Central air-conditioning energy-saving devices a status quo power central air conditioning system in general, the maximum load capacity of the central air conditioning system in accordance with the hottest, biggest load conditions to design, there is a considerable amount off, but in fact the system rarely work under these extreme conditions, according to the statistics, 95% of the time air-conditioning equipment running at 70% load fluctuations below, so the actual load can not reach full capacity, especially under the air-conditioning demand is small, the host load low, in order to ensure better operational status and higher operating efficiency, the host can change in a certain range according to the load is loaded or unloaded, but with the support of the cooling water pump and chilled water pumps are still running under high load condition, This will bring the following series of questions: excessive water so that the temperature difference between supply and return water system to reduce the deterioration of working conditions in host, causing a host of heat exchange efficiency decreases, the energy wasted; pump pressure, usually through valve opening degree adjusting pipe to adjust the flow rate of cooling water and chilled water, so there is a considerable loss of energy on the valve. As the central air conditioning cooling water, chilled water systems and low operating efficiency, greater energy consumption and the long-running case of, energy-saving technological transformation is absolutely necessary. 2. Central air-conditioning refrigeration / cooling pump speed of saving principle AC inverter technology controls the operation freezing / cooling pumps, central air-conditioning system is one effective way of energy saving. Pump load power and speed proportional to the third power, namely PαN3, where P is power, N for speed; visible with frequency control methods to reduce economic pump flow is very significant, as required reduced flow when the pump speed is reduced, the power required by the speed of its decline in motor cubic. For example: A. When the pump flow decreased by 10% (trace output frequency is 45Hz) the motor shaft power P '= (0.9) 3P = 0.729P that the saving rate 27.1% B. When the pump flow decreased by 30% (trace output frequency is 35Hz) the motor shaft power P '= (0.7) 3P = 0.343P that the saving rate 65.7% decline when the chiller load, the required water flow reduction, to reduce the flow of water through the motor speed control device to reduce the pump speed, the pump a corresponding reduction in shaft power, the motor input power is also reduced. When the amount of the increase with cold, cold machine load increases, the condenser out of the water temperature increases, the operating frequency of the inverter increases, the pump speed to accelerate, increasing the water flow to maintain a constant temperature difference. Vice versa. So as to achieve the desired energy savings. 3. Dr. Paul inverter power control principle by the central controller and temperature sensor module temperature refrigeration / cooling pumps, return water temperature and water temperature is read into memory, and calculate the temperature difference value; according to the temperature difference between the value and then control the drive speed, adjust the water flow, control the rate of heat exchange; temperature, and illustrate the indoor temperature is high, should improve the freeze / coolant pump speed, accelerate the freeze / coolant circulation speed and flow speed of heat exchange; otherwise the temperature difference small, then the indoor temperature is low, can reduce refrigeration / cooling pump speed, slow freezing / cooling water circulation and flow rate, slowing the rate of heat exchange to save energy; inverter start, stop, change the operating frequency and monitoring display data such as the inverter output power, output frequency, output current, output voltage is achieved by the frequency central controller 485 via the communication protocol. 4, the power control procedure of the drive to the upper frequency 50Hz, the lower frequency of the inverter is 30Hz (according to the situation may be), according to a diagram of the control curve, combined with advanced intelligent control technology burnt automatic mode control. When the temperature difference ≤1 ℃, the drive will run at 30Hz frequency, along with rising indoor temperatures, freezing / cooling return water temperature continues to rise, the operating frequency of the inverter is also automatically increases as the temperature difference between the rise high; (2) when the temperature difference ≥5 ℃, the inverter will run at 50Hz frequency, then an inverter has been unable to meet the control requirements; need to start M2 freeze / coolant pump (2nd pump), M2 startup process is complete After the regulation of chilled water flow, control the rate of heat exchange to achieve a constant temperature difference between the control and return the water; (3) When the temperature difference continues to rise and ≥5 ℃, you want to start M1, M2 freeze / coolant pump frequency operation conducted jointly regulate refrigeration / cooling water flow, control the rate of heat exchange to achieve a constant temperature difference between the control and return the water; and (4) if and when the temperature difference is reduced to ≤1 ~ 2 ℃, you can close one of a pump, to retain an inverter to run automatically, to achieve maximum energy savings. Freeze / coolant pump after the operation, the control system will automatically send out the Run Enable signal to the host, so as to ensure the risk of pipes freezing does not occur as a host boot operation, thus ensuring the frequency energy portion can be well with the entire central air-conditioning system operation. 5. The system uses the frequency characteristics of energy-saving equipment optimum excitation control, optimum excitation current adjusted so that the efficiency of the motor to be more greatly improved, and further to achieve energy efficient; equipped with touch screen human-machine interface, simple operation control various data display and intuitive; equipped with a programmable controller, RS485 communication module, saving / bypass switch automatically, easy to operate; built-in instantaneous power failure restart function and try to start the function, in the case of unattended, fully automated soft stop the pump and soft starting, can completely eliminate water hammer effect NM;; can always adjust the pressure in the pipeline to ensure that within the proper range; reasonable run, motors, pumps, couplings of life will run greatly improved; the saving rate freezing and cooling pumps in more than 20%, even up to 60%. 6, the application of various types of central air-conditioning refrigeration pumps, cooling pumps, cooling tower fan, air blower and so on.