In my (process) plant, a temperature controller is used to regulate the temperature of a heater. The controller sends signal to a relay and once the relay is energised, a signal is sent to a solenoid valve which opens and supplies gas to the main burner of the heater.
Now recently operators reported that the heater was firing erratically and the relay goes on and off intermittently.
In the course of our troubleshooting, we discovered that a control cable inside the solenoid valve was almost completely disengaged. We terminated the cable properly. Also the temperature controller was displaying well when we started troubleshooting, but as we powered it again after initially removing source of power from it, the controller was not displaying well again. Hence we had to change the controller and the system responded perfectly well.
My question is:
Was the partial contact in the solenoid valve responsible for the on-and-off observed in the relay. If yes, is there a feedback mechanism that communicates the status of the solenoid valve to the relay or is it a one-way communication pattern whereby the solenoid valve can cut off on its own without affecting the relay.
Kindly assist
Now recently operators reported that the heater was firing erratically and the relay goes on and off intermittently.
In the course of our troubleshooting, we discovered that a control cable inside the solenoid valve was almost completely disengaged. We terminated the cable properly. Also the temperature controller was displaying well when we started troubleshooting, but as we powered it again after initially removing source of power from it, the controller was not displaying well again. Hence we had to change the controller and the system responded perfectly well.
My question is:
Was the partial contact in the solenoid valve responsible for the on-and-off observed in the relay. If yes, is there a feedback mechanism that communicates the status of the solenoid valve to the relay or is it a one-way communication pattern whereby the solenoid valve can cut off on its own without affecting the relay.
Kindly assist