Research On Inductance Measuring Instrument For Large-scale Rotating Machinery Rotor Fault Diagnosis

The production security issues, especially production equipment's security receives people's attention, the mechanical device fault diagnosis technique is a new technique emerges gradually when the people is getting higher and higher request to the equipment security. The rotor control rod position's driving mechanism which circles by the coil is the large rotating machinery's key component. The driving mechanism normal operation directly related to large rotating machinery's normal operation. Because the large rotating machinery rotor the power is big, the rotational speed is high, the current capacity is big, the pressure is high, the structure is complex, the monitoring device is many, the movement and the overhaul request high, therefore if the design, manufacture, installment, overhaul, movement and so on has improper slightly, can bring the unit happened all sorts of fault when its run. Therefore, completes the large rotating machinery rotor's condition monitor and the fault diagnosis work, to avoids the equipment damaged in the accident, reducing the number of engine off times and reduce downtime, reducing the enterprise's economic loss is very essential. This paper aims to integrate advanced computer, electronics, information processing and mechanical design process, research and develop a high-precision inductance measuring instrument for large-scale rotating machinery rotor fault diagnosis, provides the fault diagnosis technology for this kind of large-scale mechanical device, and safeguard the mechanical system's reliability.In this paper, uses through measuring the inductance of the coil to detect the opening distance of a rotating machinery, to determine whether the large rotating machinery had been a fault. The instrument aimed at the large rotating machinery's operational factor to design electronics units especially such as automatic switch, electric discharge examination, inductance measuring unit and so on. The automatic switch unit through selects the new light pair relay to switch the large rotating machinery's coil with the instrument and power connections, this switch electric circuit has a high degree of isolation, fast response time characteristics. The inductance measuring unit uses the popular vector voltage - electric current method to measure the inductance in the smart instrument now, reduced the measuring time greatly, enhanced the accuracy of the measurements. At the same time, because the rotor opening distance and the inductance quantity has not explicit mathematical relation, therefore on the software through the curve fitting established the relations between the coil inductance change quantities with the rotor opening distances.The main research results are as follows:1. Has developed the automatic switch circuit for the large-scale revolving machinery rotor, had guaranteed the instrument does not interfere with the organization normal work when fault diagnosis.2. Has developed the inductance measuring unit, adopt the popular vector voltage - electric current method, enhanced the accuracy of the measurements and reduced the measuring time.3. Selected the ARM and the FPGA two pieces of chip constitute the control core, increased the system's control capability.4. Based on the hardware, has developed the software with a friendly man-machine interface, and has established the regression equation between the inductance change quantity and the rotor opening distance.After the prototype completes, carried on the performance test to prototype, the experimental result had indicated that when carried on the measure to the standard inductance, the instrument relative error was smaller than 3.8%, continuously measure many times, obtains system's relatively standard deviation is 0.14%. Through the regression analysis between the actual inductance change quantity and the rotor opening distance demarcate data, obtains the regression error is smaller than 0.3. When measure the actual revolving mechanical rotor opening distance, the error is smaller than 0.5, satisfies the request that rotor open and close distance error is smaller than 0.5.