An existing 4x100HP pump station with 5HP jockey pump was working properly while being controlled by a Modicon PLC. The problem arose when we replaced the jockey pump with a 25HP and re-programmed the PLC to the new configuration. Upon start-up, the 24vdc power supply fuse blew and the adu206 input module went up in smoke with due to a busted resistor. We replaced the module and power supply but coundn't run the station because the pressure reading from the transducer kept on displaying 200psi (the max on the PLC program). We tried replacing the psi transducer and flow sensor but still getting a 200psi readout. Moreover, the input module again goes out in smoke after a few minutes that the power is on. We would appreciate any feedback on the matter.

 

I will need to know everything that was done at the time the pump was replaced, every little detail. Send me a PO, I can be there in 1-2 days.

MJH

 

I'd take a wild guess and look at the way you installed the 25hp pump. Something is feeding line voltage or at least a difference in potential back to your card. A better guess would take more information.

Regards

cww

 

Sounds like you're getting PWM interference in the control wiring. I had that on a job where we cooked many of the Modicon I/O blocks pull-up resistors specifically on the digital inputs.
I would look at the earthing of the instalation first - here are some ideas.
Check out the earthing of the motor. It must be on the same earth potential as the drive and the supply transformer neutral.
Earth the neutral of the control voltage so that it is not floating.
Check that the control wiring is not close to the drive-motor cables. Presumably these were changed when the motor and drive were uprated?
Check how the motor and transducer is mounted and earthed. The transducer might be earthing the motor thru the pipes and its supply.
What is the make of the old and new drive?
Where does the control supply come from - a seperate isolating transformer or phase to neutral of the supply to the drive?

Best of luck

 

good evening Edcen

i would check the wiring to the VFD.I think you are getting a power feed back from the control board.
With VFDs use isolation relays to control the drive.

hope this helps.
best regards,
calvin smith
[email protected]