Process Interlocks and System Interlocks

Interlock is prerequisites need to satisfy & helps in smooth operation. Interlock are basically two kinds.

Process Interlocks:

Interlock which related / dependent on another Instrument / System. Example in line of Operation assume there is an Motor & Valve sequentially.

If we need to close a Valve located after pump, We have to OFF pump too along with valve closing (In order to avoid pressure accumulation in line). So we need to design a logic in PLC that pump should turn OFF when the valve is closed.

System Interlocks:

Interlock relevant to that individual system.

Suppose I made pump ON and didn’t receive the pump ON feedback , Then i need to de-energize with specified time period.

Author - Siva kumar