PLC stands for Programmable Logic Controller.
It is a specialized industrial computer used to control machines, processes, or entire plants in industries such as oil & gas, petrochemical, power, manufacturing, and automation.
Key Points about PLC:
- 🔹 Programmable → You can write and change logic (programs) according to process requirements.
- 🔹 Logic → It executes logical decisions like ON/OFF, Start/Stop, open/close, etc.
- 🔹 Controller → It continuously monitors inputs and controls outputs to achieve desired operation.
Basic Working:
- Inputs (Sensors/Signals): PLC receives signals from devices like switches, transmitters, sensors.
- Processing (Program): It runs a pre-written program (ladder logic, function block, structured text, etc.).
- Outputs (Actuators): PLC sends commands to devices like valves, motors, alarms, pumps.
Advantages:
- Reliable and robust for industrial environments.
- Easy to program and reprogram.
- Can handle complex interlocks, sequences, and safety logic.
- Integrates with SCADA/DCS for monitoring and control.
👉 Example: In an oil & gas plant, a PLC may control compressors, pumps, level systems, or emergency shutdowns (ESD systems).