Engr.Naveed

I m using MM430 VFD for a Siemens 18.5 kW motor...i am using PID to control the speed of vfd and a Donfoss pressure transmitter MBS 3000 range 4 to 20 mA at the analog input 1 in loop.....the problem is that when i run the VFD the analog current suddenly increases from 4 to 8 mA and10mA but the pressure is not so much that the analog current showing.plz help me how can i solve this problem so that pressure transmitter show the exact value of analog current according to the pressure when i run VFD

Engr.Naveed

Thanks alot Dear

Engr.Naveed

Thanks alot ...now my problem solved by acting upon ya advice.now plz tell me that how can i set PID for this vfd as i want to maintain the pressure 4 bar and the trnsmitter gives the 4 t0 20 mA accrosss 0 to 16 bar.i m using the motor with a pump for pumping of water and i want the 4 bar pressure to maintain in the line.and the 4 bar pressure(7.5 mA output from trnsmitter at 4bar) in the line is maintained at 50 Hz.so the analog current used for feedback is 4 to 7.5mA.now plz help me and tell me the complete parameter and their setting values for PID.i see another PID setting in the forum but they are not help ful.so plz help me as soon as possible.also tell me what is BICO

Engr.Naveed

Dear Ammy;
i am not using PLC im using built PID of the VFD MM430.i again describe that my feed backe signal will vary from 4 to 7.5 mA for the pressure 0 to 4 bar approximately.and the trnasmitter used give 4 to 20 ma for 0 to 16 bar.so i used the PID to build the pressure of 4 bar on the water line.and pump give the 4 bar pressure when the motor runs at 50 hz.so plz help me and tell me the parameter with the vaues.the transmittr is used is Donfoss MBS 3000 range=0 to 16 bar;output=4 to 20mA;
motor=18.5 kW