Abstract
Elevator is the indispensable transportation instrument in the high constructions .It is used to carry passengers and goods vertically.In the traditional elevator control systems,we mainly adopt relay-contactor control system ,it exists some disadvantages such as too many contacts,high rate of malfunction, bad reliability and large bulk, etc. PLC not only can carry out logic of switch volume, but also has mathematics operation, data processing, movement control, analoy volume PLC control, communication in network and so on. For complicated control systems, using PLC can decrease a lot of middle relays and time relays, simplify control circuit greatly, improve the reliability of operation and the degree of automation, so it can be said that PLC can completely take place of relay-contactor control systems. PLC also has many characteristics such as strong function, price and function compare high; none of contacts and need not to go together with lines, high reliability, strong ant-interference ability; small bulk, low consumption, etc .So we can solve the above problems by adopting PLC control system which makes the function of elevators more safety, more convenient and more comfortable. AC twin - speed elevator has the characteristic of close configuration and simple maintenance.It adopts open-loop control ,which makes the circuitries more simple and the price low. What’s more, It adopts bow wave brake，energy waste brake and other manners to the AC elevator，which make the comfortable feeling and the stop precise degree more satisfactory, thus AC twin - speed elevator is preva lently used.This paper introduces the design course of electric control system of AC twin - speed elevator based on four floors.
Key words: AC twin - speed elevator； PLC； Control system
