Application of the hottest twidoplc in air cooled

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Application of twidoplc in air cooled heat pump central air conditioning

1 With China's faster and faster urbanization process, coupled with the continuous improvement of people's living standards, the demand for central air conditioning is increasing, and it has become a necessary equipment for cooling and heating of large-area buildings. In all kinds of buildings, central air conditioning system is extremely important in modern buildings, especially in modern intelligent buildings, central air conditioning system is an indispensable part. The central air conditioning system, which is made up of a large number of advanced equipment and corresponding supporting equipment, has become one of the important symbols of modern building technology and an indispensable infrastructure for modern buildings to create a comfortable and efficient working and living environment

at present, central air conditioners include fuel and gas-fired medium-sized central air conditioners, ground temperature central air conditioners, fully enclosed screw chillers, semi enclosed screw chillers and air-cooled chillers. Schneider Electric automation products have been successfully applied in fully enclosed water chillers, and it can be said that plastic enclosed air-cooled units and air-cooled heat pump units can be seen everywhere

air cooled heat pump unit

air cooled heat pump is a central air conditioning unit with air as cold (heat) source and water as cooling (heat) medium. As an integrated equipment with both cold and heat sources, air-cooled heat pump saves many auxiliary parts such as cooling tower, water pump, boiler and corresponding piping system. The system has the advantages of simple structure, low installation space, convenient maintenance and management and energy saving, especially suitable for areas lacking water resources. Therefore, the air-cooled heat pump unit is usually the preferred scheme in the HVAC engineering design of the year-round air-conditioning system, which is composed of many heating boilers, no heating at low speed, no high-speed heat, or other stable and reliable power supply. The centralized and semi centralized central air-conditioning system composed of fan coil unit, air-conditioning box and other end devices has the characteristics of flexible layout and diverse control modes. It is especially suitable for hospitals, shopping malls, hotels, apartments, factories, office buildings and other occasions

2. System control scheme

1) process description:

when the startup signal is valid, turn on the water pump of the system; Test the heating oil preheating cold and hot water polypropylene pipeline system gb/t18742.1, 2, 3 ⑵ 002 time (the preheating time for the first startup is greater than 8 hours); Check the water temperature after 60 seconds to determine whether the water temperature is in the loading area; Judge which compressor to start according to the running time and whether it is in fault state; Detect the status and restart time of each protection switch of the unit; 25% solenoid valve power on output, condensing fan operation output; After 15 seconds, the compressor star/delta starts; Time delay (25% - 50% load valve loading time): 50% solenoid valve is powered on for output, and 25% solenoid valve is powered off; Time delay (50% - 75% load valve loading time): 75% solenoid valve is powered on for output, and 50% solenoid valve is powered off; Time delay (75% - 100% load valve loading time) 75% solenoid valve is powered off; Delay the temperature control cycle to perform temperature judgment; The start-up process of a single compressor is completed; Load or unload other compressors according to the water temperature control

when the shutdown signal is valid, the 25% solenoid valve is powered on and output for 30 seconds, and the compressor is stopped; Stop the fan after 30 seconds, and 25% of the solenoid valve is powered off; Delay 60 seconds to stop the water pump; The shutdown process ends

2) control flow chart

3) system configuration

the system has 22 Di logic inputs, 21 do logic outputs and 7 analog inputs. Schneider twado PLC twdlcaa40drf (40 points, 24 inputs/16 outputs) is used as the control core of the system. Schneider twddmm8drt (4-way 24V input, 4-way relay output) and twdari8ht (8-way analog input, 10 bits, ntc/ptc, 50mA) are selected as the expansion modules. Schneider magelis HMI four line Chinese graphic display interface XBT N40 displacement sensor is mainly used to control the analog quantity in the production line of automation equipment


xbt n400+ twdlcaa40drf +twddmm8drt+ twddmm8drt +twdari8ht

twdari8ht module integrates 8 channels of analog input, has good humanized operation, and can achieve good temperature detection through simple configuration

3. Conclusion

1) under the condition of ensuring product quality, the new scheme adopts Twido PLC to develop a new ntc/ptc analog module with high integration, which greatly reduces the cost and effectively improves the competitiveness of the product

2) the new scheme uses a full set of Schneider products, such as XBT N400 text display and Twido PLC, which make the control system have good compatibility

3) the new scheme uses XBT N400 text display screen to preset and pretreat the process parameters of the system, which improves the processing accuracy and speed, improves the product efficiency, and thus ensures the overall performance of the system

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