What frequency conversion speed control water supply? What is the basic principle of frequency conversion speed control water supply?
At present, the frequency conversion and speed regulation of domestic water supply is more and more widely used in building water supply. The main reasons are:
(1) The water supply pressure of the frequency conversion speed control water supply is adjustable, which can easily meet the needs of various water supply pressures. In the design stage, the requirement for the accuracy of the water supply pressure calculation can be reduced, because the water supply pressure can be easily changed at any time. But it should be noted when selecting the pump, the pump head should be larger, because the maximum pressure of variable frequency speed regulation is limited by the water pump. The minimum working pressure should not be too small, because the pump is not allowed to work under long-term overload at low head and large flow. Otherwise, the capacity of the inverter and the pump motor should be increased to prevent overload.
(2) At present, the inverter technology is very mature. There are many domestic and foreign brands of inverters on the market, which provides a sufficient technical and material basis for variable frequency speed water supply. Inverters have been widely used in various sectors of the national economy. Any brand of frequency converter can be combined with a frequency conversion water supply controller to achieve constant pressure water supply with multiple pumps in parallel. Because of the wide application of building water supply, some inverter design manufacturers directly use the inverter water supply controller in the special inverter for water supply; this inverter has the advantages of good reliability and convenient use.
What is the excellent energy-saving effect of variable frequency speed regulation and constant pressure water supply?
Variable frequency speed regulation and constant pressure water supply have excellent energy-saving effects.
From the principle of water pump-pipe water supply, there are two methods in principle to adjust the water supply flow; one is throttling adjustment, and the water supply valve is opened to increase the flow; when the water supply valve is closed, the flow decreases. The second method to adjust the flow rate is to adjust the speed. The speed of the water pump increases, and the flow of water supply increases; the speed decreases, and the flow decreases. For occasions where the water flow often changes (such as domestic water), the speed is adjusted to adjust the flow, which has excellent energy saving. effect. The energy-saving effect of variable frequency and constant pressure water supply mainly depends on the change of water flow and the reasonable selection of water pumps. In order to make variable frequency and constant pressure water supply have excellent energy saving effects, the variable frequency and constant pressure water supply should adopt the water supply mode of multiple pumps in parallel. From the theory of multi-pump parallel constant pressure variable frequency water supply, it can be known that multi-pump parallel constant pressure water supply, as long as one of the pumps is a variable frequency pump and the rest are all industrial frequency pumps, constant pressure variable water supply can be realized. In the variable frequency constant pressure variable water supply, the flow rate of the variable frequency pump is changed. When the variable frequency pump is the largest of the parallel pumps, the constant pressure water supply can be guaranteed.
With multiple pumps connected in parallel for constant pressure water supply, the design can achieve the same efficiency of each power frequency pump under constant pressure conditions (due to the same working conditions), and make it work in a high efficiency zone, and the flow rate of the variable frequency pump is changing , Its work efficiency changes with the flow rate. Because of the use of multiple pumps in parallel for constant pressure water supply, the power of the variable frequency pump is reduced, which can reduce the energy consumption of the multiple pumps in parallel variable frequency constant pressure water supply system and improve the energy saving situation.
When the multi-pump parallel constant pressure water supply system adopts a frequency converter with automatic sleep function, when the water flow is close to zero, the frequency conversion pump can automatically sleep and stop the pump, so that the pump can be automatically stopped when no water is used, and there is no energy loss. The energy-saving effect.
The working mode of multi-pump parallel variable frequency constant pressure variable water supply is usually this: when the water flow is less than the flow of a pump under the condition of power frequency and constant pressure, a variable frequency pump is used to adjust the speed and constant pressure water supply; when the water flow increases, The speed of the variable frequency pump automatically rises; when the speed of the variable frequency pump rises to the power frequency speed, in order to further increase the water flow, it is controlled by the variable frequency water supply controller to automatically start a power frequency pump and the flow rate provided by the power frequency pump is constant (Flow rate under power frequency speed and constant pressure), the other parallel power frequency pumps are put into operation according to the same principle.
In the case of water supply with multiple pumps in parallel with variable frequency constant pressure variable, when the water flow rate decreases, the speed of the variable frequency speed control pump decreases (the frequency of the inverter power supply decreases); when the frequency drops to zero flow, the frequency conversion water supply controller sends an instruction, Automatically shut down a power frequency pump to exceed the parallel water supply. In order to reduce the impact (hydraulic or current impact) when the power frequency pump is automatically switched on or exceeded. When it is put into use, the speed of the variable frequency pump will automatically decrease, and then slowly increase to meet the requirements of constant pressure water supply. When exceeding, the speed of the variable frequency pump should automatically rise, and then slowly fall to meet the requirements of constant pressure water supply. The above frequency automatically rises, and the fall is controlled by the water supply frequency converter controller.
Another variable frequency water supply mode is usually called constant pressure variable cycle start and first start first stop working mode. In this water supply mode, when the water flow is less than the flow of the variable frequency pump at constant pressure and working frequency, the variable frequency pump will automatically adjust the speed for water supply. When the water flow increases, the speed of the variable frequency pump will increase. When the speed of the variable frequency pump rises to the power frequency speed, the variable frequency water supply controller controls the water pump to switch to the power frequency grid directly (not supplied by the frequency converter). The frequency converter additionally starts a parallel pump to work. As the water flow increases, the remaining parallel pumps are soft-started in the same way as above. This is the cyclic soft start input method.
The variable-frequency constant-pressure water supply system uses a potentiometer to set the pressure (the internal panel pressure can also be used), a pressure sensor (feedback is 4-20mA) to detect the pressure in the pipe network, and the pressure sensor sends the signal to the inverter PID loop After the PID loop is processed, it sends a water increase or decrease signal to control the motor speed. If the pressure is still insufficient or excessive within a certain delay time, another water pump can be started by the frequency converter to switch between power frequency and frequency conversion to make the actual pipe network pressure consistent with the set pressure. With the reduction of water consumption, the frequency converter automatically reduces the output frequency or cuts off the water pump, achieving the purpose of energy saving.