Water supply system with frequency control and auto-constant pressure which consists of frequency converter,soft starter and programmable controller(PLC) was introduced.Controllable multi-operating mode of PLC in this system was adopted to complete the alternation among different pumps;the converter controlled the speed of pumps,and the soft starter started up the high power pump stably to reduce the rush of current.If the converter fails,the soft starter will start up the pumps,thus improving the reliability of water.
A scheme to control mine shaft hoist system based on frequency converter was proposed.The paper introduced the basic structure of the lifting equipment,mine shaft hoist system controlled by frequency converter and its function.The new setting of shaft switch made the system more safe and reliable.It helps improve the work efficiency of mine shaft.
