外文翻译--PLC控制下的电梯系统.doc

PAGE 设计巴巴工作室 Elevator System Based on PLC Composed by the order of relay control system is a realization of the first elevator control method. However, to enter the nineties, with the development of science and technology and the widespread application of computer technology, the safety of elevators, reliability of the increasingly high demand on the relay control weaknesses are becoming evident. ?? Elevator control system relays the failure rate high, greatly reduces the reliability and safety of elevators, and escalators stopped often to take with the staff about the inconvenience and fear. And the event rather than taking the lift or squat at the end of the lift will not only cause damage to mechanical components, but also personal accident may occur.  Programmable Logic Controller (PLC) is the first order logic control in accordance with the needs of developed specifically for industrial environment applications to operate the electronic digital computing device. Given its advantages, at present, the relay control the lift has been gradually replaced by PLC control. At the same time, AC variable frequency motor speed control technology, the way the lift drag speed has been a gradual transition from DC to AC frequency converter. Thus, PLC control technology increases VVVF Elevator modern technology has become a hot industry. 1. PLC elevator control advantages (1) used in elevator control PLC, with software for automatic control of lift operation, reliability greatly increased. ?(2) layer was removed and a majority of the relay, the control system structure is simple, to simplify the external circuit. ?(3) PLC can be a variety of complex control system, easy to add or change control functions. ?(4) PLC can be automated fault detection and alarm display to improve the operation of security and ease of maintenance. ?(5) for the group control the allocation and management, and improve the efficiency of elevator operation. (6) do not need to change the c