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Split from Loss in Weight System.

Hello Siwarexi,

Thank you for your reply. 

I am just reconfirming below point from my earlier post:

5.  We will execute ' Device Characteristic curve ( command 165 ). Hopper will be filled completely before execution of this command and based on the Analogue output of the FTC , screw feeder will discharge the material. Material will get discharged and relevant characteristics will be noted by FTC. 

We have to perform this command 165. Is it correct?

During execution of command  164 and 165, mA output of the FTC will change automatically to 7.2 mA and then to 13.6 mA. Material discharge would increase as per increment in this mA output. 

Hope this understanding is correct.

Do we have to give any DI to FTC-L module when filling is ON so that FTC-L automatically changes the mode from gravimetric to Volumetric. ?

During commissioning steps also ,under DR 7 we will keep 'Source for analogue output' parameter to 'PID - control output '. Hope this is ok while performing command 164 & 165.

When we give volumetric Dosing ( Command 157) then does it start dosing as per the set point set in Kg/hr ?

This is my first time on this system and thus such queries.

Hello Siwarexi,

I only have posted the above queries yesterday but was not logged in portal.

Further to above queries , We also wish to know whether we should set the flow rate in Kg/Hr in DR 20 before performing command 164 & 165 or we can perform command 164 & 165 irrespective of flow rate set in DR 20.

Hello Siwarexi,

Thank you once again for your detailed and clear replies.

After doing weight adjustment, we performed Device characteristic curve ( command 165 ) and PID parameter command 164.

It was was observed during command 165 that, flow rate was sometimes going on the negative side and sometimes on the positive side. Time unit selected is Seconds and flow rate during this 165 command was fluctuating between -0.6 Kg/s to +0.7 kg/s.  The total discharged quantity was around 28 kg during this command 165. Weight difference seen in FTC was also near around 27-28 kg.  What could be the reason of flow rate going on the negative side. Is it normal or we need to check something?

What is the method to verify the accuracy of this system ? Is it only the drop test or any other method we can have ? 

In this application, Hopper has been installed on 4 load cells. Below the hopper, a small rectangular compartment is there which is connected to the screw feeder. These is no gate/valve between hopper and screw feeder. Is this ok or is it going to cause any problem ?

Hello Siwarexi,

Thank you for your reply.

We checked flowrate 1 earlier and I understood later on that Flow rate 2 shall be observed as flow rate 1 is for internal purpose.

We tried to Gravimetric dosing for testing purpose but FTC went into volumetric mode automatically , flow rate shown by FTC was too high. So might be due to flow rate fault FTC had switched to Volumetric mode.

During the above mentioned material discharge, FTC was showing flow value in Kg/H for few seconds and it automatically started showing flow display as F ______ Kg/H ; it stopped showing flow. What could be the reason that it stopped showing flow rate ?

Setpoint was around 588 Kg/H and flow rate shown initially was around 3000 Kg/H.

In our application, four legged hopper has been installed on four load cells. Rectangular box under the hopper and screw feeder connected to rectangular box are mechanically isolated from the hopper. This rectangular box & screw feeder are not part of weighing assembly. Only hopper is being weighed by load cells. 

A flexible cloth has been used between hopper bottom and rectangular box. 

I guess this must be causing the problem.

Earlier we have checked the static weight output of the FTC by placing standard calibration weights on hopper and FTC was measuring this static weights correctly. 

Will FTC measure the flow rate in Volumetric mode as well ?

What path would you suggest ahead ?