Research And Realization Of Asynchronous Motor Fault Diagnose And Protect Device

The AC motors are extensive used in coal mine production, because of the execrable working conditions and so on, motors are always burnt. Not only caused direct economic losses, but also affect coal production. So to change this situation is very urgent, to strengthen the motor protection is a strong technical measures to change this situation.After researching the electric shearer manufacturer, the current motor fault diagnosis and protection system's deficiencies and problems, through analyze the common motor fault characters, I design based on the S7-300 PLC motors fault diagnosis and protection device.This paper combines the analysis theory of power system fault and symmetrical components method, put forward a method based on positive, negative and zero sequence current component to research the motor fault characters. It provides a tool and a theoretical foundation to research the motor fault characters.Through in-depth study the causes of common motor faults, fault mechanisms and fault characters, i command the abnormity character under various fault conditions, put forward the fault diagnosis and protection solution method. There are temperature fault protection, inverse-time overload fault protection, locked rotor fault protection, short circuit fault protection, based on negative sequence current fault detection phase fault protection, based on the external DC source of the leakage fault protection. The motor overload fault inverse-time protection algorithm can based on overload current fluctuation to make corresponding adjustment, overcome the shortcomings of receiving the effect of fault current undulation. This algorithm further improve the accuracy and reliability of motor overload protection, and it can provide the protection operation remainder time data to external monitoring systems, convenient for the user's operation, making more reliable, more user-friendly.According to the determined device functions, to select assembly, design and achieve the motor fault detection device's hardware and software parts, developed a touch screen display program, the device has a good interactive environment. through preliminary tests, to verify the design's feasibility and reliability. This design own consummate protection function, novel approach, simple wiring, and strong practical value.