps

   When the drainage pump breaks down - malfunctions are eliminated after finding out the cause of the breakdown.

Most often it happens:

• improper operation when the operating parameters of the apparatus are exceeded;
• a long period between maintenance;
• long-term operation of the device in "dry" mode;
• very large solid inclusions in the pumped liquid (then the drain pump does not pump water);
• poorly produced pump mounting;
• production defect.

When the device is inexpensive, the drain pump is dismantled and it is repaired by one's own hands, provided that you have the skills to handle such units.

If there are first signs of malfunctioning submersible pump, it is necessary to check the operability and condition of individual elements:

• the piston must be flexible and can not be mechanically damaged;
• it is necessary that air blown on the site of the intake of liquid freely pass on both sides;
• the optimal distance between the piston and the coils of the electromagnet is from 0.4 to 0.5 centimeters. If the gap is greater, the coils are beating, and when less - the motor overheats;
• between the valve closing the inlet openings and the housing, the gap should be between 0.7 and 0.8 millimeters.

Often, the cause of poor operation of the equipment is not the breakdown of individual elements, but the voltage drop in the electrical network. Before dismantling the drain pump and starting to repair it yourself, it is necessary to check the voltage in the network, which should be 200-240V. If this parameter is normal, you can start disassembling by applying special notches on the areas to be joined.

If the drain pump does not pump, which is in working order, the possible reasons are as follows:

• the air intake got into the water intake part;
• insufficient depth of immersion of the unit;
• the water intake element is not covered with liquid.

   To eliminate the shortcoming, it is necessary to load the equipment, until the water completely covers the water intake part. Pump should be tilted to eliminate air-cork.

Only with the condition of timely elimination of malfunctions in the operation of the drain pump will it operate for a long time without serious problems.

A) Pump starter does not work
Before analyzing the reasons for the water flow in the hydraulic circuit, it seems useful to consider the most obvious malfunction: the pump starter does not work.
The electroscheme of most pumps is quite simple. On small pumps with a single-phase drive motor, even starters are sometimes absent: the engine is started with a conventional starting capacitor (PSC circuit, see section 53).
For large pumps, three-phase current motors are used and the application of the starter becomes necessary. On the circuit diagrams, the "start-stop" button, the fuse (thermal relay) and finally the coil of the starter "Pump of ice water" (PEG).
If the actuator does not work, the defect is detected relatively easily and quickly (see Section 54). It remains only to determine why this or that safety device has worked, to fix the malfunction and to try to make it so that the defect no longer repeats.

B) The starter is closed, the pump "buzzes", but does not start
The three-phase motor starter has tripped. The engine starts to "buzz", but does not rotate. There can be several reasons: either the pump has jammed, or the problem is in the engine itself, or the voltage on one of the phases in the mains has disappeared. In the latter case, the fuse (thermal protection relay) very quickly cuts off the voltage, otherwise the engine will have a high probability of "giving the soul to God".
In order to detect a phase failure or so-called "phase skew," press the "Stop" button and check the voltage for each of the phases at the input terminals. Never check the voltage at each phase with respect to the neutral wire (if the two phases are the same, then you will not be able to detect anything!). Check the voltage between phases L1-L2, L1-L3 and L2-L3. All voltages must have the same value. Otherwise, the cause of the malfunction is in the power supply.
If the voltages of all three phases are normal, check that they are present at the input of the fuse box (key 2). If there is no voltage at any phase, either the wire is broken or the connection is poor. Similarly, check the output voltage from the fuse box (key 3). Here the problem can be either in the fuse blown, or in the fault of the disconnector (bad contact). These faults are discussed in detail in Section 55.
Finally, check the voltage at the input of the starter (key 4). Here is the same:
either the wire is broken or the terminals are tightly clamped.
If the voltage is normal at the input of the starter (item 4), before starting further checks, disconnect the motor winding from the terminals pos. 7 at the output of the starter.

Disconnect the motor winding from terminal box   (key 7 in figure 92.3), then close the pump switch (key 1) to activate the starter. In this case, since the motor winding is disconnected from the starter and the starter has tripped, a voltage must appear on the terminals (key 7).
If this does not happen, check the voltage at the terminals (item 5 in figure 92.2) to identify possible problems in the terminal box, on the connecting wires between the starter and the terminal box, as well as in the power circuit of the fuses or the starter.
  If there is voltage on the terminals (key 7), the fault is caused by either a break connecting wires   between the engine and the terminal box, or by the motor itself (see section 62. and also section 53), or by the fact that the pump does not allow the motor to rotate (because, for example, it completely jammed).
If the drive motor of the pump is a single-phase motor with a starting winding, and this engine "buzzes" but does not rotate, then either the starting capacitor is faulty (see Section 53) or the pump is jammed.
In those cases where the drive motor allows the speed to be changed and the regulator is set to the minimum speed, check if the engine has enough power: the motor torque must always be greater than the pump resistance moment (see section 55).

B) The starter is closed, but the pump does not rotate

First check the motor supply voltage. Make sure that fuses   or the switch (item 1 in figure 92.3) are closed, then check the voltage at the terminals (key 7). If there is no voltage, check the power circuit, just as we described above.
If the voltage at the terminals (key 7) is, measure the current in each phase with a clamp meter! Measuring the current absorbed by the motor is the most reliable way of controlling the operation of the pump if it is rotating (see Section 93.2).
Indeed, the pump impeller may well remain stationary (gauges installed at the pump outlet will not change their readings after the engine starts), while the motor will draw current from the network (for example because the impeller scrolls on the axis). Note that in this case, the current consumption of the motor will be very low, and the pump will emit a characteristic "bounce" (as if pans in the kitchen clatter).
Check connecting wires   between the starter terminal box and the motor winding (motor terminal box) and the voltage on the motor terminal box (item 8 in Figure 92.3).
If the three-phase AC motor is designed to operate at two mains voltage values, check the motor winding connection diagram (see section 62.1). In any case, do not be too lazy, remove the terminal box cover and look at it from the inside: as a rule, on the inside of the cover the connection diagram of the windings is given.

Note. Some small single-phase motors are equipped with a built-in thermal protection ("klixon" - "clicheson" relay), which disconnects the motor from the network when the temperature of the winding rises to the maximum permissible value.
At this time, the current consumed by the motor is zero, although the supply voltage at its terminals is present, and the motor housing is hot by touch. Remove the power from the motor (the coil will soon cool down) and check the ease of rotation of the shaft (see Figure 92.4).

D) Mechanical malfunctions
Depending on the design of the pump (see section 90), a wide variety of mechanical faults can prevent the free (easy) rotation of the shaft.
Dirty water with aggressive impurities or scale causes the scum, dirt or other impurities to clog the space between the rotor and the stator in the pump with the "flooded" motor rotor and the pump rotor "wedges". In addition, this dirt can cause seizure of bearings or sealing glands. The impeller can be jammed with a foreign body (a rag, forgotten in the pipeline during installation, deposits of scale or dirt, etc.).
Therefore, first of all, you should make sure that the axis of the motor is freely rotated by hand without any effort.
  On pumping units with a coupling (item 1 in Figure 92.4), it is very easy to make sure that the shaft rotates freely. Turn off the motor power, grasp the sleeve sleeve by hand and try manually turning the shaft. In this case, you will also be able to verify that there is no excessive play of the clutch, evaluate the degree of wear and check the stiffness of the clutch. Also check the oil level (item A). If there is a need for oil refilling, use only the brand recommended by the pump manufacturer.
  For a pump with a "dry" rotor (item 2 in Figure 92.4), remove the supply voltage from the motor and use a screwdriver or other suitable tool to turn the motor axis (coin, hexagon, etc.) and check the ease of rotation .
Some models with a "submerged" rotor of the engine (item 3 in Figure 92.4) are equipped with a screwed stopper with a plate shank (which sometimes serves as a drain cock) mounted on the shaft end.
On other models, you need to remove the sight glass to get to the shank. As a rule, when removing the sight glass, the pump does not lose its tightness.

The jamming occurs mainly after a long pump stop. The most common way to eliminate jamming is using one of the methods described above. Otherwise, you have to close the shut-off valves (if only they were sealed), and then disassemble the pumping unit to get to the impeller and turn it along with the axis.
Further, after starting the pump, it will be necessary to make sure that the current consumed by the engine does not exceed the value indicated on the nameplate of the engine.
In the example in Fig. 92.5, the motor is supplied with a voltage of 380 V, at which the nominal value of the current consumed by the motor must in no case be higher than the specified value. In addition, the fuse must also be set to a maximum current value of 1 A (see Section 55).

In pumping units with a coupling (see Figure 92.6), the excess of the nominal current consumption may be due to excessive tightening of the gland seal (see Section 90).

After replacing the sealing cord or during the gradual tightening of the stuffing box, always check the amount of current absorbed, not exceeding the value indicated on the nameplate of the engine.
During normal pump operation, the current consumed by the motor is mainly dependent on the amount of water flow through the circuit. The rated current indicated on the nameplate of the engine is extremely rare, except when the temperature and water pressure in the circuit approach extreme.
Never adjust fuses by the amount of current,
which is the value indicated on the motor nameplate.
This rule is valid for all electricity consumers (pumps, fans, compressors, etc.).

Drainage pumps   widely used in various spheres of human life.

With their help, water can be supplied from open sources (pools, ponds, etc.) and closed (well wells) sources.

They are indispensable in the flooding of living quarters as a result of accidents or natural disasters.

Numerous manufacturers of this equipment, among the main advantages of their products, are reliability and long service life. In most cases, this is true, but nevertheless, like any other equipment, drain pumps need maintenance and can fail for a number of reasons, including the following:

• violation of the rules of installation of equipment;
• violation of the rules and norms of operation (overload or prolonged work in the "dry");
• untimely or unskilled maintenance   pump;
• pumping liquids with solid inclusions of large size.

Consider the symptoms of the most common breakdowns of drainage pumps:

1. The pump hums, but the water does not pump.

The reasons for this "behavior" of the pump can be as follows:

• the shock absorber mount on the pump stem has loosened. This is one of the few situations where the repair of a drain pump by one's own hands can not be performed without special equipment and without practical skills. It will be necessary to disassemble the body and tighten the two fixing nuts. Upper counter;
• the valve is damaged. Replacing the valve at home is difficult to produce. It is advisable to contact the service center;
• the pump stem is broken. In this situation, repair of the drain pump is almost impossible. It's easier to buy a new pump.

1. When the pump is turned on, the cables "fly out" and the cable melt. The winding burned. With such a breakdown, an independent repair of the drain pump is not possible. Elimination of such a malfunction must be carried out in specially equipped workshops, because The replacement of the armature winding must be accompanied by a thorough testing of the pump.

Important! The listed faults are basic for the vast majority of drainage pumps. Any other failures in the pump, somehow "flow" from them.

Saving or quality?

Of course, in this version the question sounds too categorical, but, in the overwhelming majority of cases, choosing between self-repair equipment and contacting the service center, we choose one of the named priorities. Modern submersible pump is a complex electronic-mechanical unit, an intervention in the work of which requires the performer special knowledge and practical skills.

How to choose a drain pump read.

Service centers have at their disposal special equipment, the use of which allows to significantly optimize the process of testing and repair of pumping equipment.

Advice! Unqualified repairs can entail costs significantly higher than the cost of repairing the drain pump.

The drain pump is an integral device in the everyday life of any inhabitant a country house   or cottages, because with his help you can provide a full water supply site (watering the garden and garden, water supply of the house, etc.) or drainage of waste water. Submersible or surface devices are considered durable and reliable instruments, but, like any other technique, they are not permanent. Therefore, in this article we will consider all possible malfunctions and self-repair of the drain pump.

Common Faults

Buying even the most expensive station can not be sure that once it does not happen a breakdown, and most often the equipment can fail for the following reasons:

• initially wrong installation of the device;
• absence of contact of the pump with water, that is, work "on dry";
• unstable food, namely - frequent drops and drawdowns of the network;
• contaminated water with a high content of abrasive particles;
• the power cord is damaged or improperly installed.

Often, equipment breakdowns are very commonplace, and due to their high cost, repairing the drainage pump with their own hands can be a good alternative to saving the family budget.

The most common failure of pumps is the failure of the pressure switch or accumulator, due to the absence of a filter. There are also cases of defrosting or the absence of a grounded loop on the device casing.

At all. all possible failures are divided into electrical and mechanical. For example, strange foreign sounds at start-up or during operation of the device testify to mechanical breakdowns. Such damage to the device can be completely corrected independently, but electrical defects can lead to a complete stop of the device and subsequent repair only in a specialized service center. Although the breakdowns on the electrical side are very common, for example, a safety switch has tripped, or the supply cable has disappeared.

Preliminary inspection of the drain pump

Before you begin repairing the drain pump yourself, you'll have to inspect it or even disassemble it. If the visual inspection has not yielded any results and everything is in order with the device, and you checked the voltage in the network and it corresponds to 200-240 V, you should disassemble and check the main components for the following faults:

• No deformation and damage to the piston;
• Make sure that there are gaps between the magnetic coils and the piston, which should correspond to 4-5 millimeters. A smaller distance will lead to overheating of the devices, but more will entail a battle of coils;
• Presence and free passage of air from the intake side of the pump;
• Inlet openings must have a gap between the body, namely at the place of installation of the valve. For a full-fledged supply of water, a gap of 7-8 mm is needed.

Popular pumps and problems with them

When choosing a drainage pump, it should be remembered that there is nothing eternal and even a high-quality apparatus can one day break down. Having considered numerous reviews and interviewed a lot of experts in the repair of equipment, several distinguishing features of each device were highlighted:

1. Domestic drainage pump "Malysh"   is very popular. The reason for such fame is the low cost of the product itself and the acceptable price for spare parts for repairs. Also, craftsmen easily repair their own. The most common malfunction of pumps "Kid" is the rupture of the swinging diaphragm. Symptoms of a malfunction are strong hum and lack of water pressure. Repair is performed only by replacing the torn membrane with a new one.
2. For pumps "Dzhielek" such problem as loss of engine oil is inherent. The repair is carried out in the service center at a similar factory. There is an opinion of home-owners that the liquid from the engine can be replaced with glycerine or transformer oil. But this information is not verified, and such an alternative can lead to a complete breakdown of the pump.
3. Drainage pump "Water meter"   is famous for its reliability and most often the breakdown of this equipment is associated with improper use. Like other apparatus, "Vodomet" does not tolerate abrasive particles, such as silt and sand. If this happens, then you have to change the whole pumping part.
4. Grundfos drainage and faecal pumps are very reliable, with most models having improved motor thermal insulation and built-in valves. Since the devices operate in an aggressive environment, the pump should be removed from time to time and all seals replaced.
5. Surface and submersible models of pumps "Brook" produce according to the highest European quality standards, but they have one significant drawback - it is overheating. According to the statements of the manufacturers, their products are capable of continuously working for 7 or more hours, but as practice shows, this indicator is 2-3 hours after which the pump should "rest".
6. As in the drainage, and in the fecal pump "Aquarius" there are problems with overheating of the motor, especially when used in small wells or wells. If an inexpensive model of a pump breaks, it is easier to replace it with a new product, since repairs cost half the cost of equipment.

Operation of automatic devices at pump start-up

Knockout of plugs when the pump is switched on indicates a short circuit in the circuit. Consequently, the closure occurred in the power cable or in the worst cases in the anchor of the device. To determine where the drain pump broke, you'll have to get a tester or a multimeter. When the device is cured from the well, washed and dried, a visual inspection of the cable is performed, and in case of not detecting the problem, a test by the tester.

Advice! When repairing surface devices completely to disconnect it is not necessary, the main thing, turn off the power and make sure there is no pressure in the water supply. It is important to know! Replace the wire sometimes can be problematic, because in some submersible and surface models of pumps have the cables embedded in the casing.

If the cable is full, then only the version with the burnt anchor remains, but in this case it will be extremely problematic to do without the services of the service center. As an option, he will ask for help from a good electrician who can rewind the armature winding.

Noisy, but not shaking

Another common problem that a drain pump may have is noise during operation and weak or no water pressure at all. The cause of pump breakage may be an unscrewed shock absorber, or, rather, weakened two fastening nuts. Also, the faulty valve may become the worn out valve or its full rupture.

To solve the problem with the membrane, Naos will have to be disassembled to reach two nuts located behind the membrane and tighten them to the stop. If the device has been in the water for a long time, the screws that tighten the body can be rusted with a WD-40 liquid and try to unscrew it after a while. If after these manipulations the bolts still do not open, they will have to be cut off by the Bulgarian.

The problem with the valve can only be solved with a complete disassembly of the device and subject to the availability of repair kits. Otherwise, you can not do without the services of a service center.

Vibration and overheating of the pump

If the drain pump is not equipped with a special thermostat, which in case of overheating disconnects the device, it will have to be carefully monitored so that the device does not work "dry" for a long time. Since the cooler of the pumps is the liquid that it pumps and, having worked for a long time without water, the pump casing can overheat. Due to overheating, a magnet fixed in the casing with a special epoxy adhesive can move and jam the transfer piston.

After detaching the magnet in the pump, a chain reaction occurs, which leads to breakdown of all electronics and mechanics, and, consequently, the pump becomes just a heap of debris. According to experts, such a breakdown is the most difficult in terms of repair and often is economically impractical, of course, if you catch yourself in time and find out a breakdown in time, you can get by with "little blood", and, after giving the device to a service center, the magnet will be replaced, and damaged parts will be replaced.

Of course, you can try to repair the drain pump yourself, but there is a big risk of doing something wrong. For self-repair, the device is completely disassembled and the magnet is carefully removed. Then, a shallow longitudinal incision is applied to the magnet and pump body using a grinder or other device. And the final stage is the application of a new epoxy glue or glass sealant, as well as reassembly and replacement of worn parts.

Weak output pressure

Submersible and surface pumps   often have such a breakdown as weak output pressure. The reasons for such a breakdown may be several:

• Clogged filter. If the filter grid is clogged, the water pressure may drop or the supply may stop completely. Symptoms of clogging are the operation of the device in the load and increase in noise, and the motor may overheat.
• Surface stations can have damaged pipe or weakened clamp, as a result of which air is sucked in and the pump is not able to lift water from the well. The solution of the problem is trivial - check the condition of suction pipes and clamps.
• If everything is in order at the pump inlet, then only variant with a small stroke of the vibrator. This problem is solved elementary, you need to disassemble the device and put a washer on the vibrator rod.

Advice! It is imperative to check the condition of the membranes and seals, they must be complete and without damage.

Perhaps, it is necessary to put a few washers, all this is determined by experience.

Conclusion

In the article, we listed the main malfunctions that have submerged and surface drainage stations and possible ways   their repair. For self-repair, you need to have at least initial skills in working with devices, otherwise it's better to contact the service center. After all, what is a drain pump for? Properly ensuring a comfortable life in a country house   or the country house. But the repair and maintenance of such devices should be handled by specialists. If you like to pick your own hands in various devices, then inexpensive models will be your best option, but for repairing expensive devices it is better not to undertake.

According to statistics, submersible drainage and fecal pumps are broken in 95% of cases by the fault of the consumer due to improper operation, and only in a small number of cases there are any other reasons (factory marriage or some unforeseen factors).

You often hear from customers that:
- All pumps are bad (and especially the one that was sold to me - initially a low-quality pump, probably the "left" Chinese) ...
- we did everything right, according to the instructions, and the pump somehow burned out ...
- we put the automatic defense, which was supposed to turn everything off ...
- and in the pump, in general, the passport is thermal protection (if it is at 220V), but it did not work ...
- etc. etc.

Let's try to figure it out.

1. Regarding the sale of substandard pumps:

No trading company will sell deliberately low-quality goods, because otherwise it will be necessary to constantly conflict with consumers, repair the goods at their own expense and bear the related costs, not to mention the fact that the image of the company suffers, etc.
The overall quality level of pumps produced in the 21st century is consistently high, with very few exceptions. The firm "PUMPS AMPICA" does not sell poorly proven models, excluding them from its range.
Thanks to many years of experience in pump sales, we have developed a stable range of quality, time-tested models from a variety of manufacturers.

2. Concerning the manufacturer:

There is no market for quality European submersible pumps at a price below 7 ... 10 thousand rubles.
All that is sold below this price is made in China. Many European companies only stick labels and pack Chinese pumps.

At least 70% of European companies produce their pumps in China and sell them under their own brand. This does not mean that they are bad. It is impossible to collect quality products "on the knee". Modern production is almost completely automated.
It is extremely difficult to spoil anything in the process of assembly. In addition, the time has already passed when China did not monitor the quality of products. This is an entire industry and no one will lose a huge sales market in Russia.
Naturally, buying a submersible pump in a large supermarket for 500 ... 900 rubles, you should not count on its trouble-free operation during the rest of your life.
Such goods are sold as "zavlekalochki", as accompanying. Everyone understands that the buyer will not be due to 500 ... 900 rubles to go to the service center to repair the pump to the other end of the city (or send it by mail to the service center, sometimes this is a "pleasant" surprise for the buyer).
Because of such "superproducts", confidence in Chinese goods is lost (but, we repeat once again that in gross stores only gross sales are important).

Summarize:
- there are no cheap European pumps,
- 2/3 of European pumps are actually produced in China and you will pay half the price only for the brand of the manufacturer,
- do not need to buy pumps in large supermarkets for 30 cents. The proverb about "cheap cheese" has not been canceled.

3. We (customers) did everything correctly, according to the instructions ...

Half of the people who "did everything according to the instructions" did not open it. It is enough to ask 2 questions to determine this.
Do not be lazy to read the instruction manual of the pump. It takes a little time, but it gives an idea of ​​what is good, what's bad for a pump.

4. We had a machine gun ...

The automatic circuit breaker is installed by a conventional one, which does not track small current changes. Its power is chosen 2.5 times higher than the power of the electric motor of the pump (because of the large starting current). While this machine "swings", the pump is already overheating and will fail.
In a mind, you need to put not an ordinary automatic machine (which, basically, only from a short-circuit in the network saves), but an automatic motor protector. it special device, which allows you to accurately set the working current of the motor and tracks its slightest increase due to the wedging of the pump shaft.
In this case, the motor protection circuit allows exceeding the set value of the motor current at the time of its start.
Usually we offer automatic protection of the engine manufactured by ABB MS series. These motor protection circuit breakers are more expensive than conventional network automatic machines, but they reliably protect the pump motor from overheating.

Conclusion:
- for the protection of the motor, it is required to install the MOTOR PROTECTION AUTOMATA, and not the usual network circuit breaker, you do not need to save on this,
- You should read the instructions, especially the places that are highlighted - there's just about all this written.

5. Regarding thermal protection:

Thermal protection is built into the winding and represents a relay that switches off the motor power when the heater is heated.
It should be understood that every time the winding overheats, its insulation is fused, that is, irreversible changes occur. After some time (with the next overheating), the insulation must be completely melted in some place and a short circuit of the winding will occur, which will lead to the failure of the electric motor.
That is, thermal protection is not a panacea for all troubles, but only emergency protection, which is capable of saving the electric motor several times and nothing more.

6. Work without water.

The submersible pump motor is cooled by the pumped liquid. Submersible pumps are of two types: with jacket cooling and without it.
Pumps with a cooling jacket can not work fully immersed in the liquid, because water will pass through the surrounding pump housing and cool the motor.
Pumps without cooling jacket should always be completely submerged in the pumped medium.

Hence, there are 2 basic errors when installing the pump, which lead to overheating and failure of the motor:
- operation of the pump in water, with a temperature higher than indicated in the passport for the pump (in the normal version up to + 35 ... 40 ° C, and up to + 60 ° C in heat-resistant version).
This is often the fault of public service employees in the event of accidents in the hot water supply system.
When a pipe breaks through hot water   requires pumping it out of the wells, to carry out repairs. External pump does not work, because just does not suck hot water   because it boils in the suction pipe and you have to use a submersible pump, which in a few minutes "dies" from overheating.
There are solutions for this problem, but here we will not touch them.

The operation of an incompletely submerged pump or pump without water. And in one and the other case the motor overheats and breaks down. The usual automatic defense does not track this.

Solution:
- installation of the pump in the pit,
- use of automatic water level monitoring (for example, float switch).

A common mistake: the installation of small capacity in a large area capacity.
In this case, the water level during evacuation decreases very slowly, and the pump can remain for a long time not completely immersed in the liquid.
For example, such a mistake was made by our customer when installing the pump in the repair dock, where it was planned to pump out the water after installing the vessel in it.

7. Operation of the pump outside the operating range of delivery and head.

Let's analyze on a concrete example: the drainage pump GNOM 40 / 25Т.
The pump stood in a foundation pit and fed water to a height of 7 meters through a 100 mm hose. Then came the pouring of water on the ground.

Inspection of the pump revealed that all 3 phases were burned in the pump motor, indicating that it was overheated.
The recommended pressure of such a pump, according to the passport, is 18-25 meters. That is, it is the range in which the motor operates without overload.

When the pump is operated with a head of 7 meters, the pump operates in the feed range, which is significantly higher than the operating range (the lower the head, the greater the supply in any centrifugal pump). In this case, the operating current in the pump windings is greatly increased, which leads to overheating of the motor.
When operating outside the recommended pressure range, install a valve at the pump outlet and set the supply so that the operating current in the motor windings matches the one specified in the passport (in this case 12.5 A) + install the motor protection unit.
Otherwise, the pump will operate with overload, and the motor may be damaged.

When running the pump with a head of 7-10 meters, the most optimal use of the GNOM 53-10T pump. In this case, feed adjustment is not required.

As you can see from the above example, you do not need to take a pump with a "margin" for pressure, because this can lead to its failure (although it seems that once the pump delivers 25 meters, then when filing for 7 meters, there should not be problems).

8. Pump operation on the closed valve / work through the narrowed pipe

Sometimes it is required to drain sewage into the sewage system, in which there is some pressure (the so-called pressure sewage system). In this case, it is required to select a pump whose pressure will be 0.5 atmospheres higher than the pressure in the sewer.
Moreover, the pressure at the entrance to the sewer pipe must take into account the head loss from the pump to the point of entry into the sewage system.
If the pressure at the inlet to the sewer is not sufficient, then the liquid from sewage pipe   will flow through the pump into the septic tank.

To prevent the flow of liquid, in this case, it is necessary to install check valve.
If the pump pressure is incorrect (less than in the discharge pipe), then when the pump is turned on, it will work continuously on the closed line, which will lead to overheating and failure.

Often, customers save on pipes and buy pipes of smaller diameter than required. This leads to:
- the pump performance decreases (it can start to work outside the operating range), which leads to its overheating,
- the pipe may become clogged, which will cause the pump to work on a closed pipeline, that is, work with overload, and, consequently, overheating of the electric power and its failure.

Some manage to use fecal matter on a pump that can pump particles up to 50 mm with a pipe of 32 ... 38 mm and then wonder that for some reason the pipe is clogged and the pump is out of order.
If you really want to save on pipes, you can put a fecal pump with a chopper.
In this case, the pipe will not be clogged by coarse particles (but the pipe diameter must still be calculated in advance so that the pump does not work with overloading).

The diameter of the pipe depends on the pump's capacity and length.
Below is a table on which you can determine this:

9. Pump operation with liquids of high density and viscosity.

When working with liquids that do not correspond to the passport data, the electric motor starts to work with overload, which leads to its overheating. Then everything follows the scenario described above.

10. Work with highly abrasive fluids; a large number of large solid particles.

When pumping fluids with a large amount of abrasive, the shaft seal quickly wears out, which causes liquid to enter the motor housing and cause it to malfunction.

Often, reading in the instruction that the pump can pump liquids with particles up to 35 ... 50 mm (most household faecal pumps), consumers think that such particles can be stones, nails, reinforcement, pieces of cement, etc. and in large quantities. In fact, this is not the case at all. If such particles constantly fall, then this will lead to the destruction of the impeller and the compaction. Such pumps can pass large particles, but mostly soft.
Often enough building organizations, digging foundation pits, save on industrial equipment and buy household pumps for pumping water (why, it will be clear below).
Ends it is always the same: bring pumps that are completely clogged with sand and stones, pumps with broken impellers and housings.
And, as always, we hear the same thing: the pumps are bad, they immediately burned out, etc.

And now, for your information: special pumping pumps are required for pumping out from pits. They are made of special wear-resistant steel and have electric motors of increased power.
The prices for such pumps start from 120 000 rubles (who is interested, you can see on our site in the section "Sand and slurry pumps).
And they buy pumps, for the same purposes (especially economical builders), for 10-20 thousand rubles.

11. Frequent on / off switching of the pump motor.

Any electric motor at power-up, consumes current several times higher than the working one. Therefore, there is a limit on the number of pump starts per hour (the more powerful the motor, the fewer starts per hour it allows).
For comparison, we give the table:

A common mistake in installing a pump is that users reduce the length of the float switch cable so that it turns on "more often". Sometimes it turns on so often that it exceeds the permissible limits, which leads to overheating of the windings and the pump's failure.
Alternatively, the pump is lowered into a narrow well in which a high-power pump is installed. If a lot of water is drained into this well, for example, with a prolonged shower, the productive pump quickly pumps out the water, turns off, then the water quickly fills the narrow well, the pump turns on, etc. In this case, the permissible frequency of the motor starts to be exceeded, which will lead to its failure.

It happens that the pump is in a narrow well and pumps the water along a long pipe up the slope. If you do not install a non-return valve at the pump outlet, this will cause the pump to pump out water and turn off (if equipped with a float). After that, the water from this pipe because of the slope, will drain back into the well and fill it, which will lead to the inclusion of the pump. This process can be repeated until the pump burns down.
And naturally, we will hear the familiar phrase: "the pump is bad."

This fault is sufficiently well revealed when the pump is inspected - the starting winding burns at 220V pumps.

12. Pump operation under reduced voltage; voltage surges.

When the pump is operated at a lower voltage (which differs from the set value by more than 5%), the operating current in the motor windings greatly increases, which leads to its overheating.

This situation can arise for two reasons:
- problems in the power network (in our country half of the country at rush hour the voltage in the network is lowered),
- the use of a long power cable, without the correct selection of its cross-section, depending on the length and power of the motor.
If you put a long cable of a small cross-section, then because of the increased resistance, the voltage that reaches the pump motor can be significantly different from the supply voltage.
- the electric motor may fail due to power surges in the network.
For example, if you have a 220V network in a dacha, and next to you, the handicraftsman continuously welds something with electric arc welding, while he is sitting in a different phase, then at the time of his miracle operation (well, if it is factory production, not manufactured by the skilled craftsman) there are very large voltage fluctuations. All this together can lead to failure of the pump motor.

13. Pull the submersible pump to the surface by the power cable (behind the float).

This is one of the most common ways to "kill" a pump.
When pulling by the cable, there is a violation of the tightness of the cable entry connection to the motor housing. This leads to the ingress of water into the motor and its failure.
It also happens that the cable is not sealed (for example, it was dropped on the power cable when carrying the pump).
Outwardly this does not appear in any way, but, over time, water through the cable gets into the electric motor and disables it.

14. Use of poor-quality start-up equipment.

We had one client who "killed" 2 pumps at an interval of one day. In the event of a defect, it was found that the electric motor operated in 2 phases instead of three (two windings of the electric motor were burnt).
When the first pump was brought. we strongly recommend checking the pump starter. But, as usual, it was said that we ourselves all know, etc. and the like, and you have "bad pumps".
After the second pump was brought with the same malfunction, our customers were smart enough to replace the starter (the price is 500 rubles). After that the problem disappeared. That's because of the reluctance to listen to the advice of professionals, you can save 500 rubles on the starter and pay for repairs of 30,000 rubles.

15. Connecting the pump to electricians who do not understand what is going on.

Now there are many incompetent "workers" who do not understand anything in electrical engineering, but, nevertheless, they undertake to connect any equipment. Savings can come not only with the loss of money, but also with injuries and a fire.
Recently, one such person called and was unhappy that he did not have a 3-phase pump that does not work with a float switch. As it turned out, to turn off the pump, he broke one of the phases of a three-phase electric motor.
It's good that the owner of the pump suspected something was amiss and called us on his own.
Before the "murder" of his pump remained very little ...

16. Work in aggressive environments.

Many people think that if the pump is made of stainless steel, then it can be shoved into any container and shake any chemistry. Usually, this belief ends after a few minutes of running the pump (the last minutes in his life).
Undoubtedly, there are such pumps, but only they cost from 150,000 rubles and more.
The pump has many more parts that must be able to withstand the aggressive environment. Conventional pumps are not designed for this purpose.

We want to sum up all of the above:

1. All the reasons given in this article for the failure of the pump were real.
2. To design the pump, it is better to consult with specialists and answer ALL the questions they ask, no matter how "dumb" they do not seem to you.
3. ALWAYS install the motor protection.
4. If voltage is applied to the installation site, install a voltage regulator.
5. The pump must only be used for its intended purpose.
6. Where higher reliability is required, it is worthwhile to complete the pumps with control and protection cabinets.
The organizations that managed to persuade to equip the pumps with control cabinets, with all possible protections, made sure that not all pumps are "bad", but only those that are exploited by people who do not follow the equipment and who do not care what happens to him.
Automation monitors various critical situations and has protection from the "fool".

We hope that this will help someone to make the right choice of the pump, and someone will survive the failure of their "faithful assistant" and not blame all the blame on the sellers and the manufacturer.