The so-called machine under test mainly refers to a wide variety of rotating machinery, which refers to the compressor here. In order to make the measured signal accurately reflect the working condition of the compressor, the system arranges three test points on the compressor shaft, which are: one measuring point in the axial direction, two measuring points in the radial direction, and the radial measuring sensor. Installation as shown. The pick-up of the vibration signal pick-up vibration signal is completed by an eddy current sensor, and the probe of the eddy current sensor, the extension cable, the pre-positioner, and the object to be tested constitute a basic working system. When the distance between the measured metal and the probe changes, the Q value of the probe coil changes accordingly, and the change of the Q value causes a change in the amplitude of the oscillating voltage, and the oscillating voltage that varies with the distance is subjected to detection, filtering, and linear compensation. The amplification and normalization process is converted into a voltage change, and finally the mechanical displacement is converted into a voltage, and the typical output characteristics are as shown. Working principle of eddy current sensor Typical displacement voltage characteristic curve of eddy current sensor (φ11mm probe) This system adopts eddy current sensor 0D900803-03-04-20-00-060809 produced by Shanghai Ou Dan Instrument Co., Ltd. The eddy current sensor can be statically and dynamically Non-contact, high linearity, high resolution measurement of the distance of the metal conductor to be measured from the probe surface is a non-contact linearization measurement tool. The eddy current sensor accurately measures the static and dynamic relative displacement changes between the body and the probe end face. The data acquisition card system uses Advantech's multi-function data acquisition card PCI1711L, which has a higher performance-price ratio than other acquisition cards. The main performance indicators of the card are: 16-channel 12-bit A/D converter provides analog input, the sampling rate is limited to 100 kHz, the gain of each input channel is programmable, and the card has a 1K sampling FIFO buffer, programmable trigger/timer In addition, the board also has 16 digital inputs and 16 digital outputs, which can be used to control the monitored machinery and provide alarm signals. Because the vibration frequency of mechanical equipment is generally not very high, the PCI1711L can fully meet the requirements. The computer system data is converted from the PCI1711 capture card into the computer through AD conversion. The computer system analyzes, processes, displays, and stores the signals under the support of its powerful software and hardware environment to meet the requirements of the user for the detection system. Software system design The system software adopts Labview virtual instrument environment. Labview is a virtual instrument development platform launched by NI Company of the United States. It uses the powerful computing, display and connection and storage capabilities of the computer to build users' own instruments and instruments on the screen. The function of “software is instrument†is mainly applied to the fields of instrument control, data acquisition, signal analysis and display. It is characterized by the use of a standard instead of a text code to create an application, which has the characteristics of a flow programming language. The program is executed in the order of the flow of data between blocks, rather than a general-purpose programming language executing line by line. When the block program is written, as long as different function tags are selected from the function modules, the data can be transmitted by connecting the signal lines. The system uses the Labview6.0 platform and uses the Labview environment board developed by Advantech for NI. The card driver adds the PCI1711L standard to the Labview programming environment mouse shortcut menu, which provides convenience for programming. Sodium hydrosulfite is widely used in the textile industry for reducing dyeing, reducing cleaning, printing and decoloring, and for bleaching silk, wool, nylon and other fabrics. 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