How can I got a bettter performance in melt plastic control

Hello everibody,
I went to replace one 900 series controller by one 3504, it is used for pressure control for an extruder, the machine is currently working but the customer comments that he would like a better performance, the sensor measures from 0-5000 Engineering units (0-40mV) and the control is normally set at 900 engineering units but with an error of 50 wich is about 1% of the full scale but the customer says that he needs better regulatory control.

The cutomer works always at 900 and the high alarm is at 1750, so he will almost never will see more than the half of the full scale my question is the folllowing:

Currently the scalling is 0-40mV vs 0-5000 Eng units, IF i change the scalling to :
0-20mV vs 0-2500 Eng Units will it helps to get better regulatory control?

Any help to get an improvement of the tuning will be apreciated as well.
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  • Hi Marco,
    what kind of 900 series controller did you replace? It could have been a 902 up to a 988 ( 902S-904P or 900EPC ).
    The change of scalling would not change anything, the ratio IP/ OP is still the same.
    Basically it is usually a matter of the settings of the PID's. ( Besides haveing a look at the resolution and the sample rate of the IO's. )
    Do you know the PID's of the 900 and of the 3504?
    What kind of output is fit in the 3504?
    Rudi
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    Thanks Rudi, furtunally I dont ́t know the PID's, the 900 is damaged, it is a 942S., the pressure sensor measurement has a filter time constant of cero and the resolution is xxx(0), no decimals. with a bigger filter time constant the error is higher. The output is a DC module 0-10 volts and goes to the input of a drive, but the resolution is x(0). If I change to .x.x(1), x,xx(2) or x.xxx(3) or x.xxxx(4) would I ge a better performance?
    Thanks
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  • Hi Marco,
    it should be x.xx. That is the resolution, the DC OP Module can handle.
    Would you email the clone file to rudi.weiss@schneider-electric.com?
    Do you know the use of iTools - OPC Scope to record the values of SP, PV and OP?
    Rudi
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