Application on Constant pressure water supply system
Advantages
Saving electricity:The Significant advantages of variable frequency constant water supply system is saving electricity,can save electricity 10-40%.For single pump,discharge of water fewer,the savings more.
Reliable running:Variable frequency constant water supply system realize stable water pressure,inverter realize pump soft start,pump can switch from power frequency to variable frequency without current surge,prevent strike pipe network,avoid water over pressure and pipeline break.
Clean and saving water:Set water pressure in pipe network base on practical water demand,automatic control discharge of water,reduce leakage loss.System supply water in closed loop,pipe network diry pollution and periodic cleaning in pool.
Flexible control:Segmented supply,timed supply and manual choose.
Perfect self-protection function:New communal variable frequency constant water supply system with protection functions:over current ,over voltage ,under voltage,loss phase,trip,instantaneous power outage,overload,stalling,low liquid level,timed rotation control main pump.Full-automatic control,automatic running,no need people in pump house,just need periodic check and maintain.If one pump broke down,it will automatic send alarm information to upper computer,at the same time start spare pump an keep supply water.If automatic control system broke down,user can operate manual system and keep supply.
Increase of equipment life,protect stable grid:After using inverter, pump don’t long-term run by rated rotational speed ,reduce mechanical wear and failure rate,timed rotation control main pump function can automatic timed rotate main pump,ensure mechanical wear uniformly and avoid rust die,increase equipment life.Inverter run continuously variable,pump realizes soft start,avoid power current strike motor coil and grid,eliminate water hammer effect.
System scheme
First system scheme:one inverter control one pump.Feedback signal based on water pressure,inverter account by own PID automatic regulate output frequency,change motor rotation speed for keeping constant water pressure,just one closed loop.
Second system scheme:One inverter controls several pumps.Use constant pressure supplier ,when inverter automatic runs,contactor of 1# pump motor will be connected,output frequency of inverter increase,at the same time pressure signal from pipe network increase,pressure signal from discharge pipe network and set signal from constant pressure supplier PLC pipe network together negative feedback to closed loop.When output frequency of inverter increase to maximum ,but pressure of pipe network can’t achieve setting requirement,inverter immediately control power frequency and connect 1# pump, 1# pump runs full speed,at the same time inverter via time delay variable control 2# pump.When pressure of pipe network and set pressure achieve basic balble control 2# pump.When pressure of pipe network and set pressure achieve basic balance,inverter control variable frequency motor keep on existing frequency.When water demand decrease,pressure of pipe network increase,output frequency of inverter decrease.When output frequency of inverter decrease to 0Hz,pressure of pipe network higher than set pressure within set period,inverter switch off existing variable controlled pump,turn to control next power frequency motor,in this process gradually rotate use pumps,use ratio of every pump equal and increase the reliability of system.
Basic wiring diagram
