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Modern household and industrial pumps work 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 work.
Recently, however, frequency converters have been used for these purposes.
Device and purpose
Frequency converter for the pump performs very useful feature. The fact is that modern pumps remain devices that cannot be properly controlled initially. Of course, you can install a relay on it, but these are only half measures.
With such equipment, the pump motor will always work to the fullest. At the maximum supply of electricity, it works even too powerfully. But the problem here is that it consumes quite a lot of energy.
Moreover, the resulting overpressure in pipes will not lead to anything good. The result is a situation where, due to their design features pumps are inefficient.
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.
Solving the problem is very easy. It is only necessary to install a frequency converter on the pumping equipment. It performs the functions of a stabilizer, automation and regulator of the pump.
Very often, manufacturers of pumping stations integrate converters into the pump circuit even at the assembly stage. A striking example is Grundfos frequency-controlled pumps, which are sold out in stores with increased intensity.
This device looks like a box with electronic stuffing and a small screen. Inside the converter are inverters for voltage equalization, several automation boards and special sensors for measurements.
In expensive models, a microprocessor is built in. 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 with the help of 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. The converter then evaluates the required power of the pump and supplies it with exactly the amount of electricity needed to complete the tasks.
Converters can also provide smooth start engines, their emergency stop, etc. It is very difficult to describe the list of all functions, as developers are constantly improving their products.
The converter can be adjusted with just a few simple commands. Commands are entered using buttons and a screen. The more expensive the device, the more commands it can recognize. Quality converters have dozens of possible modes of operation, speeds and programs.
It is obvious that there are a lot of advantages for converters. It is proved that they pay off already in the first year of operation. There are also disadvantages of such equipment, but they are insignificant.
Advantages of frequency converters:
- Input voltage equalization;
- Pump power adjustment;
- The possibility of saving electricity;
- Increasing the service life of the pump motor;
- Performing the functions of automation of pumping stations;
- The presence of a converter can save you from having to buy a hydraulic accumulator;
- Reducing the noise from the pump.
Cons of frequency converters:
- Quite high price of equipment;
- It is advisable to trust the configuration and connection of the converter to professionals.
About models
Modern manufacturers quickly got their bearings and began to produce converters in large quantities. Pump manufacturers are also not left out. Grundfos frequency-controlled pumps have already been mentioned above, but this practice is also popular with other popular companies.
- Grundfos Cue- This is a frequency converter from a well-known pump manufacturer. They specifically designed the converters to work best with their products. The device is able to finely regulate the operation of the pump, perform the functions of automation and fuse. Cue systems are very diverse and have many variations. You will have to pay a significant amount for the converter. Grundfos Cue systems cost $400-$500. Here, the power of the equipment has a serious effect. The larger it is, the more expensive the converter itself.
- Converter Erman E-9 is a budget solution. The device is able to compensate for torque, smoothly start the pump motor and has up to 24 equipment control modes. Converter power should be selected separately. The body of the device is protected from dust and dirt, which allows it to be used in different situations. The Erman E-9 converter can be bought in stores for $100-150.
- Hyundai N 50 is a single-phase frequency converter domestic use. Its power is at the level of 0.7-2.5 kW. The converter has small dimensions 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- Another popular and versatile model. It can be noted due to the presence of a high-quality drive with vector control. The drive includes the functions of suppressing engine noise, auto-pickup of the rotation of the electric motor, protection of the system from overloads and overheating, as well as the possibility of a soft start. Well, the price of a device called PowerFlex 40 is 350-450 dollars.
The cost of a pump with a built-in converter will be even higher. For example, Wilo pumps with frequency control Stratos 40 sell for 1000-1100 dollars.
Pumps used in systems autonomous water supply and heating, are productive, but at the same time quite costly equipment in terms of operation due to the high level of energy consumption. You can reduce costs and significantly extend the life of the pump by equipping it with a frequency converter, which we will discuss in this article.
You will find out why you need and what functions a frequency converter performs. The principle of operation of such devices, their varieties, specifications and recommendations are given for the choice of converters for borehole and circulation pumps.
1 Why do you need a frequency converter?
Almost all modern pumps sold in the budget and middle price categories are designed according to the throttling principle. The electric motor of such units always operates at maximum power, and the change in the flow rate / pressure of the fluid supply is carried out by adjusting the 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 water hammer, since immediately after turning on the pump begins to pump water through the pipes at maximum power. Another problem is the high energy consumption and rapid wear of the system components - both the pump and the shut-off valves with the pipeline. Yes, and there can be no talk of fine-tuning such a water supply system at home from a well.
The above disadvantages are unusual 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, pumping equipment is always calculated according to the power limit parameter, however, in maximum load mode, the pump operates only during periods of peak water consumption, which is extremely rare. In all other cases, the increased power 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 circulation and borehole pumps.
1.1 Device and operation algorithm
A frequency converter for water supply pumps is an electrical device that converts the direct voltage of the mains into an alternating one at a predetermined amplitude and frequency. Almost all modern converters are made according to the double current change scheme. 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 keys. A corresponding element of the stator winding of the electric motor is connected to each of the keys. Foreign converters use IGBT class transistors, while Russian converters use their domestic counterparts.
The control system is represented by a microprocessor, which simultaneously performs the functions of protection (turns off the pump in case of strong current fluctuations in the mains) and control. In borehole water pumps, the control element of the converter is connected to a pressure switch, which allows the operation of pumping station in fully automatic mode.
The operation algorithm of the frequency converter is quite simple. When the pressure switch determines that the pressure level in the hydraulic tank has fallen 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 affecting the system. Modern converters allow the user to independently set the acceleration time of the electric motor within 5-30 seconds.
During the run-up process, the signal transmitter continuously reports 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 point connected to the pumping station begins to consume more water, the converter will increase the supply pressure by increasing the pump capacity, and vice versa.
1.2 Operation of the pump in tandem 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 controller yourself. As a rule, pump manufacturers in the technical data sheet indicate which particular converter is suitable for this equipment model.
- Power - the voltage converter is always selected based on the power of the electric drive to which it is connected.
- Input voltage - indicates the current strength at which the converter remains operational. Here it is necessary to choose with an eye to the fluctuations that may be in your power supply (low voltage leads to the device stopping, at high voltage it can simply fail). Also consider the type of pump motor - three, two or single phase.
- Adjustment frequency range - for borehole pumps, the optimal range will be 200-600 Hz (depending on the initial power of the pump), for circulation pumps 200-350 Hz.
- The number of strokes and control outputs - the more of them, the more commands and, as a result, the operating modes of the converter, you can configure. Automation allows you to set the speed at start-up, several modes of maximum speed, acceleration rates, etc.
- Control method - for a borehole pumping station, it will be most convenient to use remote control, which can be located inside the house, while a converter with a remote control is perfect for circulation pumps.
If you have filtered out all the devices on the market and are faced with the fact that there is simply no equipment suitable for its characteristics, you need to narrow down the selection criteria to a key factor - the current consumed by the motor, according to which the rated power of the converter is selected.
Also choosing a frequency control unit, especially from domestic or Chinese manufacturers Please note the warranty period. By its duration, one can indirectly judge the reliability of the technique.
A few words about manufacturers. The leading company in this area is Grundfoss (Denmark), which supplies the market with over 15 different models of converters. So, for pumps with a three-phase electric motor, the Micro Drive FC101 model is suitable, for single-phase pumps (operating from a standard 220V mains) - FC51.
More affordable in terms of price is equipment from Rockwell Automation (Germany). The company offers a line of PowerFlex 4 and 40 converters for low-power circulation pumps and a PowerFlex 400 series for borehole pumping stations (3 pumps connected in parallel 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 configuration of such a device should be carried out exclusively by specialists.
The basic element that ensures the functionality of the pump is the electric motor. Previously, the adjustment of the workflow occurred due to automation, now this task is solved by a frequency converter for pumps.
Functional purpose of the frequency converter in the design of the pump
The inverter (frequency converter) regulates the operation of the pump much better than the relay. It works at the same time as a stabilizer, automation and workflow regulator. Thanks to him, 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 excess pressure in the pipes is prevented.
- The problem with power surges is solved, which also definitely increases the life of the pump.
Mostly already in the process of assembling the pumping station is implanted. These devices include models of the very famous Grundfos pump.
Visually, it is a box equipped with electronics (several boards, a sensor that takes measurements, 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 converters used can be of single-phase or three-phase type.
According to the principle of operation, the frequency converter is quite simple. A wave of electric current is applied to the boards of the device. 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. Next, the frequency converter evaluates them, determining the level of power that must be applied, and, in accordance with this, supplying the amount of electricity necessary to continue working.
As a result, the frequency converter can adjust the smooth start of motors, the water pressure level and stop operation in a critical situation. The list of all the "duties" assigned to the chastotnik 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, focusing on the data displayed on the screen. More expensive devices are able to recognize more commands. The highest quality models are designed for several dozen operating modes with a change in speed and program.
The cost of installation and purchase of the converter is fully compensated within one year of operation.
List of positive functions of the frequency converter:
- The ability to equalize the input voltage.
- Ensuring pump power control.
- Creation of conditions allowing to save the electric power.
- Increase 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 substitute for automation.
Negative points:
- The high cost of the device.
- Configuration and connection is usually only available to specialists.
The frequency converter works in the design of the pump as follows: with a significant drop in the pressure level in the hydraulic tank (determined using a relay), the frequency converter receives the appropriate signal and gives the command to start the electric motor. At the same time, everything is carried out “without sudden movements”, the power increases gradually, providing insurance against hydraulic overload. Currently, converter models provide regulation of acceleration time from 5 to 30 seconds.
During acceleration, the converter constantly receives information about the pressure level in the pipeline. As soon as this level reaches the desired value, acceleration stops, the engine continues to operate at the reached frequency.
How to choose and install equipment?
The standard equipment of the pumping station consists of:
- Submersible or surface pump;
- pressure gauge;
- Hose equipped with stainless steel coating;
- Hydraulic accumulator;
- Water pressure switch.
TO additional equipment include:
- Uninterruptible power supplies;
- Sensor;
- blocks;
- Control relays etc.
If the design of existing pumping equipment is not equipped with a frequency converter, then it can be implemented self-installation. Usually, in the documentation attached to the pump model, there are instructions regarding which converter a given type of pump can interact with.
In the absence of such information, it is necessary, based on significant parameters, to select the converter yourself:
- Power level.
It is necessary to match the power of the electric drive and the converter.
- Input voltage value.
An indication of the current at which the converter operates. Here it is necessary to take into account what potential fluctuations in the network can be (a low voltage level provokes a stop, a high voltage level causes a breakdown).
- Pump motor category.
Single phase, two phase or three phase.
- Limits of frequency control range.
For well pump 200 - 600 Hz is required (depending on what the primary power of the pump is), for a circular pump - 200 - 350 Hz.
- Matching the number of control inputs/outputs to operational needs.
The more there are, the more possibilities workflow management.
- Choice suitable way management.
In the case of a borehole pump, remote-type control, which allows control directly from home, and circulation pump works great with 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.
Convert is located as close as possible to the pump, but only inside the heated room. General scheme connecting to the power supply is simple and hassle-free.
Pump transducer models
- Grundfos Cue
Converters manufactured by a company based in Denmark that manufactures pumps. As a result, these frequency converters are designed in maximum accordance with the design of Grundfos pump models. The device is responsible for the fine regulation of the operation of the entire mechanism, the performance of protective and control functions. The 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 frequency converter required for the mechanism of what power. Among the range of models you can find converters for single phase pump(), and for three-phase (Micro Drive FC101).
- Erman E-9
The converters of this company are budget-friendly. Responsible for torque compensation, smooth start, pressure control and have different modes number control up to 24. Compliance with power is selected on an individual basis. There is a protective housing that protects against dust and dirt. 
- Hyundai N 50
Single-phase frequency converter. Can be used in household appliances. The power level is 0.7-2.5 kW. Small-sized, which makes it convenient to install in any devices. It is notable for the fact that it provides fine tuning thanks to several tuning modes and 16 discrete speeds. It costs about twice as much as the previous model.
- PowerFlex 40
Models of this brand are versatile and very popular. Their distinguishing feature— high-quality drive and vector control. The drive, among other things, dampens noise during engine operation, automatically picks up the speed of the electric motor, protects the entire mechanism from overload and overheating, and ensures a smooth start. Cost comparable to Grundfos Cue.
Using the pump in autonomous water supply and heating systems
Pump models in this category are considered very productive, but differ excessively high level power consumption, which, of course, complicates operation. Of course, frequency converters can reduce the amount of energy consumption, the level of pressure and extend the service life.
Most of modern pumps 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 that spoil the design of the pump. To fine-tune such a mechanism, you also need to try hard.
The calculation of data for pumping equipment is always based on the power limit, although the mechanism experiences the maximum load only occasionally at peak water consumption, which happens infrequently. The rest of the time, the implementation of work at the limit of possibilities is completely unjustified. Just at such moments, the frequency converter for the circulation and borehole pumps reduces energy consumption by 30 - 40%.
Among other things, the use of a frequency converter in the pump station providing water delivery helps to prevent the problem of "dry running". It is relevant in cases where there is no water inside the system, and the engine is running further. Due to the “dry run”, the engine may overheat and the mechanism as a whole may break. This once again proves the need to use a converter.
Single-phase frequency converter for a pump within a domestic water supply system
Ergonomics of devices is a very significant 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 cost of the purchase, due to its rare use.
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 made here.
This option is especially important when using hot water. That is, the use of a chastotnik eliminates temperature fluctuations and changes in pressure force.
Single-phase converters are suitable for both submersible and surface pumps.
Single-phase frequency converter for home use
Standard type converters are usually not equipped with a hydraulic connection. An attempt to independently upgrade the device for such needs may be useless, even if a specialist takes up the matter.
Recognizing this problem, frequency converter manufacturers have created a special single-phase frequency converter for a pump that supplies domestic water systems.
One of these converters is equipped with a hydraulic connection and is capable of performing all standard tasks chastotnik.
