sundaysfantasy
Member
I recently started to work as a PLC programmer at a local pump manufacturing company. Among other projects, the most I deal with are wastewater pumping stations that use two pumps to empty the tank.
Before working here, I did a few similar projects and the solution was simple: start one pump at a preset level, stop it when tank empty, start the other when it fills up again. Pumps were not controlled via VFD so no further control was necessary.
Now however, most of the pumping stations have VFDs controlling the pumps and the only thing I do with those VFD besides soft starting the motor to nominal frequency is testing for clogs.
I recently came across a control system for this type of pumping station that has a high efficiency mode which means, from what I managed to understand, that it varies the rpm in order to reduce power consumption while keeping the pump on it's curve. So I started researching ways to do this, but the math is killing me.
I have the following information: a graph of the pump curve and efficiency, level of the tank and the out flow of the station.
My question is, how can I use the graph and flow in order to find a suitable control method for my pump using the VFD in order to reduce power consumption? Is there a math formula to calculate a parameter that needs to stay constant?
here's the graph: https://ibb.co/Y3jZSkv
Before working here, I did a few similar projects and the solution was simple: start one pump at a preset level, stop it when tank empty, start the other when it fills up again. Pumps were not controlled via VFD so no further control was necessary.
Now however, most of the pumping stations have VFDs controlling the pumps and the only thing I do with those VFD besides soft starting the motor to nominal frequency is testing for clogs.
I recently came across a control system for this type of pumping station that has a high efficiency mode which means, from what I managed to understand, that it varies the rpm in order to reduce power consumption while keeping the pump on it's curve. So I started researching ways to do this, but the math is killing me.
I have the following information: a graph of the pump curve and efficiency, level of the tank and the out flow of the station.
My question is, how can I use the graph and flow in order to find a suitable control method for my pump using the VFD in order to reduce power consumption? Is there a math formula to calculate a parameter that needs to stay constant?
here's the graph: https://ibb.co/Y3jZSkv
Last edited: