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VSD/VFD Pump Controller PLC

VSD/VFD Pump Controller PLC

(OP)
Dear Expert,

I have a question for certain condition as describe (commissioning step):

- a pump intent to serve multi-product of hydrocarbon. Let says product A and B. When the pump serve the Product A, the demand and certain capacity of the operation is satisfy. The pump using VSD to make power consumption effective and to make the rpm decreasing smoothly until the capacity of product reached.
- When the pump served the Product B ( different SG with product A ) the capacity demand of the operation is not satisfied (larger than demand requirement). We have done any trial and error to solve the problem, and we got one. We stop the pump suddenly by "mother" controller PLC. BUT it is not satisfied enough to do, because we need the smooth decreasing rpm of motor&pump to meet the certain capacity (consider life time of pump and power consumption efficiency).

Is there any suggestion or advice to solve my problem ? Maybe some of you ever met same problem that I am facing right now

RE: VSD/VFD Pump Controller PLC

Many VFD:s have inputs so you can select different sets of parameters depending on requirements. I know for sure that Siemens has that.

There are at least four parameter sets that can be chosen by inputting 00, 01, 10 or 11 on two terminals. That would make different ramp times possible and that would solve the problem.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: VSD/VFD Pump Controller PLC

Skogs is correct, most modern VFDs have selectable ramps rates that can be selected by toggling discrete inputs on the VFD. Alternately, if your PLC is controlling the VFD speed via (say) a 4-20mA signal to the drive, why not build variable ramp rates into the PLC?

RE: VSD/VFD Pump Controller PLC

(OP)
Thanks SKOGS and Groovy for the quick response, I will try your advice.

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