Modern domestic and industrial pumps operate by using the power of an electric motor. It is the electric motor that can be considered the real heart of the pump. Initially, only a pressure switch or more complex automation performed the adjustment of its operation.

However, in recent times for these purposes, they began to use frequency converters.

Device and purpose

A frequency converter for the pump performs very useful function... The fact is that modern pumps remain devices that cannot be properly controlled from the outset. Of course, you can install a relay on it, but these are only half measures.

With this type of equipment, the pump motor will always run at full capacity. With the maximum supply of electricity, it works even too powerfully. But the problem here is that it also consumes a lot of energy.

Moreover, the resulting overpressure in pipes will not lead to anything good. The result is a situation where, because of their design features the pumps are not working efficiently.

Do not forget about problems with the supply of electricity, power surges and other unpleasant things. All these points can lead to pump failure or excessive wear and tear.

It is very easy to solve the problem. You just need to install on pump equipment a frequency converter. It performs the functions of a stabilizer, automation and regulator of the pump.

Very often manufacturers pumping stations even at the assembly stage, the converters are integrated into the pump circuit. A prime example is the Grundfos pumps with frequency regulation, which are snapped up in stores with increased intensity.

This device looks like a box with electronic filling and a small screen. Inside the converter there are inverters for voltage equalization, several automation boards and special sensors for measurements.

V expensive models built-in microprocessor. There are also models with batteries, additional equalizers, etc. Converters can be single-phase or three-phase.

The principle of operation of the converter is very simple. Innings electric current first goes to the device boards. There it is leveled using stabilizers and inverters. At the same time, sensors on the transmitter evaluate the pressure level in the system, as well as all other necessary indicators.

The data is fed to the automation unit. Then the transformer evaluates required power pump and supplies it with just as much electricity as is required to complete the tasks.

Also converters can provide smooth start engines, their emergency stop etc. It is very difficult to describe the list of all functions, since the developers are constantly improving their products.

The inverter can be adjusted with just a few simple commands. Commands are entered using buttons and a screen. The more expensive the device is, the more commands it can recognize. High-quality converters have dozens of possible operating modes, speeds and programs.

It is quite obvious that converters have a lot of advantages. It has been proven that they pay off already in the first year of operation. There are also disadvantages of such equipment, but they are insignificant.

Pluses of frequency converters:

• Equalization of the input voltage;
• Regulation of pump power;
• Possibility of energy saving;
• Increased service life of the pump motor;
• Performing the functions of automation of pumping stations;
• The presence of a converter can save you the trouble of buying a hydraulic accumulator;
• Reducing pump noise.

Cons of frequency converters:

• Quite high price of equipment;
• It is advisable to entrust the configuration and connection of the converter to professionals.

About models

Modern manufacturers quickly found their bearings and began to produce converters in large quantities. Pump manufacturers are also involved. It was already mentioned above about Grundfos frequency-controlled pumps, but this practice is popular with other popular companies.

• Grundfos Cue Is a frequency converter from a well-known pump manufacturer. They have specially designed the converters so that they the best way interacted with their products. The device is capable of finely adjusting the pump operation, performing the functions of automation and safety. Cue systems are very varied and have many variations. You will have to pay a significant amount for the converter. Grundfos systems Cue costs $ 400-500. The power of the equipment has a serious impact here. The larger it is, the more expensive the converter itself.
• Erman E-9 converter is an budget decision... The device is able to compensate for the torque, smoothly start the pump motor and has up to 24 modes of equipment control. The inverter power should be selected separately. The body of the device is protected from dust and dirt, which makes it possible to use it in different situations... The Erman E-9 converter can be purchased in stores for $ 100-150.
• Hyundai N 50 Is a single-phase frequency converter for household use. Its power is at the level of 0.7-2.5 kW. The converter is small in size and can be installed almost anywhere. A distinctive feature of this model is the ability to fine-tune it by using several tuning modes and 16 discrete speeds. The Hyundai N 50 model sells for $ 250-300.
• PowerFlex 40 is another popular and versatile model. It can be noted due to the presence of a high-quality vector control drive. The drive includes functions for suppressing engine noise, auto-catching the rotation of the electric motor, protecting the system from overloads and overheating, as well as the possibility of a soft start. Well, the price of a device called the PowerFlex 40 is $ 350-450.

The cost of a pump with a built-in converter will be even higher. For example, Wilo frequency-controlled Stratos 40 pumps sell for $ 1,000-1100.

The basic element that ensures the functionality of the pump is the electric motor. Previously, the adjustment of the working process took place due to automation, now this problem is solved by a frequency converter for pumps.

Functional purpose of the frequency converter in the pump design

An inverter (frequency converter) provides regulation of the pump operation much better than a relay. It works at the same time as a stabilizer, an automation and a workflow regulator. Thanks to it, the high efficiency of the device is ensured:

• The level of electricity supply, if necessary, and the engine speed are reduced, which helps to protect the pump from premature wear.
• The formation of excessive pressure in the pipes is prevented.
• The problem with voltage surges is solved, which also definitely increases the life of the pump.

Mostly already in the process of assembling the pumping station, it is implanted. Such devices include the models of the very famous Grundfos pump.

Visually, it is a box equipped with electronics (several boards, a sensor that measures, and an inverter that equalizes the voltage level) and a small-sized screen.

More expensive samples are equipped with microprocessors. Batteries, additional equalizers, and so on can be built-in.

The used converters can be of single-phase or three-phase type.

The principle of operation of the frequency converter is quite simple. A wave of electric current is applied to the circuit boards of the device. The inverters and stabilizers located there ensure its alignment. At the same time, the sensor reads pressure data and other relevant information.

All information is redirected to the automation unit. Further, the frequency converter evaluates them, determining the power level that needs to be supplied, and, in accordance with this, supplying the amount of electricity necessary to continue working.

As a result, the adjustable frequency drive can adjust the smoothness of starting of electric motors, the level of water pressure and stopping the operation in an emergency. The list of all "duties" assigned to the frequency operator is constantly expanding due to the improvements made by the developers.

The process of controlling the actions of the converter is carried out just by pressing the desired button with orientation to the data displayed on the screen. More expensive devices are able to recognize more teams. The highest quality models are designed for several dozen operating modes with a change in speed and program.

The installation and purchase costs of the converter are fully reimbursed within one year of operation

The list of positive functions of the frequency converter:

• The ability to equalize the input voltage.
• Providing pump power regulation.
• Creation of conditions allowing to save energy.
• Increase in the duration of operation of pumping equipment.
• Providing the ability to work without a hydraulic accumulator.
• Stabilization of intrasystem pressure.
• Reducing the noise level of the pump.

He also works as a deputy of automation.

Negative points:

• High cost of the device.
• Configuration and connection are usually only available to technicians.

The frequency converter works in the pump design as follows: with a significant drop in the pressure level in the hydraulic tank (determined using a relay), the frequency converter receives a corresponding signal and gives a command to start the electric motor. In this case, everything is carried out "without sudden movements", the power increases gradually, providing insurance against hydraulic overload. Currently, the models of converters provide regulation of the acceleration time from 5 to 30 seconds.

While acceleration is in progress, the converter constantly receives information about the pressure level in the pipeline. As soon as this level reaches the desired value, the acceleration stops, the engine continues to operate at the reached frequency.

How do I select and install equipment?

The standard equipment of the pumping station consists of:

• Submersible or surface pump;
• Pressure gauge;
• A hose equipped with a stainless steel coating;
• Hydroaccumulator;
• Water pressure switch.

TO additional equipment include:

• Uninterruptible power supplies;
• Sensor;
• Blocks;
• Control relays etc.

If the design of the existing pumping equipment is not equipped with a frequency converter, then it can be carried out self-installation... Typically, the documentation supplied with the pump model contains instructions as to which converter the pump of this type can communicate with.

In the absence of such information, it is necessary, relying on significant parameters, to select the converter yourself:

1. Power level.

Correspondence is required between the power of the drive and the inverter.

1. Input voltage value.

An indication of the current at which the inverter operates. Here it is necessary to take into account what the potential fluctuations in the network may be (a low voltage level provokes a stop, a high voltage level - a breakdown).

1. Pump motor category.

Single-phase, two-phase or three-phase.

1. Frequency control range boundaries.

For a borehole pump, 200 - 600 Hz is required (depending on what is the primary power of the pump), for a circular pump - 200 - 350 Hz.

1. Matching the number of control I / O to the operational needs.

The more there are, the more possibilities for managing the workflow.

1. Choosing a suitable control method.

In the case of a borehole pump, there is a remote control that allows control directly from home, and the circulation pump works perfectly with a remote control.

It is necessary to determine the reliability of the purchased devices indirectly by the duration of the warranty period. Accordingly, the larger it is, the better the quality.

Where to install the pump converter?

Frequency converters with hydraulic connection are installed directly on the pressure line. Without such a connection, only a water pressure sensor connected to the inverter is attached to the line.

The transform is located as close to the pump as possible, but only inside the heated room. General scheme connecting to power is simple and straightforward.

Models of transducers for the pump

• Grundfos Cue

Converters manufactured by a Danish-based pump manufacturer. As a consequence, these frequency drives are designed in maximum accordance with the design of the pump models from Grundfos. The device is responsible for fine regulation of the entire mechanism, performance of safety and control functions. Transducers of the Cue system are distinguished by a variety of high-quality models (more than 15 types in the range), but their cost is appropriate. In addition, the price directly depends on the power required for the mechanism of the frequency converter. Among the range of models, you can find converters for a single-phase pump (), and for a three-phase (Micro Drive FC101).

• Erman E-9

The converters of this company are distinguished by their budget. They are responsible for torque compensation, smooth start-up, pressure control and have up to 24 different control modes. Power matching is selected individually. There is a protective case that protects against dust and dirt.

• Hyundai N 50

The frequency converter is single-phase. Can be used in household appliances. The power level is 0.7-2.5 kW. Small-sized, which makes it easy to install in any device. It is notable for the fact that it provides fine tuning thanks to several tuning modes and 16 discrete speeds. It costs about double the previous model.

• PowerFlex 40

Models of this brand are versatile and very popular. Their distinctive feature- high-quality drive and vector control. The drive, among other things, dampens noise during engine operation, automatically picks up the speed electric motor, protects the entire mechanism from overload and overheating, provides a smooth start. The cost is comparable to Grundfos Cue.

Using the pump in autonomous water supply and heating systems

Pump models in this category are considered very productive, but they have an excessively high level of energy consumption, which, of course, makes it difficult to operate. Of course, frequency converters can reduce the amount of energy consumption, the pressure level and extend the service life.

Most modern pumps are designed according to the throttling principle. The electric motors of these mechanisms are in operation at the upper power limit, that is, literally for wear. Often, due to the lack of smoothness when turned on, powerful hydraulic shocks are observed, which spoil the design of the pump. To fine-tune such a mechanism, you also need to try pretty hard.

The calculation of data for pumping equipment is always based on the maximum power level, although the mechanism experiences maximum load only occasionally at peak water consumption, which does not happen often. The rest of the time, working to the limit is completely unjustified. Just at such moments, a frequency converter for a circulation and borehole pump reduces energy consumption by 30 - 40%.

Among other things, the use of a frequency converter in the pump station providing water delivery prevents the problem of "dry running". It is relevant in cases where there is no water inside the system, and the engine continues to run. Due to "dry running", the engine may overheat and breakdown of the mechanism as a whole. This proves once again the necessity of using a converter.

Single-phase frequency inverter for a pump in a domestic water supply system

Ergonomics of devices is a very important indicator in the framework of consumer services. Improving this parameter for a water supply system using a low-power single-phase pump model is difficult, since this requires a converter with an input / output voltage level of 1x220V, and it is not easy to find one.

Usually household pumps have no complaints about energy consumption, but this does not compensate for the purchase costs, due to its rare operation.

However, the installation of the converter does not lose its relevance, since it helps to maintain a constant network pressure. In other words, a request for comfortable operation is carried out here.

This option is especially important when using hot water... That is, the use of a frequency converter eliminates temperature jumps and changes in the pressure force.

Single-phase converters are suitable for both submersible and surface pumps.

Single Phase Frequency Converter for Home Use

Converters standard type usually not equipped with a hydraulic connection. An attempt to self-upgrade the device for such needs may turn out to be useless, even if a specialist gets down to business.

Recognizing this problem, manufacturers involved in the production of frequency converters have created a special single-phase frequency converter for a pump that provides domestic water supply systems.

One of these converters is the one equipped with a hydraulic connection and capable of performing all standard frequency converter tasks.

Pumps used in systems autonomous water supply and heating, are productive, but at the same time quite costly in terms of operation equipment due to high level energy consumption. You can reduce costs and significantly extend the life of the pump by equipping it with a frequency converter, which we will talk about in this article.

You will find out why you need it and what functions the frequency converter performs. The principle of operation of such devices, their varieties, specifications and recommendations are given for the selection of transducers for borehole and circulation pumps.

1 Why do you need a frequency converter?

Almost all modern pumps sold in the budget and mid-price category are designed according to the throttling principle. The electric motor of such units always operates at maximum power, and the change in the flow / pressure of the fluid supply is carried out by adjusting shut-off valves, which changes the cross-section of the through-hole.

This principle of operation has a number of significant drawbacks, it provokes the appearance of hydraulic shocks, since immediately after switching on the pump begins to pump water through the pipes at maximum power. Another problem is high energy consumption and rapid wear of system components - both the pump and the valves with the pipeline. And there can be no talk of fine tuning such a water supply system at home from a well.

The above disadvantages are not typical for pumps equipped with a frequency converter. This element allows you to effectively control the pressure created in the water supply or heating pipeline by changing the amount of electricity supplied to the motor.

As you can see in the diagram, the pumping equipment is always calculated according to the parameter of the maximum power, however, in the maximum load mode, the pump operates only during periods of peak water consumption, which is extremely rare. In all other cases, the increased capacity of the equipment is unnecessary. The frequency converter, as statistics show, allows you to save up to 30-40% of electricity during the operation of circulating and borehole pumps.

1.1 Design and algorithm of work

A frequency converter for water supply pumps is an electrical device that converts a DC voltage to an AC voltage at a predetermined amplitude and frequency. Almost all modern converters are made according to the scheme of double current change. This design consists of 3 main parts:

• uncontrolled rectifier;
• pulse inverter;
• control system.

The key design element is a pulse inverter, which in turn consists of 5-8 transistor switches. A corresponding element of the stator winding of the electric motor is connected to each of the keys. In foreign converters, transistors of the IGBT class are used, in Russian - their domestic counterparts.

The control system is represented by a microprocessor, which in parallel performs the functions of protection (turns off the pump in case of strong fluctuations in the current in the mains) and control. In borehole pumps for water, the control element of the transducer is connected to a pressure switch, which allows the pumping station to operate in a fully automatic mode.

The operation algorithm of the frequency converter is quite simple. When the pressure switch detects that the pressure level in the hydraulic tank has dropped below the permissible minimum, a signal is transmitted to the converter and it starts the pump electric motor. The engine accelerates smoothly, which reduces the hydraulic loads acting on the system. Modern converters allow the user to independently set the acceleration time of the electric motor within 5-30 seconds.

During acceleration, the signal transmitter continuously transmits data on the pressure level in the pipeline to the transmitter. After it reaches the required value, the control unit stops acceleration and maintains the set engine speed. If the water consumption point connected to the pumping station begins to consume more water, the converter will increase the supply pressure by increasing the pump performance, and vice versa.

1.2 Pump operation paired with a frequency converter (video)

If the pump you are using does not have a built-in frequency converter, then you can purchase and install such a power regulator yourself. As a rule, pump manufacturers in the technical passport indicate which specific converter is suitable for this equipment model.

1. Power - the voltage converter is always selected based on the power of the drive to which it is connected.
2. Input voltage - indicates the amperage at which the converter remains operational. Here it is necessary to choose with an eye on the fluctuations that may be in your power grid (undervoltage leads to a stoppage of the device, with an increased voltage it can simply fail). Also consider the type of pump motor - three, two or single phase.
3. Adjustment frequency range - for borehole pumps, the optimal range will be 200-600 Hz (depending on the initial pump power), for circulating pumps, 200-350 Hz.
4. The number of control strokes and outputs - the more there are, the more commands and, as a result, the operating modes of the converter you will be able to configure. Automation allows you to set the speed at start-up, several modes of maximum speed, acceleration rates, etc.
5. Control method - for a borehole pumping station, the most convenient will be a remote control, which can be located inside the house, while a converter with a remote control is perfect for circulation pumps.

If you have screened out all the devices on the market and are faced with the fact that there is simply no equipment suitable for the characteristics, you need to narrow the selection criteria to the key factor - the current consumed by the motor, according to which the rated power of the converter is selected.

Also, when choosing a frequency control unit, especially from domestic or Chinese manufacturers, consider the warranty period. By its duration, one can indirectly judge the reliability of the equipment.

A few words about the manufacturers. The leading company in this area is Grundfoss (Denmark), which supplies the market with over 15 different models converters. So, for pumps with a three-phase electric motor, the Micro Drive FC101 model is suitable, for single-phase (operating from a standard 220V power supply) - FC51.

More affordable in terms of price is the equipment of the Rockwell Automation company (Germany). The company offers a line of PowerFlex 4 and 40 converters for low-power circulating pumps and a PowerFlex 400 series for downhole pumping stations (3 parallel-connected pumps can work from one converter at once.

Keep in mind that the price of a good converter can sometimes reach the cost of a pump, so the connection and adjustment of such a device should be carried out exclusively by specialists.