Portable Measuring System Apply For Low-voltage Apparatus Testing

Low-voltage apparatus testing is one of the key step to detecting the quality of low-voltage apparatus and also the important basis to improve the design and develop the new products.It will help you find out the bugs of the products on time by verify whether the electrical products meet related standard and whether any defect bug exist will effect the normal operation of low-voltage apparatus,so it lays testing and analyzing foundation for researching of electrical failure mechanism by accurate collecting of testing parameters of low-voltage apparatus and also display the failure reason of products from the testing and will provide guidance to product design optimization.In order to improve the disadvantages based on PCI-6254 measuring system,such as:un-removable,extremely expensive and can not accurate display the dynamic process of segmented test wave-forms because of the low sampling rate.This article constructed a high sampling rate,high precision,large storage depth,low cost,easy operation and multi-channel synchronous,portable data acquisition system based on virtual instrument platform.The system can accurate testing and handling all kind of parameter for low-voltage apparatus,It is designed an easy maintenance and expandable functional module according to customer's actual demands to gather the accurate,fastlly and real-time main parameter in the process of low voltage electrical test.The research content on measuring system are as belows:(1):Expounds the significance and method of low voltage electrical test:mainly summarized the testing condition,testing basis,testing method,testing circuit and judgment of test results of short-circuit making,breaking-capacity test and electrical life test,and then expounds the constitute,design philosophy,performance index and measured parameters of measuring system,and also provided the basis for the design of measuring system.(2):It also designed the hardware system for measuring system.Deigned a voltage acquisition isolation module based on the linear optical coupling device HCNR200,This module with good linearity,accuracy and applicability,accomplished the result of separating force and weak electricity between input signal and output signal and set up current signal acquisition module by use of electric current transducer(Rogowski Coil),The adopted electric current transducer(Rogowski Coil)with a number of advantages,such as non-saturated,good linearity,outstanding transient respond ability,wide frequency band,big tested current range and no secondary open.According the discussion above,it is easy to tell that the hardware part of measuring system was consisted by current signal acquisition module,voltage acquisition isolation module,data acquisition card(IN)and controller(IN).(3):This article also designed software system for testing the low voltage electrical apparatus and expounded the experimental data processing method.Software system was set up by virtual instrument LABVIEW,It accomplished a number of functions,such as: parameter setting,waveform analysis of the spectrum,wavelet transformation and waveform display,storage and playback.Corrected the accuracy of measuring system,get the range of the waveform and energy distribution of spectrum by use of FFT and provide basis for low voltage electrical breaking process of electrical signal spectrum analysis,get the time which needed to generate transient current voltage distortion by wavelet transformation to determine the test time in arc,arc energy and Achieve the prediction of electrical life test failure under a certain condition.(4):This article also tested the frequency response of measuring system and researched the influence to contactor electric life by different sectional phase.By comparing the data collected by measuring system designed in this system and PCI-6254 measuring system and the measuring system consisted by oscilloscope and splitter,it will be easy to find out that the date get from PCI-6254 can not accurately reflect the dynamic process of low voltage electrical breaking because the low sampling rate,but the measuring system designed in this article and the measuring system consisted by oscilloscope and splitter have higher sampling rate and can test the real situation during the process of testing and also provide support to the theory of research voltage signal to electrical failure.Also did research on alternating current contactor's contact loss of electronic arc characteristic under the different sectional phase,such as: arc time and arc energy,the testing result shows when breaking current phase is a little less than 180 angle,it will longer the life time of electronic power contact.To sum up,the measuring system designed in this article with a lot of good characteristics,such as high sampling rate,low cost,portable and strong ability to process data and so on,it meets the parameters measurement and data processing requirements of low voltage electrical and provided basis for fault diagnosis and optimization design of low-voltage device.