I have an existing circuit which controls a pump motor. A PLC output energizes the control voltage to turn the pump on.
A timing relay allows the motor to start for 10 sec. then opens the circuit.
A flow switch contact is in parallel with the relay contact to hold in the circuit as long a flow is active.
When flow stops, the control circuit is opened.
My problem is that the circuit then tries to restart and the start sequence is initiated again.
How can I add a reset into this circuit, when it has no power until the PLC tells it to start.

 

What input condition does the PLC turn the pump on?

What is calling for pump on?

 

You need a low level switch on your fluid reservoir. That switch needs to be in series with pump control relay. We want this switch to open, when reservoir is empty.

Make any sense?

 

My problem is that the circuit then tries to restart

Is the PLC still energising the control voltage at that point? If so, it needs a change in the program.

 

If we knew more about the setup, we might put reservoir condition in the input rung. If it has a reservoir.

It's hard to tell what all it could effect.