Connecting level switch


Thread Starter


I have a liquid level sensor, valves that control water flow into the tank, a pump controlled by a vfd, and data acquisition board. At what point do I connect the level switch if I would like to stop the pump and maybe also close the valve when the tank is full?

You haven't told us much about your objectives or the equipment you are using. This makes it difficult to answer your question. Are you using a PLC? Do you need to make sure the tank is full to the top? ..or just close to the top? Do you have remote control of the valves? The VFD?

If you use a PLC, you can use the level switch located at the top of the tank to send a command to the VFD to turn off the pump when the high level switch activates. You can also use a remote I/O multiplexer connected to the VFD directly via DeviceNet, ControlNet, or EtherNet/IP if both are Rockwell products. ...or PROFIBUS or PROFINET if they are both Siemens products. .. or Modbus or Modbus/TCP if they are both Schneider products.

Tell us more.
Dick Caro
If the pump is centrifugal pump, than stopping it would not stop the flow. You have to close the valve.
I'd recommend to do both actions.
For centrifugal pump: Valve first, Pump second
For gear/piston pump: Pump first, Valve second
I don't know. You don't say whether your VFD has such control inputs and outputs. If it does not, you need another component controller.
sorry for the slow response but i have the following

1. kobold nkp6401 limit switch
2. automation direct gs2 ac drive
3. EBVA1-1-1-150EPT-PV, Electrically Actuated Ball Valve

I would like to stop the flow when it is close to the top