The Profibus-based Motor Protection Devices

Motor is the most widely used dynamic equipment in all fields, whose method of protection has been payed closely attention for many years all over the world. Nowadays, as the fast development of the technology of computer and control theory, a new method of computer comprehensive motor protection has appeared, this has more powerful logic analysis character and function compared with the former motorprotection. At the same time, these new motor protections can record and analyse the faults. Further more, they can be connected by a network, for the purpose of being easily controlled. And, this direction of development has been the major direction of this realm. This paper begins the study of comprehensive motor protection based on this background.At first, this paper makes a presentation and comparison of the existing fieldbus, then analyses varieties of symmetrical and asymmetrical faults of motor. In the applied research, this paper use the theory of Symmetrical components method analyses varieties of symmetrical and asymmetrical faults of motor, and adopt the measuring method of negative and zero sequence. This comprehensive motor protection system uses LPC2214 32bits ARM as its CPU,making full use of it's powerful capture function to outside event and strong ability of treatment to signal to design a new type of motor protective device. This comprehensive motor protection system construct a PROFIBUS station using PROFIBUS protocol chip SPC3 and 89S52. Using the technology of PROFIBUS bus to build a communication network,making it from the traditional protective device changed to a new type of intelligent motor remote unit which having the function of measurement,control,fault diagnosis and communication.After the whole design of the protection system is completed, the single and united protection experiments are carried on. The results indicate that the design attains scheduled technical requirement.