Centrifugal pumps without motor with open shaft Pedrollo FG series. For people who are far from any technical structures, we will conduct an easy "educational program"

The rapid development of the electrical industry marked the end of the era of steam engines and the beginning of the widespread distribution of electric ones. Electric pumps are one of the most sought after mechanisms of our time. Here and below under the term "pump" the whole mechanism is meant as a whole - the engine, the transmission mechanism (reducer or other device that performs its functions) and the executive body (impeller, blades, piston).

The electric motors underlying the pumps are very high efficiency(83-95%), relative simplicity of design, versatility and high reliability. The type of engine used and its mode of operation to a large extent determines the final characteristics of any electrical mechanism.

In most cases, if not special requirements, apply asynchronous motors with squirrel-cage rotor. Schematically, such an engine consists of a housing in which a stator (stationary part) with a winding and a rotor (rotating part) are located. The voltage applied to the stator winding creates a rotating magnetic field, the interaction of which with the rotor winding causes the latter to rotate. The winding in electric motors is a specially wound on metal carcass copper wire coated with insulating varnish.

And if the electric motor is the heart of the electric pump, then electricity is the soul. Without it, the pump simply will not work. Electricity is characterized by quality, that is, all its parameters must correspond to the calculated ones. In the case when any parameter goes beyond the limits set by the standard, the pump operation mode also changes. The main characteristics of electricity are the values ​​of voltage, its form and frequency (for alternating current). Each country has its own standards for the above parameters. Voltage is an electromotive force, a potential difference, or, simply put, it is the energy that is released when a charge moves between two points.

According to GOST, voltage (U) of 220 Volts + -10% is accepted for the CIS countries. Frequency (Ω) determines how often the polarity of the voltage changes per unit of time. Standard value is 50 Hertz +-1%. The main parameters of pumps are head, flow and duty point, which combines these two parameters. The pressure is the pressure of the liquid created by the pump, and the flow is its amount pumped per unit of time. And since the principle of operation of the entire mechanism is to convert the rotational energy produced by the engine into work performed by the executive body, it is important to ensure the stability of the calculated rotation speed. One of the most important characteristics of an asynchronous motor is slip. Slip is the difference in rotational speeds magnetic field created by the stator winding and the rotor itself. The greater the load or the lower the voltage, the greater the amount of slip.

The relationship between the rotor speed and the mains voltage is expressed by the formula:
N=Nsync*(1-Kload*Ures*Snom); where:
"N"- the resulting speed of rotation of the pump motor,
"Nsync"- synchronous rotation speed,
"Kload"- engine load factor,
"Ures"- the ratio of the squares of the rated voltage to the actual voltage,
"Snom"- slip value in nominal value.
This means that when the mains voltage decreases below the nominal value, the speed of rotation of the motor rotor and, as a result, the overall performance of the pump also decreases. It is important to note that this corollary is true for pump motors operating at full load. If the pump is selected with a "margin", then the effect of voltage reduction is not so noticeable.

Video clip: "Operation of the frequency converter Speeddrive"

The next negative manifestation of the decrease is the heating of the windings. With a decrease in voltage below the permissible value by 1%, the magnetic flux in the motor decreases by 3%. In general, for engine power, you can use the formula:
P = U*I, where:
"P"- engine power,
"U"- mains voltage,
"I"- the current consumed by the motor.
Therefore, while maintaining the value electrical power motor and voltage drop, the current consumed from the network increases. Exceeding the current value in excess of the calculated parameters causes increased heating of the windings and, as a result, a decrease in the life of their insulation. In some cases, engine failure is possible. Increasing the voltage above the nominal value reduces the life of the motor and, if excessively overestimated, "electric breakdown" winding insulation. In this and the above cases, we say that "engine burnt out".

The speed of rotation of the magnetic field and, as a consequence, the speed of rotation of the motor rotor depends on the frequency of the network. This dependence is described by the formula:
n= 60*f / P, where:
"n"- synchronous speed of rotation of the magnetic field,
"f"- mains frequency,
"P"- number of pairs of poles of the stator winding (mechanical parameter).
Therefore, with a constant number of pole pairs, any change in frequency directly affects the rotation of the motor and the mechanical power it develops. Vibratory or screw pumps are a special type of pumps. Their design does not have an engine in the classical sense, so breakdowns caused by over or under voltage appear a little differently. If such a pump is installed in a well or well and operates at normal voltage in its nominal parameters, without a "margin" in power, then if the voltage drops, it will not be able to raise water, which for some models is fraught with failure. And when the voltage is overestimated, the intensity of the movement of the pumping membrane increases and the mechanism gradually breaks itself. The same effect is manifested, respectively, by lowering and increasing the frequency of the network.

A high-quality pump is purchased taking into account long-term operation without breakdowns - "set and forget". The price of such a solution is usually appropriate. Therefore, the right decision would be to take measures to protect the pump from possible changes in the parameters of the electrical network. One of the options is to connect the pump to a device that monitors and regulates voltage - a stabilizer. The stabilizer is selected by power with a 20-30% margin. The margin is necessary due to the higher power consumption at the time of each start of the electric motor. Wider pump protection options are provided by frequency-controlled control units.

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

We often hear from clients that:
- all the pumps are bad (and especially the one that was sold to me - initially a low-quality pump, probably a “left” Chinese one) ...
- we did everything right, according to the instructions, but for some reason the pump burned out ...
- we put a circuit breaker that was supposed to turn everything off ...
- and in the pump, in general, according to the passport, there is a thermal protection (if it is 220V), but it did not work ...
- etc. etc.

Let's try to figure it out.

1. Regarding the sale of low-quality pumps:

No trading company will sell knowingly defective goods, because otherwise you will have to constantly conflict with consumers, repair the goods at your own expense and incur related costs, not to mention the fact that the company's image suffers, etc.
The overall quality level of pumps manufactured in the 21st century is consistently high, with very few exceptions. AMPICA PUMPS does not sell badly proven models, excluding them from its range.
Thanks to many years of experience in selling pumps, we have a stable range of quality, time-tested models from a wide variety of manufacturers.

2. About the manufacturer:

There are no high-quality European submersible pumps on the market at a price below 7 ... 10 thousand rubles.
Anything below that price is made in China. Many European firms only stick stickers and pack Chinese pumps.

At least 70% of European companies manufacture their pumps in China and sell them under their own brand. This doesn't mean they are bad. It is impossible to assemble high-quality products "on the knee". Modern production almost completely automated.
It is extremely difficult to spoil anything during the assembly process. In addition, the time has passed when China did not monitor the quality of products. This is a whole industry and no one will lose a huge sales market for products in Russia.
Naturally, when buying a submersible pump in a large supermarket for 500 ... 900 rubles, you should not count on its trouble-free operation for the rest of your life.
Such goods are sold as a "lure", as related. It is clear to everyone that the buyer will not, because of 500 ... 900 rubles, go to service center to repair the pump to the other end of the city, send it by mail to a service center (sometimes this is a “pleasant” surprise for the buyer) or try to repair the pump yourself.
Because of such "super products" and the credibility of Chinese goods is lost (but, once again, in large stores, only gross sales are important).

Summarize:
- there are no cheap European pumps,
- 2/3 of European pumps are actually made in China and you will pay half the price for the brand name only,
- no need to buy pumps in large supermarkets for 30 kopecks. Nobody canceled the proverb about "cheap cheese".

3. We (clients) did everything right, 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 for the pump. It takes a little time, but it gives an idea of ​​what is good and what is bad for the pump.

4. We had a protection machine ...

The circuit breaker is set to a regular one, which does not track small changes in current. Its power is chosen 2.5 times higher than the power of the pump motor (due to the large starting current). While such a machine “swings”, the pump will already overheat and fail.
In my mind, you need to install not an ordinary machine (which, basically, only saves from short circuits in the network), but an electric motor protection machine. This is a special device that allows you to accurately set the operating current of the motor and monitors its slightest increase due to wedging of the pump shaft.
At the same time, the motor protection circuit breaker allows exceeding the set value of the motor current at the moment of its start.
Usually we offer ABB series motor protection circuit breakers. These motor protection circuit breakers are more expensive than conventional circuit breakers, but they can reliably protect the pump motor from overheating.

Conclusion:
- to protect the motor, the installation of a MOTOR PROTECTOR is required, and not a conventional mains circuit breaker, no need to save on this,
- you should read the instructions, especially the places that are highlighted - it's just about all this is written there.

5. About thermal protection:

Thermal protection is built into the winding and is a kind of relay that, when externally heated, turns off the power to the electric motor.
It should be understood that every time the winding overheats, its insulation melts, that is, irreversible changes occur. After some time (with the next overheating), the insulation will definitely melt completely in some place and short circuit windings, which will damage the motor.
That is, thermal protection is not a panacea for all ills, but only emergency protection, which can save the electric motor several times and nothing more.

6. Work without water.

electric motor submersible pump cooled by the pumped liquid. There are two types of submersible pumps: jacketed and unjacketed.
Jacketed pumps may not be fully immersed in the liquid, as the water will pass through the casing surrounding the pump and cool the motor.
Pumps without a cooling jacket must always be completely submerged in the pumped medium.

From here, 2 main errors arise when installing the pump, which lead to overheating and failure of the electric motor:
- operation of the pump in water with a temperature higher than indicated in the passport for the pump (in the usual version up to +35 ... 40 ° C, and up to + 60 ° C in the heat-resistant version).
This is often the fault of utility workers in the event of accidents in the hot water supply system.
In the event of a pipe rupture hot water pumping it out of the wells is required for repairs. Outdoor pump does not work, because just doesn't absorb hot water due to the fact that it boils in the suction pipe and you have to use a submersible pump, which “dies” from overheating after a few minutes.
There are solutions to this problem, but we won't cover them here.

Operation of a partially submerged pump or a pump without water. In both cases, the motor overheats and fails. A normal automatic protection machine will not track this.

Figure 1. Example of overheating of a pump motor that was not completely submerged in water

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

A common mistake: installing a small capacity in a large area tank.
In this case, the pumping water level decreases very slowly and the pump may long time remain completely immersed in the liquid.
For example, such a mistake was made by our client when installing a pump in a repair dock, where it was planned to pump out water after a vessel was installed in it.

7. The operation of the pump is outside the operating range of flow and pressure.

Let's take a look at specific example: drainage pump GNOM 40/25T .
The pump stood in the pit and supplied water to a height of 7 meters through a 100 mm hose. Next came the pouring of water on the ground.

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

When operating a pump with a head of 7 meters, the pump operates in a flow range that significantly exceeds the operating range (the lower the head, the greater the flow in any centrifugal pump). In this case, the operating current in the pump windings increases greatly, which leads to overheating of the electric motor.
When operating outside the recommended pressure range, install a valve at the pump outlet and set such a supply that the operating current in the motor windings corresponds to that specified in the passport (in this case 12.5A) + install an electric motor protection circuit breaker.
Otherwise, the pump will be overloaded and the motor may be damaged.

When the pump is operating with a pressure of 7-10 meters, the most optimal use of the pump GNOM 53-10T. In this case, no feed adjustment is required.

As can be seen from the above example, it is not necessary to take a pump with a “margin” in terms of pressure, because this can lead to its failure (although it seems that since the pump supplies 25 meters, then there should be no problems when supplying 7 meters).

8. Pump operation on a closed valve / operation through a narrow pipe

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

To prevent fluid overflow, in this case, be sure to install check valve.
If the pump pressure is selected incorrectly (less than in the pressure pipe), then when the pump is turned on, it will work constantly on a closed line, which will lead to its overheating and failure.

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

Some people manage to use a fecal pump that can pump particles up to 50 mm with a 32 ... 38 mm pipe and then they are surprised that for some reason the pipe got clogged and the pump failed.
If you REALLY want to save on pipes, then you can put a fecal pump with a chopper.
In this case, the pipe will not be clogged with large particles (but the pipe diameter is still pre-calculated so that the pump does not work with overload).

The diameter of the pipe depends on the performance of the pump and its length.
Below is a table by which this can be determined:

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

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

10. Work with highly abrasive liquids; a lot of large solid particles.

When pumping liquids with a large amount of abrasive, the shaft seal wears out quickly, which leads to liquid entering the motor housing and causing it to fail.

Often, reading in the instructions that the pump can pump liquids with particles up to 35 ... 50 mm (most household fecal pumps), consumers think that such particles can be stones, nails, rebar, pieces of cement, etc. and in large quantities. In fact, this is not at all the case. If such particles are constantly introduced, this will lead to the destruction of the impeller and seal. Such pumps can pass large particles, but mostly soft ones.
Quite often, construction organizations digging pits save on industrial equipment and buy household pumps for pumping water (why, it will be clear below).
It always ends the same way: they bring pumps that are completely clogged with sand and stones, pumps with broken impellers and casings.
And, as always, we hear the same thing: the pumps are bad, burned out right away, etc.

And now, for reference: for pumping water from the pits, special slurry pumps are required. They are made of special wear-resistant steel and have high-power electric motors.
Prices for such pumps start from 120,000 rubles (for those who are interested, you can see it on our website in the "Sand and Slurry Pumps" section).
And they buy pumps for the same purposes (especially economical builders), for 10-20 thousand rubles.

Figure 2. An example of impeller jamming, due to the ingress of abrasive particles in excess of the allowable value.

11. Frequent on / off pump motor.

Any electric motor, when turned on, consumes current many times greater 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, here is a table:

A common mistake when 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 failure of the pump.
Or the pump is lowered into a narrow well, in which a high-power pump is installed. If a lot of water flows into this well, for example, during a prolonged downpour, then the productive pump quickly pumps out water, turns off, then the water quickly fills a narrow well, the pump turns on, etc. In this case, the permissible frequency of switching on the electric motor may also be exceeded, which will lead to its failure.

It happens that the pump stands in a narrow well and pumps water through a long pipe up the slope. If a check valve is not installed 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, due to the slope, will flow back into the well and fill it, which will turn on the pump. This process can be repeated until the pump burns out.
And it is natural that we will hear the familiar phrase: "the pump is bad."

This malfunction is quite well detected when inspecting the pump - for 220V pumps, the starting winding burns out.

12. Pump operation at reduced voltage; voltage surges.

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

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

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

This is one of the most common ways to "kill" a pump.
When pulled by the cable, there is a violation of the tightness of the lead-in connection of the cable into the motor housing. This leads to water getting inside the motor and its failure.
It also happens that the tightness of the cable is broken (for example, when carrying the pump, it was dropped on the power cable).
Outwardly, this does not manifest itself in any way, but, over time, water enters the electric motor through the cable and disables it.

Figure 3. An example of damage to the power cable and burnout of the winding due to water ingress into the electric motor

14. Use of low-quality start-up and control equipment.

We had one client who “killed” 2 pumps with an interval of one day. When troubleshooting, it was revealed that the electric motor worked on 2 phases instead of three (2 windings of the electric motor burned out).
When they brought the first pump. we highly recommended checking the pump starter. But, as usual, it was said that we ourselves know everything, and so on. etc., and you have “bad pumps”.
After the second pump was brought with the same malfunction, our customers had the sense to replace the starter (price - 500 rubles). After that the problem disappeared. This is how, because of the unwillingness to listen to the advice of professionals, you can save 500 rubles on a starter and pay 30,000 rubles for pump repairs.

15. Connecting the pump by electricians who do not understand what is happening at all.

Now there are many incompetent "workers" who do not understand anything in electrical engineering, but, nevertheless, take on the connection of any equipment. Savings can come out not only in the loss of money, but also in injuries and fire.
Recently, one such person called and was unhappy that his 3-phase pump did 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 wrong and called us on his own.
Before the "murder" of his pump, there was very little left ...

16. Work in aggressive environments.

Many people think that if the pump is made of stainless steel, then you can put it in any container and pump any chemistry with it. Usually, this conviction ends after a few minutes of pump operation (the last minutes of its life).
There is no doubt that such pumps exist, but they only cost from 150,000 rubles and more.
There are many more parts in the pump that must withstand contact with aggressive media. Conventional pumps are not designed for this purpose.

We would like to summarize all of the above:

1. All the causes of pump failure given in this article were real.
2. To design the operation of the pump, it is better to consult with specialists and answer ALL the questions they ask, no matter how “stupid” they may seem to you.
3. It is MANDATORY to install a motor protector.
4. If there is a power surge at the installation site, install a voltage stabilizer.
5. The pump must only be used for its intended purpose.
6. Where increased reliability is required, pumps should be equipped with control and protection cabinets.
Organizations that managed to convince pumps to be equipped with control cabinets, with all possible protections, were convinced that not all pumps are “bad”, but only those that are operated by people who do not monitor the equipment and who do not care what and how happens to it.
Automation monitors various critical situations and has protection from the "fool".

Hope this helps someone right choice pump, and someone to survive the failure of his "faithful assistant" and not shift all the blame on the sellers and the manufacturer.

Today, pumps are used everywhere: in everyday life - for pumping water from a well in order to supply water to a house or water a garden, in construction tasks - to supply cement mortar to an object under construction, in industry - for pumping various liquids, including the most aggressive and toxic. There are many examples of the use of pumps - the fact remains: pumping equipment has become a dense part of modern human life.

On the this moment created great amount various types pumps. Some of the most powerful and efficient are devices that require the connection of an independent (not included in the design of the pump itself) electric motor for their operation. When the question arises about the installation of such systems or their repair, very often there are difficulties with the alignment of the motor rotor and pump shaft.

Why is it so important and how to do it?

What is centering for?

Centering is a process designed to ensure the coincidence of the centers (coaxiality) of any objects (in our case, the pump and motor shafts). If they are not centered with the pump, then the risk of breakdowns in their connecting mechanisms (for example, couplings or belts) increases several times.

In the event of a misalignment in the case of a belt drive, the belt may constantly jump off or be subjected to excessive loads, which will undoubtedly lead to its rapid wear. If, for example, an electric motor well pump is connected using coupling halves, then in this case, if the alignment is disturbed, a strong load will occur on the bearing, which will also cause their rapid failure.

From this we can conclude: alignment is simply necessary for proper and continuous operation. pumping equipment, in which the motor and the pump itself are located on the same shaft.

Alignment of pump and motor shafts

There are several ways to align the pump and motor shafts. Most modern way— use of laser equipment. Such devices make it possible to ensure accurate alignment of the shafts of the motor and pump (or any other equipment) with much less labor. However, due to the high cost of laser devices, lasers are still successfully used. traditional ways centering. Let's look at one alignment method that uses plain wire.

For example, it is necessary to align the coupling halves of the pump and the electric motor. The whole process can be described as follows.

• First you need to determine what and under what to customize. That is, we find the so-called dictating aggregate. If alignment is to be performed on the motor side, then the pump coupling half remains intact (and vice versa).
• Next, two wires of 15 centimeters are fixed on both shafts so that their position is exactly perpendicular to the axis (see image at the very bottom).
• Then the wires are L-shaped bent towards each other in such a way that a small gap of 2-3 mm remains between their ends.
• Now you need to rotate the shaft and make sure that the location of the wires relative to each other does not change.
• If this happens and the distance between the ends of the wire increases or decreases (horizontally or vertically), it is necessary to put shims inside the couplings. Repeat until centering is established.

Centrifugal pumps with an electric motor, unlike conventional designs, are devices consisting of two main components: a centrifugal vane pump and an electric motor. Like all centrifugal pumps, they convert mechanical energy coming from the engine into energy to create a fluid flow, which ensures its movement and pressure in the system.
How to install electric centrifugal pump in the system with your own hands, it is proposed to learn from the article.

How does a centrifugal pump with an electric motor work?

The diagram below shows the arrangement of the internal part and its connection to the electric motor.
In the body, pos. 1, which has the appearance of a snail, concluded Working wheel, blades are located on it. These elements are located on the motor shaft. The suction and pressure pipelines are connected to the discharge and intake openings.
The water that fills the pump, under the action of centrifugal force arising from the rotation of the impeller by its blades, is thrown into the pressure pipeline from the casing. When the impeller turns, a vacuum is created in the suction pipe of the device, due to this, water continuously flows into the suction pipeline.

Tip: Centrifugal pumps can only work when the impeller, and hence the suction pipe, is filled with water. Therefore, in order to keep the water inside the pump if it is stopped, it is necessary to install a receiving device having a check valve at the end of the suction pipe.

If the electric centrifugal pump is put into operation for the first time after completion installation work or repair, it is necessary to first pour water into its body. In this case, you need to ensure that there is no formation of air congestion.
The main performance indicators of pumps are:

• Performance.
• Head.

When choosing centrifugal pumps with an electric motor, you need to pay attention that its performance must correspond to the hourly flow rate of fluid in the system, and the pressure must be sufficient to raise water to the desired height, and be able to overcome the resistance of pipelines and fittings.

Why vibrations occur in a centrifugal pump

Often during the operation of centrifugal pumping units, the problem of vibration arises when electric motors are taken as the drive. There are several ways to correctly and quickly establish this cause.

Tip: Increased vibration greatly reduces the reliability of the equipment. In this case, the pump and motor bearing assemblies may fail, in addition, the electric motor may have a bend or even a break in the shaft, a crack may appear in the end cap or in the stator frame.
From the vibration pump unit the support frame and foundation may be damaged. All this requires the timely elimination of vibrations of the unit.

Vibrations are possible if:

• The instruction manual for the pump has been violated.
• Incorrect alignment of pump and motor.
• Poor quality of manufacture of the coupling, wear of its elements:

1. fingers;
2. lack of coaxiality of the holes for the fingers;
3. misalignment of coupling halves.

• Imbalance of the wheel or rotor, drive pump. Such a defect is especially common in pumps with a high speed or in pumps where the balance is bad.
• Motor rotor imbalance.
• Defective bearings installed in pump or motor.
• Failure to comply with the manufacturing technology of the foundation and base for the unit.
• Got a bent shaft.
• The fixation of individual elements of the pump and the electric motor has loosened: end caps, bearings.

Each instruction manual centrifugal pump indicates a trial run of the electric motor, which must be disconnected from the pump in order to determine the direction of rotation. Here it is necessary to pay attention: is there any vibration of the electric motor during idling.

Tip: If at the time of starting the motor and on Idling works without vibration, then the reasons for this process should be sought: in the wrong centering; in worn fingers or the coupling halves themselves; the presence of imbalance in the connected pump.

So:

• If vibration exists at idle, the cause is a malfunction of the engine itself. In this case, you should check whether the vibration remains immediately after disconnecting the unit from the mains.
• If the vibration immediately disappears after the voltage is turned off, this indicates that there is an uneven gap between the rotor and the stator.
• At start-up, strong vibration at idle may indicate an uneven gap, a break in the rotor winding of the rod.
• If, when the motor is disconnected from the pump, after disconnecting from the network, the vibration does not disappear immediately, but gradually decreases as the speed decreases, then the reason lies in the imbalance of the rotor.
• Vibration caused by wear or defective motor bearings is easily detected. A defective bearing starts to make a lot of noise and get warm.

In the absence of vibration of the electric motor at idle, it is necessary:

• Check if there is an alignment of the pump with the electric motor and the condition of the coupling.
• The compliance of the pump operation mode with the passport characteristics is checked.

Most often in this case, there are two causes of vibration:

• The pump is operated outside working area indicated in the passport. To check the characteristics, a pressure gauge is used, and they measure the readings at the outlet of the pressure from the pump, and, if necessary, adjust the valve on the pressure pipeline.
• The pump is operated in cavitation mode: the reasons in this case may be: the valve is not fully open; blockage of the suction pipe. The check is carried out by measuring the readings of the vacuum gauge on the suction pipeline, and then the obtained values ​​\u200b\u200bare compared with the passport data.

How to ensure the alignment of the pump unit

Tip: The reliability and durability of the operation of the pumping unit depends on the alignment of the pump shaft and the electric motor: their axes in space must be located on the same straight line.

Even with strict adherence to the manufacturing and assembly technology of all parts and assemblies of the unit, alignment is not always maintained during aggregation. Therefore, it is necessary to center the pump and motor shafts.
This operation is performed on a common plate, by adjusting their position with the help of spacers. The manufacturer performs this work before sending the packaged pumps to the customer.
However, alignment can be broken:

• When transporting.
• When deformation of the foundation slab, made of small thickness.
• from aging metal.
• With uneven fit of the unit plate to the foundation.

On fig. 1 shows a diagram of the deviation from the alignment of the shafts.

• Offset in the horizontal plane. The axes remain parallel.
• Offset in the vertical plane. The axes are crossed.

In both cases, when certain values ​​​​are exceeded, the unit does not work normally:

• Noise appears.
• Vibration occurs.
• The power consumption increases.
• Bearings overheat.
• The clutch is hot.

Parts of the electric motor and pump with such deviations wear out much faster than usual. The speed and mass of rotating parts affect the amount of permissible deviations from the alignment of the shafts. The higher the price of the unit, the more stringent the requirements for alignment.
Shaft alignment is shown in the photo.

Alignment of the pump and motor shafts must be carried out in compliance with the following basic provisions:

• In units with a gearbox, the main element is the gearbox. It is installed, verified the correct installation and fixed with pins.
• The electric motor, pump and hydraulic coupling are centered on the gearbox.
• In devices with a fluid coupling, the pump and the electric motor are centered on the fluid coupling, before that it is pre-aligned, then fixed and fixed.
• In units where there is no gearbox, centering is carried out according to the pump, previously verified and fixed.
• The alignment of the unit without a common plate is carried out in two stages:

1. before: before pouring foundation bolts;
2. finally: after fixing the pump to the foundation.

• Center a unit that has a common foundation slab, it is necessary to carry out after its alignment, gravy and tightening of the bolts fixing the foundation.
• The shafts of the pump unit are finally centered after the pipelines are connected to it.

How the pump and motor shafts are centered is well shown in the video in this article.

Hydraulic part of centrifugal pumps.

Pedrollo pumps of the FG series: masters of high power

Centrifugal pumps Pedrollo FG series are real champions. Their flow reaches 6000 l/min! Thanks to this performance, this model has found application in all areas of life - from irrigation suburban areas and pressurization to fire protection installations and circulation systems.

How are they arranged?

Frame Pedrollo FG made of cast iron with anti-corrosion coating. They do not have an engine and operate on the principle of centrifugal force. Their main working part» - an impeller fixed on an open working shaft. It carries out the movement of the liquid entering through the suction grate from the center to the periphery. The impeller blades give the flow acceleration, additional energy and pressure at the outlet. This significantly improves the performance of the pumps. Pedrollo FG series.

9 reasons to buy Pedrollo FG pumps

1. This model consumes little energy, but its power is enough for Agriculture, and for industry, and for security systems.
2. Pedrollo FG do not produce noise.
3. Pedrollo centrifugal pumps of the FG series are used for non-aggressive liquids, including clean water which can be used for culinary purposes.
4. The small dimensions of the pump make it possible to install it even in a dark and uncomfortable space.
5. Pedrollo's FG pumps are among the company's most heat-resistant pumps, withstanding temperatures up to +90°C.
6. All products of the manufacturer are distinguished by their amazing resistance to aggressive environments. It does not rust, does not oxidize, does not collapse from chemical reactions and not afraid mechanical impact. The only "but" - most of the pumps are afraid atmospheric effect, and the FG series is no exception.
7. Even a person who rarely deals with equipment will cope with the control of the pump.
8. Buy pumps Pedrollo FG series maybe even a man of modest means. Agree, it's a shame to deny yourself useful things only because of the financial black line. The creators of the model took this into account and offered extremely affordable prices.
9. Today, more and more customers are seeking to purchase this pump. No wonder - with such high efficiency and ease of use, it will help you out in almost all situations. By all means!

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