Pump Control

[simon Ong SK 0]

Hi anyone: I'm working on a project at a local car paint manufacturing plant. The Disperser will discharge mixed material using pump from upper flow to lower flow using a pump by mean of a inverter. The control is equiped with omron cj1m-cpu12+scu21+DI+DO+AO. The SCU21 is reading the Disperser load (Metler Toledo Indicator) and AO is for controlling the Pump Inverter. No Flow meter is attached to the system. The basic concept is like this: The system should by theory monitor the reduction of weight of the Disperser against a stipulated interval say 5 minutes. Then performed the calculation by mass divided with 5 minutes and then scale to the inverter according to the frequency of the pump (Max 60hz at 20ma). The problem I faced is the non linearlity of the pump which make scaling impossible. End user will enter the feedrate required (Kg/Min) from a PC. Then the PLC has to regulate according to the Target. I'm not using the PID Function (worry about hunting..as It will damage the sand mill) as a constant flow is required. Any one has this experience before on handling such problem?? Note: End user obtained the feedrate required by 1st manually adjust the inverter (weighed the flow out in 5 minutes manually). Thanks Simon

[ECSI 17]

Have a look at the Arithmetic Process APR(069) instruction. When set for Linear Extrapolation it can be used for non-linear scaling based on known setpoints along the X and Y axis.