Electric Parameter Monitoring System Design Of Commercial Central Air Conditioning

Commercial central air-conditioning test lab always has kinds of testing experiment for Different types of air-conditioning, for example, the compressor performance test, fan performance test, air-conditioning pipe fatigue test, the electric parameter test of air-conditioning and so on, but the electric parameter test of compressor and fan has not been taken seriously. The compressor and fan both are nonlinear load, besides their control circuit has lots of nonlinear components inside, all these can affect the power quality of grid, especially make the harmonic distortion degree increases, voltage and current mutation phenomenon may occur when the air-conditioning is starting or running. It is necessary to monitor the harmonic wave of compressor or fan at real-time to improve the quality of electric energy, In order to help engineers to analyze the causes of problem further, the real-time waveform of voltage and current should be recorded in time. Therefore it is very important to monitor the electrical parameters of commercial central air-conditioning.The electrical parameters real-time monitoring system is based on virtual instrument technology. According to the need, hardware parts choose the National Instrument’s voltage acquisition module NI 9205 and single slot chassis NI cDAQ-9181, and sensors of voltage and current; software part use the National Instrument’s graphical editing software LabVIEW(Laboratory Virtual Instrumentation Engineering Workbench);combining with the software and hardware to complete the electrical parameter monitoring of commercial central air-conditioning. This monitoring system can simultaneously monitor the whole machine’s voltage and current, multiple compressors and fans’ voltage and current, the power, three-phase unbalance and harmonic; it also can record waveform of voltage and current manual or timing.In addition, the index of the commercial central air-conditioning’s residual current have been marked in some developed countries, about this our country is still in the attempt stage. The parameters of residual current can reflect the quality of the design of air conditioning internal wiring, also reflects the quality of the products from another point, it can provide a reference basis for electrical installation personnel when they select a residual current protection device. So real-time monitoring of residual current has been added to the electrical parameter monitoring system.