Weak current College】 【frequency conversion water supply and basic principles of life-Power By】 【China power house network.

<br> current, frequency control in potable water applications in the building to the water, the more the more widely, mainly due to: <BR> <BR> 1.. Frequency of water supply water pressure adjustable, you can .easily meet the needs of a variety of water pressure.. In the design stage can reduce the calculation accuracy of the water pressure requirements, because any time you can easily change the water pressure.. However, should pay attention to selecting a pump, the .pump head should be larger, because the frequency control limits the maximum pressure by the pump.. Minimum operating pressure should not be too small, due to the low lift pump does not allow long-term overload of work under high flow, or should increase .the capacity of the drive and pump motors to prevent overload.. <BR> <BR> 2.. At present, the inverter technology is very mature in the market, there are many domestic and foreign brands of converter, which provided for .the frequency control water supply adequate technical and material basis.. Inverter has been widely used in various departments in the national economy.. Any brand of drive controller and frequency of water supply with, you can achieve more constant pressure water supply pumps in parallel. .. Widely used as water supply buildings, some drive manufacturers to design the controller directly to do in the frequency of water supply inverter water supply system; This drive has good reliability, ease of use advantages.. <BR> <BR> 3 ... Frequency control water supply has an excellent energy-saving effect <BR> <BR> a piped water supply by the principle of pump known to regulate the water flow, in principle, two ways; first throttle, opening a large water .supply valve, the flow increased;. off a small water supply valve, the flow decreased.. The second method is to adjust the flow speed adjustment, the pump speed increases, water flow increases; speed dropped, the flow decreased, the water flow .is constantly changing situations (such as water), adjust the flow with speed, with excellent energy-saving. effect.. National Science and Technology Commission and the State Economic and Trade Commission of China, "China Energy Technology Policy" in the pump .and fan speed control technology as the National Ninth Five-Year Plan focused on the promotion of energy-saving technology projects.. Should be noted that the effect of constant pressure water supply mainly depends on energy-saving changes in water flow and pump a reasonable .option, in order for constant pressure water supply with excellent energy saving effect, constant pressure should not be used for water supply and more pumps in parallel mode.. Constant pressure by a number of pumps in parallel multi-inverter supply theory shows that constant pressure .water supply pumps in parallel, as long as one of the pump is the pump, the rest is the pump frequency can be achieved constant pressure variable water supply.. When Constant Pressure variable water supply, pump flow is varied, when the pump is the .biggest pump in parallel, to ensure constant water supply.. More constant pressure water supply pumps in parallel, the design can be achieved under the constant pressure and constant frequency efficiency of the pump (due to the same conditions), and make it work in .high efficiency area, pump flow is changing., its efficiency as the flow rate change.. Pumps in parallel because of multi-pressure water supply, reduce the pump power, which can reduce the multi-pump system in parallel constant pressure water supply energy ., improve energy situation.. <BR> <BR> When multiple pumps in parallel with automatic constant pressure water supply system uses the sleep function of the inverter, when the water flow is close to zero, the pump will automatically stop the magnetic .sleep, which can be done automatically stop the pump without water, but not when. energy loss, has the best energy saving results.. <BR> <BR> Many variables constant pressure water supply pumps in parallel mode of operation is usually .like this: When the water flow is less than a pump frequency constant flow conditions, by a pump control water supply;. When the water flow rate increases, increase in pump speed automatic; When the pump frequency speed up to speed, the water flow .to further increase water supply by the inverter controller automatically starts pumping a frequency into the work. frequency of the pump provides flow is constant (constant-frequency speed of the flow), the rest of the parallel pumps frequency input by the same principle.. .<BR> <BR> Parallel in a multi-pump variable frequency constant pressure water supply, when the water flow decreased, fall speed of the pump frequency control (frequency converter supply drop); When the frequency drops to zero flow when the .frequency. supply controller issues a command to automatically turn off a pump to make it beyond the frequency of water supply in parallel.. To reduce the automatic input of the pump frequency exceeds the impact (the impact of water or current).. In investment ., the decline in pump speed automatic, and then rose slowly to meet the requirements of Water Supply.. Automatically increase the frequency, down by the water supply frequency controller.. <BR> <BR> Another constant frequency variable water supply mode .is often called the first open loop start and first stop of the operation.. In this supply mode, when water flows are less than pump flow under the constant frequency, by the automatic speed water pump, when water flow increases, the pump speed increased ... When the pump speed increases to the frequency speed controller to control the frequency of water supply pumps to switch to direct power from the grid frequency (not through the inverter power supply).. Frequency along the other one started to work in parallel pump ... With the water flow rate increases, according to the above the rest and the associated pump soft start into the same way.. This is the way into the soft-start cycle.. <BR> <BR> When the water .flow decreased, the parallel sequence beyond the pump frequency and pump out the order of input by the first principle of the first off the pump than single-board computer control by the inverter controller.. <BR> <BR> Seen from the .above variables constant pressure water supply for the inverter usually has two modes, one pump fixed mode, the second is the frequency loop soft-start work.. In the fixed frequency mode, the pump is based on parallel mode automatic frequency or excess.. .Because the pump is fixed, when the water flow changes, pump is always running, so the longest running pump.. In order to balance the water pump running time, for a fixed pump operation mode can be designed to pump regular rotation run.. .When a pump station that is run after a certain time, the inverter controller controls the rotation pump automatically.. For example: the start of a pump frequency ,2-3 pump frequency, when a pump frequency running time T (T can be set .in sequence) automatically pump rotation frequency of 2, 3-1 pump frequency, in this state run. automatically after a rotation of T 3 conversion, 1-2 pump frequency, ... ...... This rotation is repeated regularly ... <BR> <BR> Obviously, with automatic rotation of control pump variable frequency constant pressure water supply system, pump is the time to change that any one can become parallel pump pump.. Water supply from the constant pressure variable theory .shows that, in order to ensure constant water supply, pump must be the greatest in the parallel pump.. To this end, the constant pressure water supply and pump water machine automatically timed rotation, the parallel should be the same size of pump to ensure .constant water supply.. <BR> <BR> Works by the inverter, the inverter is not allowed in the operation of the switch in its output; otherwise the process will drive the switch some of the electronic devices are high current impact and .reduce its life ... Automatic rotation of the pump process, to switch the output of the inverter; in order to protect the drive, making the drive should be made before the switch automatically stop running.. In the drive to stop running conditions, .the switch in its output.. Restart the switch after a good drive and resume normal operation.. Therefore, the automatic rotation of the control circuit is more complex, will increase the frequency conversion control cabinet and reduce the cost of its reliability.. < .; BR> <BR> When the water supply system with constant pressure variable pump automatic rotation function, and its advantage is the parallel to the pump rotation frequency operation can be timed so that the balance of parallel pump wear.. However, the frequency .of sand in any one run, if the pump has the potential to drive failure protection trip and stop working.. The pump is controlled by the inverter parallel operation; when the inverter trips, this will bring down all the pumps in parallel interrupted water supply ... <BR> <BR> Therefore, when the reliability of ocean water, some with automatic rotation control function constant pressure water supply reliability will be lower than the water supply unit does not have the automatic rotation control function constant pressure water supply .unit.. The author believes that the reliability of water supply is the main contradiction.. We do not advocate the use of control functions with automatic rotation of Constant Pressure Water Supply System.. Multiple pumps in parallel, circular soft start Constant Pressure Water Supply .System, there are also the constant pressure mode of the shortcomings of automatic rotation.. In order to ensure constant water supply, also require the same size of the parallel pump.. <BR> <BR> Can be described fully in order .to ensure water supply reliability, the author does not advocate the use of auto-rotation and frequency loop soft-start mode.. Automation Engineering Department of Tsinghua Unisplendour Group in its "ABB Water Supply System User Manual" says, "loop soft .-start! This is a dangerous temptation to engage in constant pressure water supply a lot of enthusiasm on the development of this technology, but we recommend it. The. "We agree with the Department of Automation, Tsinghua Unisplendour Group, the academic view .of the above, not keen to engage in soft-start cycle frequency of water supply.. A water supply pipe from the pump <BR> principle we know that loss is equal to zero when the throttle, the water supply system has the best .energy-saving effect, this time complete consumption of the pump in the water supply head height and water loss on the flow resistance.. This frequency adjustment of water supply management state variable transformer as water supply, water supply systems in this head - flow rate .curve and the piping system flow resistance - flow curve overlap.. In an ideal transformer variable water supply system, in the water point, the lift constant, is constant pressure water supply.. In the actual construction, the water point many, not one ., it is difficult to determine where is the constant pressure of water points.. Variable transformer supply system is not universal, rarely used in engineering.. A practical variable transformer transformer supply system is called quasi-variable water supply system; water supply system in .the quasi-variable transformer, its constant value with increasing water flow increased hop bands.. For example, more pumps in parallel constant pressure water supply, when a pump work, the constant value is automatically changed P1 + ΔP1; when two, three, .four pump input, the constant values were automatically transferred into the P1 + ΔP2, P1 + ΔP1 + ΔP2 + ΔP3, ΔP4 ... .... ... One P1ΔP1ΔP2ΔP3, ΔP4 ... ... .... May .need to set up; Accordingly, prospective variable transformer system (device) is very close to the water supply characteristics of the ideal transformer can be variable water properties, with excellent energy saving effect, this water supply system (equipment.) has the versatility. .. For example, the internationally renowned ABB inverter water supply system to the quasi-variable transformer with water control.. <BR> <BR> Fact, in the construction of water supply among the quasi-variable transformer supply model is also rarely .used because in actual use, is difficult to give specific parameters.. <BR> <BR> <BR>..