To ensure the automatic operation of the water supply in your home, the water supply pump must be equipped with automation. As a rule, the 50-gallon pressure tank that is used to supply water to a private house are single-phase pumps. A thermal relay is built into the windings of these pumps to cut off the power supply to the electric motor in case of overheating. To ensure automatic switching on and off of the pump, a single-pole pressure switch, a press control system, or a pump frequency control system are used. Electromechanical pressure switches or pressure switches are the simplest devices. The relay sets two pressure levels between which the water pressure in the system is maintained.
this is a block inside which springs are located, adjustable with special nuts. The water pressure in the water supply system is transmitted through a membrane or bellows. These transmitters either overpower the spring resistance (at maximum pressure setting) or weaken the spring (at minimum pressure). The springs make or break electrical contacts inside the relay.
When the minimum set pressure value is reached (usually less than 1.4 bar), the relay contacts close and an electric current flows to the pump that the relay controls. Water flows from the well to the tank. As soon as the pressure reaches the set maximum, the spring opens the contact, the electrical circuit of the pump is broken, and it stops pumping water. The standard relay can be set from 1 to 6 bar.
Typically, all pressure switches have a factory setting of pressure values - the relay is triggered to turn on the pump when it reaches 1.4 bar, and to turn it off – 2.8 bar. However, the characteristics of the pressure switch made it possible to set the difference between the pump on and off levels of at least 1-2 atm. Accordingly, the pressure in the water supply system fluctuated within the relay settings. Due to the incompressibility of water when the pump is off and water consumption in the system, the pressure drops rapidly, therefore, hydraulic accumulators are built into the pumping unit – metal tanks with a rubber membrane inside. Compressed air is pumped in from one side of the membrane, and water is pumped on the other side. The larger the volume of the stored liquid, the less often the pump is turned on.
Until recently, almost all inexpensive pumping units were of this design. The stations are assembled on the basis of almost any pump. However, modern water supply systems place increased demands on water supply. So, it is necessary to maintain the pressure in the system with minimal fluctuations. The next step was to install the electronic unit
to the station control system. A pressure sensor with an analog electrical signal is used as a sensing element. The electronic unit takes the sensor readings and issues command to turn the pumps on and off. This makes it possible to reduce fluctuations in water pressure in the system since it is easier to fine-tune the automation using electronics. However, the installation of accumulators is still required. This device is called.
this is a device for automatic control of the pump and its protection against “dry running”, Presscontrol turns on the pump when the pressure (due to the analysis of water) drops below the set value and turns it off – when the flow of water stops. If the water supply system is not equipped with a hydraulic accumulator, then the pump is triggered very often.
The press control has a built-in check valve, a control panel, and a power button, and can also be equipped with an operating status and malfunction indicator. The press control device is mounted in the water supply system directly on the pump or in the pressure pipeline and provides constant water pressure. If the pressure in the system must be kept constant, then the best solution is to use
Frequency regulation of pumps
allows you to accurately maintain the pressure in the water supply system, without failures and a water hammer. The principle of frequency control consists of changing the speed of the variable pump, as a result of which a smooth change in the pump head is possible. An analog pressure sensor measures the pressure in the system. Based on the signals from the sensor, the control unit calculates the required increase or decrease in the pump speed in order to maintain a constant set pressure.
For stations with a similar control method, an emergency operation mode is provided, when, according to the signals of the backup automatic pressure switches, the station operation is ensured in the event of a breakdown of the frequency converter, although not in the frequency control mode. Hydraulic accumulators are included in the composition of such pumping units, but in this case, they remain in reserve and serve only to compensate for hydraulic shocks.
Since October 2005, DAB PUMPS SpA has been producing domestic pumping units with its own development – a complete pump frequency control unit ACTIVE DRIVER. Due to the inclusion of only the main functions in the control program, the price of the product turned out to be much lower than traditional frequency converters, however, the consumer properties of the pumping stations did not deteriorate. This design is used by EURO INOX AD, PULSAR DRYAD, JET AD, JETINOX AD units. It is necessary to adjust the required pressure once and the frequency converter will decrease or increase the engine speed and maintain the specified pressure in the system. Also, the frequency converter performs all the functions of protecting the electric motor.
Frequency converter advantages:
– maintaining a constant pressure in the water supply system, regardless of the flow rate and changes in the head before the pump;
– energy savings up to 60% by reducing the pump power and working with the highest efficiency;
– prevention of hydraulic shocks and pipeline breakthroughs due to smooth start and stop of the pump;
– complete protection of the pump in terms of electrical part;
– protection against dry running;