Automation unit for a pump with frequency conversion. The principle of operation and installation rules for a frequency converter for a pump

Most common industrial models of frequency converters can be used to control pumps, but for this they need to be programmed in a special way.

Frequency converters for pumps are adapted devices and show the best results when working with pumping equipment. Frequency converters for pumps are more economical and functional in their field.

Models of devices and analogues

The table below shows short review several pump-optimized models. Detailed information by models can be obtained on the card of the corresponding frequency converter.

Applications for frequency converters for pumps

Pump inverters are optimized for the following applications:

• Ventilation and air conditioning systems (compressors, etc.)
• Housing and communal services, water supply and sanitation systems, heating (hot pumps / cold water, boiler room equipment, sewerage)
• Energy (equipment of thermal power plants, thermal power plants, boiler units)
• Technological lines in the processing industry (sand, slurry pumps)
• Other pumping units (pumping stations for water supply networks or power distribution points)
• Submersible, borehole pumps

Despite the above applications, such devices are also suitable for general industrial applications.

Purpose of frequency converters for pumps

• Optimized control in pumping systems in order to maintain certain parameters at a given level (pressure, temperature, level, flow, water consumption)
• Group control of pumps
• Saving water and electricity at enterprises, saving resources at pumping stations
• Protecting pipelines from water hammer, increasing the service life of fittings
• Full protection of electric motors in pumping installations
• Automation of pumping stations

Advantages

Frequency converters for pumps have the following advantages:

• They usually have more high level protection
• Thanks to their specialization, they realize the most effective management in pumping systems
• In most cases, they are multifunctional devices that can fully automate the pumping station.

Flaws

The disadvantages of devices are influenced by the principles of regulation used in them. Depending on whether it is a scalar or a vector converter, certain disadvantages are inherent in it. (links to pages)

The principle of operation of frequency converters for pumps

The frequency converter for pumps converts the input power voltage into the output voltage that is optimal for the selected operating mode of the pump. In this case, a control loop is formed in the system with feedback on the selected parameter (for example, on the water pressure in the water supply system). The pressure sensor transmits information to the electronic unit of the inverter, and the converter, in turn, changes the output (frequency, voltage) in one direction or another to maintain a constant water pressure in the pipeline.

Examples are shown in the figures:

Pump station for two pumps
(automatic maintenance of pressure, start-up of an additional pump from the network)

Automation of pumping equipment can be considered the most important aspect in the field of technical development of water supply and sanitation systems. This is important not only for stations that provide water to settlements.

A smart pump for a well will also make the operation of an autonomous water supply system comfortable. To do this, it is very important to correctly calculate well pump, and according to the calculations obtained, select a frequency converter for it.

The video in this article will help you do it yourself.

Advantages of automatic water supply

In order to achieve the most gentle operation of the equipment, on pumping stations automate everything - from starting and stopping the units, and ending with the control of water consumption. Devices that help to exercise total control over the system transmit signals to the scoreboard in the control room.

Approximately the same, only on a smaller scale, occurs in the case of home pump automation. Let's look at the advantages that automation gives to the system.

So:

• The most important thing is that the smooth start and stop of the pump motor reduces the likelihood of water hammer to zero, and the careful operation mode helps to extend the life of any equipment. This reduces the costs associated with the operation of the water intake.
• First of all, it is the consumption of electricity. Its price is steadily growing, and everyone feels it: both individuals and enterprises. Frequency regulation of the operation of pump motors makes it possible to reduce the volume of storage tanks, and even completely abandon them.

In such cases, they use a device called: "inverter control unit for a borehole pump" - it is what you see in the photo above. The inverter combines various combinations control devices, which the pump itself is not equipped with, and, among other things, has a built-in frequency converter.

Functionality and selection of the frequency converter

It is clear that the maximum consumption of water occurs only at certain moments, and most time, the pump power is excessive. The frequency converter allows you to configure the system so that during the "rush hour" the pump gives out full power, and at other times it reduces speed.

• From the number of rotations in a certain period of time of the pump wheel, the pressure developed by it depends, and, accordingly, the performance. The essence of using a frequency converter is to make the motor shaft rotate at a given pace. In this case, the frequency of the alternating current received from the mains changes its value.
• Modern converters have the widest range, and are able to convert voltage both above and below the characteristics of the mains supply. The circuit of this device is divided into two parts: a power one, consisting of a group of transistors or thyristors, and a control one, which, in fact, is an electronic key.
• The control part consists of digital microprocessors, and performs all control and protective functions. Since the structure of the power section has characteristic differences, frequency converters are divided into two groups. One of them includes devices with an intermediate DC link.

• The second group does not have this link, and is called "frequency converters with direct connection". Devices without an intermediate link have a higher efficiency, and are able to "curb" the most powerful high-voltage motor. Despite the fact that the price of this option is higher, the system in which it is implemented is much more economical in terms of costs.
• What is the cost savings? The fact is that such converters have a small frequency range, and it cannot be equal to or exceed the characteristics of the supply network. The standard frequency of the current in the network is 50 Hz, and the device converts it to 30 Hz and below, down to zero. Consequently, the consumption of electricity is reduced - here's the savings for you!

Such a limited range does not allow the use of converters of this type in industrial scale. But for household pumps this is just what you need.

Selection of a pump for a well

First of all, it must be borne in mind that the power characteristics of the pump must exceed the calculated consumption. That is, there should always be a reserve of power.

The calculation is based on the following data:

• depth and
• Diameter casing pipe
• , and if it is simpler - the distance from the water mirror in the well to the surface of the earth with the pump running
• Total daily water consumption for a family, keeping animals and watering (calculated based on existing standards)
• Well distance from home
• Height of water supply (taking into account the number of storeys of the building)
• Pressure pipe diameter

The pump pressure for a well, from which water will be supplied directly to the house, is the sum of the length of vertical and horizontal distances, multiplied by the resistance of the pipeline - this coefficient is a constant value, and is equal to 1.15.

• If there is a storage tank in the water supply system, then the pressure of the hydraulic tank is also added to the sum of the distances. Pressure is expressed in atmospheres, and each atmosphere is equal to 10 vertical meters.
• Consider how the calculation will look like specific example. Let's say you have a well with a dynamic level of 35 m. It is located 20 m from two-story house 7 m high. At the same time, a hydraulic accumulator with a capacity of 60 liters and a pressure of 3 atm is installed in the house.

The calculation of the pressure will look like this: H \u003d (35 + 20 + 7 + (3 * 10)) * 1.15 \u003d 105 meters.

If we take into account a small margin, then you can buy a pump with a pressure characteristic of 110-115m. As you can see, the complexity this calculation does not represent. Now let's talk about the criteria for selecting a frequency converter, abbreviated PE.

Transducer selection

Concerning specifications PE, then they must be related to the type and power of the electric motor to which it will be connected. Further, it is necessary to take into account the required control range, as well as the level of tuning accuracy and maintaining the torque on the motor shaft.

• The design features of the inverter, that is, its dimensions, configuration, built-in or remote control, also matter. The vast majority of installed asynchronous motors. To them, the frequency converter is selected according to power, and it is better if this characteristic of the converter is an order of magnitude higher than that of the pump.

• There are converters with vector control that allow you to maintain the rotation speed under variable loads, as well as work without reducing the speed in the zero range. Such converters most accurately control the torque and shaft speed. This is especially important when there are two pumps in the network.
• In general, frequency converters have their own classification. Like any other electrical equipment, they can be single-phase and three-phase. The version of the inverters can be household, for a 220V network. There are also industrial converters with power up to 500V, and high-voltage converters up to 6000V.
• The degree of IP protection is also different. By type of control, PE are divided into vector and scalar. All leading manufacturers of pumping equipment offer consumers inverter units. Typically, manufacturers link converter models to specific pump modifications and give recommendations for their use.

The buyer does not even need to think much about the choice: the sales consultant will indicate to you the converter model suitable for this pump, and explain to you what are the features of its use.

The use of frequency converters to control pumps is now a necessity, not a luxury. Thanks to frequency regulation, it is possible to reduce electricity consumption at times of reduced water consumption, as well as to get rid of excess pressure in the network, which is often the cause of accidents. Thanks to the use of frequency converters, it became possible to maintain a constant water pressure at the consumer.

How does frequency conversion work for pumps?

Let's take a pump that is powered by a two-pole motor with a shaft speed of 2800 rpm, while at the output of the pump we get a nominal head and performance. Now, with the help of a frequency converter, we will lower the frequency, which will entail a decrease in the engine speed, which means that the pump performance will change. With the help of a sensor, information about the pressure in the system will enter the frequency converter unit, and therefore, based on the data from the sensor, the frequency supplied to the electric motor will change.

What frequency converters can be used for pumping units?

There are various manufacturers offering specialized frequency converters for pumps, including Vacon 100 Flow (a novelty from the Finnish manufacturer Vacon), INNOVERT VENT (China), and other models. They are compact, have a user-friendly interface and can be implemented in various degrees of protection (IP 21, IP 54, IP65). The highest degree of protection is IP 65, which is waterproof and dustproof, but at the same time has a higher price.
The power range in which frequency converters are presented is quite wide: from 0.18 to 315 kW and more, when powered by 220 and 380V from a 50-60Hz network.

The use of frequency converters for borehole pumps

In order to select a frequency converter for a borehole pump, it is necessary to take into account the depth of the well. For example, when an artesian well is more than 100 m deep, it is necessary to use chokes that can increase the wear resistance of the cable insulation and reduce other undesirable effects.

ANS with frequency converter

In the section "Pumps" we will consider automatic pumping stations with a frequency converter. These stations are intended for feeding in systems autonomous water supply pure water, not containing chemically aggressive substances, mechanical and long-fiber inclusions with a constant predetermined pressure. The frequency converter (inverter), smoothly changing the engine speed, provides a constant pressure in the water supply system, regardless of the water flow, thereby saving energy, increasing efficiency and implementing the main protective functions (full protection of the engine, protection of the pump from running in the “dry run” mode) ), increasing the service life of an automatic pumping station. Automaticpumping station with frequency converter comprises centrifugal pump driven by an asynchronous motor, frequency converter and . The frequency converter is controlled by a pressure sensor with an analog output, 4-20 mA, which is mounted on the pump discharge pipe.

Key features and design

The main characteristics of pumping stations with frequency converters:

• Temperature environment: from +1ºС to +40ºС;
• Maximum relative humidity: 50% at +40ºС (non-condensing)
• Protection class: IP-54
• Temperature of the pumped liquid: from +1ºС to +40ºС;
• Type of pumped liquid: water that does not contain chemically aggressive substances and solid suspensions;
• Rated motor power: up to 2.2 kW (3 HP);
• Frequency converter input voltage:

IMTP inverter 2.2kW x 1~(100-244)V / for pump 3~(100-244)V (50-60Hz);

ITTP inverter 2.2kW x 3~(200-440)V/ for pump 3~(200-440)V/ (50-60Hz);

• Frequency converter output voltage: depending on the input voltage and motor characteristics;
• Frequency at the output of the frequency converter: 0-55 Hz;
• Nominal electricity at the input of the converter: 11 A for (IMTP), 6.5 A for (ITTP);
• Rated electric current at the output of the converter: 10 A for (IMTP), 6.0 A for (ITTP);

The design of a pumping station with an inverter is shown in (Fig. 1). It consists of a centrifugal pump driven by an asynchronous motor, a frequency converter, an analogue pressure transducer, a hydraulic accumulator (capacity 19, 20 or 24 liters as standard), a pressure gauge, connecting fittings and electrical connections.

1. Pump - This is the main element of an automatic pumping station.
2. Hydraulic accumulator used for the correct operation of the pressure sensor and increase the volume of the stock drinking water, regulation of the number of switching on and off the pump, and also serves as a base for mounting the pump.
3. Frequency converter (inverter) serves for smooth start and stop of an asynchronous motor, controls the pump drive according to a given operation algorithm, and also provides full protection engine. Adjustment of the number of revolutions of the electric motor occurs by changing the frequency of the alternating current and the magnitude of the voltage supplied to the motor. The inverter is mounted directly on the place of the standard terminal box of the pump motor. The inverter is cooled by the air supplied by the motor fan.
4. Pyaternik used for convenience and quick installation pressure sensor, manometer and flexible hose.
5. flexible hose with a corner used to connect pumping equipment to a hydraulic accumulator
6. pressure gauge is used for visual control of the switching on and off pressure of the automatic pumping station.
7. Connecting cables are used to connect the frequency converter to the mains supply and connect the pressure sensor to the inverter.

Installation, electrical connection and adjustment

Before installing the station, it is necessary to choose the right place for installation. It is recommended to mount the station with an inverter in a pit, ground floor or basement on a level, level surface, in a dry, ventilated and weather-protected area. The station can be connected directly to the water supply network or draw water from a tank. It is necessary to make sure that the total pressure in the water supply network and maximum pressure created by the pump does not exceed the value of the maximum working pressure (nominal pressure) of the pump itself and the accumulator. On the suction and pressure pipes immediately before automatic station it is necessary to install shut-off valves and detachable connections, for ease of dismantling and repair.

Suction pipeline:

1. must have the same orifice as the suction port of the pump or, if possible, one size larger.
2. should be as short as possible, without diameter truncations and sharp turns. The longer the suction pipe, the more resistance it creates, and the less depth the pump can raise water to the surface.
3. must be positioned so that it always slopes upwards towards the pump. Avoid air pockets in the suction pipe.
4. must be airtight and prevent fluid leaks or air leaks. All connections must be carefully checked for tightness.
5. must always be installed with a mesh to prevent air in the pump and piping after the pump has stopped. check valve mesh also protects the pump and downstream equipment from large particles such as leaves, twigs and insects.

Pressure pipeline:

The diameter of the pressure pipeline is calculated based on the number of draw-off points and the maximum possible water consumption.

Electrical connection:

These automatic pumping stations with a frequency converter are manufactured and configured, as a rule, on an individual order and under specific tasks. Complete assembly installation and configuration of the station takes place in service center. Of the electrical connections, the consumer only needs to plug the plug into a grounded socket if the frequency converter is monophase IMTP, or supply 380 V with a four-wire cable if the frequency converter is three-phase ITTP. The electrical connections of the ITTP frequency converter are shown in (Fig. 2) power section.

The frequency converter has an input filter due to which possible interference in the power supply is excluded. In addition, the inverter is equipped with a built-in overcurrent fuse, which guarantees absolute protection for a motor with a rated power not exceeding the rated power of the inverter.

The IMTP single-phase frequency converter is installed on asynchronous three-phase motors with a voltage of ~220 V, 50/60 Hz. The windings of such a motor must be connected in a delta pattern if the motor is designed for a voltage of 230V in the delta / 400V in the star.

The ITTP three-phase frequency converter is installed on an asynchronous three-phase motor with a voltage of ~200-440 V, 50/60 Hz. The windings of such a motor must be connected in a "star" if the motor is designed for a voltage of 230V in the "triangle" / 400V in the "star".

(Fig. 3) shows the motor connection diagrams according to the "triangle" and "star" schemes.

The inverter can handle pumps up to 2.2 kW (3HP) and 50 to 60 Hz. The frequency converter is equipped with output current protection; between the inverter and the pump, there is no need to install additional protection devices in order to protect the motor in case of an emergency.

(Fig. 4) shows the connectors for connecting control signals: , or , as well as a connector for connecting frequency converters in a cascade.

The station with the frequency converter must be connected to the network electrical supply in accordance with current safety standards and regulations. The equipment connection point must be equipped with the following components:

• Equipment protection device (RCD) with a rated leakage current of 30 mA
• A circuit breaker with a minimum contact gap of 3 mm.
• grounding

Frequency converter setting:

After assembling an automatic pumping station with a frequency converter in a service center, it is installed on a bench for hydraulic testing and adjustments. It is necessary to fill the suction pipe and the pump itself with liquid and remove all air. To automatically adjust the frequency converter to the pump parameters, it is necessary to disconnect the accumulator, and install a shut-off valve on the outlet pipe behind the pressure sensor. To enter the "ENGINE PARAMETERS" settings, you must first enter the PASSWORD. Then you need to set the rated current of the motor, which is indicated on the rating plate. When starting for the first time, you need to check the correct direction of rotation of the motor by observing the rotation of the fan. The direction of rotation can be changed by changing the value of the parameter: "MOTOR PARAMETERS", rotation from 0 to 1. At the first start, the frequency converter determines the maximum performance of the pump. After testing, you must "SAVE DATA". To save the test data, select YES and confirm with Enter. Then the desired operating pressure "SET PRESSURE" is set using the (+) and (-) buttons.

• Checking engine shutdown with closed feed: After the data obtained at the first start have been saved, it is necessary to open the shut-off valve on the supply, press the Start button and wait for some time necessary for the pressure to stabilize, and then slowly close the shut-off valve and make sure that the engine has stopped (after about 5 - 10 seconds ). The message “MINIMUM FLOW” will appear on the display. This value must be finely adjusted to stop the engine reliably. The absolute value of the engine stop power is shown on the display.
• Checking the functioning of the pump in dry running: To check that the pump has stopped running dry, close the valve on the supply pipe so that the pump runs dry. After approximately one minute (factory setting of the delay time) the pump should stop, signaling “DRY RUN” on the display. If after this time the pump has not stopped, you need to set more high value parameter COS FI (default value 0.55).

On the front panel of the frequency converter there are LEDs, a display and control buttons, the purpose and description of the LED indications of the display and control buttons is shown in (Fig. 5) .

Included with the frequency converter is an instruction manual for using the inverter. This manual describes in great detail the installation and connection of the inverter, commissioning, settings and alarm conditions.

Before putting an automatic pumping station with a frequency converter into operation, it is necessary to check the pressure in the air chamber of the accumulator, which should be approximately 0.2-0.3 bar (atm.) Lower than the pump turn-on pressure (atm.) You can control the pressure level in the accumulator using a conventional automobile pressure gauge . If the pressure is insufficient, it must be raised to the required level using a pump or compressor. If the air pressure is greater than necessary, bleed excess air to the norm.

Operation, maintenance and repair

At correct installation and compliance with the operating conditions automatic pumping stations with frequency converter practically do not require maintenance and repair. For the correct operation of the pressure sensor, approximately once every six months, it is necessary to service the accumulator and check the air pressure in it. How to properly check the pressure and adjust the accumulator, you can see . If the station will not be used for a long time (for example, in winter), it is recommended to disconnect it from the water supply, rinse with clean water, then completely drain the water and install it in a dry, heated room. Before starting the operation of the station, it is necessary to fill the suction pipeline and the pump itself with water. Before starting an automatic pumping station with a frequency converter into operation after long downtime it is necessary to make sure that the motor shaft rotates freely (not jammed) by turning it by the blowing impeller.

And in conclusion, the following can be noted, the initial costs for the purchase of a pumping station with a frequency converter are significant, but they are more than paid off during operation, due to saving electrical energy.

Thank you for your attention.

Many pumps are used in building life support systems. They perform a wide variety of functions. The most famous of them is a circulation pump for heating systems. Apart from circulation pumps in systems for various purposes are used:

• pumping units for increasing pressure, necessary to supply water to the building with insufficient pressure in the city water supply system;
• circulation pump for heating systems;
• pumps for DHW systems providing the supply hot water at any time at any tap;
• pumps for removal and drainage of sewage and dirty water;
• pumps for fountains and aquariums;
• pumps for fire fighting applications;
• pumps for cold water and cooling systems;
• pumping installations using rainwater for toilets, washing machines, cleaning or watering;
• borehole pumps

Today, the pump is the most common, which is used almost everywhere. Open the mixer, water will flow from it, which is pumped by the pump. Each car has several pumps for oil, fuel, water, coolant. A cyclist won't hit the road without pumping up the tires. In the manufacture of an electron lamp, air is pumped out of it. Pumps inflate, pump out, pump out and pump air, water, oil, milk, gasoline and even cement. From plumbing to a rocket, from a fan to a nuclear power plant - this is the range of applications for pumps.

But the pump itself cannot work. To drive it, you need an electric motor and a pressure or vacuum control device for vacuum pumps. The most well-known and common method of regulation in the pumping system is damper regulation, when the engine is running at full speed, and the pressure in the system is regulated using shut-off valves (gate valves, valves, taps, ball valves, etc.). If we draw parallels with driving a car, then the damper control looks something like this: the driver, pressing the gas pedal all the way, controls the speed of the car with the brake pedal.

Manage pumps more rationally and efficiently frequency converters, with which the engine is supplied required amount energy to create and maintain the required level of pressure / vacuum in the system, for example, in a pipeline. At the same time, up to 50% savings in energy consumption are achieved, and if we consider that during the life of the engine, it consumes electricity in an amount that far exceeds its cost, then this indicator turns out to be extremely relevant. For example, during a year of operation for 8 hours a day, an 11 kW engine will consume electricity in the amount of about 85 thousand rubles. Frequency converter with such parameters of work, it will pay off within a year, and in the future it will bring profit to the enterprise.

Let's consider the methods of pressure control in the pumping system described above in more detail.

The top figure shows typical scheme calculation of the required pump power. The pump power for a particular system is always calculated according to the level of maximum consumption, that is, with a certain margin. The blue line shows the pump curve - the supplying part of the water supply system, which reflects the dependence of the discharge pressure on the amount of fluid flow (flow). The red line is the system curve - the consuming part of the water supply, which also displays the interdependence of the flow rate and pressure of the liquid, but in a mirror image. The intersection of these curves is the optimum point when the pump provides the required flow and the required pressure level.

But in fact, the system rarely works in this mode, only at times of peak consumption. The rest of the time, the rated power of the pump is excessive, and then in systems without regulation or with the use of a damper, the following happens: when the flow decreases, the pump creates overpressure, the creation of which consumes additional energy. The figure below clearly shows this.

The use of frequency converters, by reducing the engine speed and, as a result, the supplied power, allows you to change the "pump curve" by adapting it to the "system curve"

Benefits of operating a water supply system with a frequency converter
High efficiency 90%
Low energy costs
constant pressure in the system,
no need for automation
no need for maintenance,
no expansion tank required
no need for maintenance,
no need for taps, couplings and tees for diagnostics and draining expansion tank and automation
implementation in any system MODBAS, IZERNET, PROFIVAS, etc.
control of pressure, switching on, by timer, night-time mode from any panel, computer, the data is always on the screen before your eyes.
Monitoring of current, voltage, malfunctions, breaks, short circuits of the pump motor.

Water supply pump control

As you know, water consumption for economic and domestic needs fluctuates greatly during the day, during weekends and holidays. A lot of people shower, do laundry, do dishes at the same time during certain hours of the day and hardly use water at other times, for example, at night. This creates the conditions for such problems as poor water pressure in the morning and evening hours, significant daily pressure fluctuations in the water supply system and, as a result, accelerated wear of pipes and valves.

Fortunately, today pressure stabilization is not such a big deal. challenging task. Today, the issue of increasing the overall efficiency of managing water supply systems, that is, achieving maximum results with minimal energy consumption and insignificant capital investments in equipment modernization, is already more relevant. Usage frequency converters at pumping stations allows you to brilliantly cope with this task. Statistics show that the frequency converter is able to reduce energy consumption at pumping stations from 30 to 50%, and their payback period is from one to one and a half years.

The figure on the left shows the start of a pump motor using a contactor.

The figure on the right shows the start of a pump with a frequency converter.

This savings is achieved due to the fact that frequency converter able to change the frequency of rotation of the electric motor smoothly over a wide range. In fact, this means that the pump motor will always consume exactly as much energy as is necessary to maintain a stable pressure, regardless of the current consumption of the water supply system at that particular moment. Soft start, stopping and changing the engine speed also helps to avoid hydraulic shocks in pipelines, reducing water losses and increasing the period of trouble-free operation of the pump, pipeline, valves and measuring instruments.

The video shows the principle of operation of a frequency converter in a pumping station

Selection of a frequency converter for pumps

Company Control Systems offers frequency converters for a wide variety of pump control tasks:

• control of single low-power pumps,
• cascade control of a group of pumps with replacement,

We work with many manufacturers of frequency converters KEB, OMRON, DELTA, VESPER, OPTIMELECTRO and will help you choose a frequency converter for both single-phase and three-phase motors.