Core Concepts of PID Control
📌 PID controllers are the industrial standard for process control, used to maintain temperature, pressure, flow, or level automatically without constant human oversight.
⚙️ Manual Mode requires operators to constantly monitor and adjust control elements (e.g., valve position) every few seconds to maintain stability against changing process variables.
🤖 Auto Mode uses a PID controller to process analog sensor inputs (e.g., 4-20 mA or 0-10V) and automatically adjust outputs to maintain a precise setpoint with minimal deviation.

Application Examples in Automation
🌡️ Temperature Control: Specialized temperature controllers use inputs from thermocouples or RTDs and use a solid-state relay (SSR) or magnetic contactor to cycle a heater on/off to match the setpoint.
💧 Level Control (Pneumatic Valve): A level sensor sends an analog signal to the PID, which commands a pneumatic control valve to open or close precisely, balancing the fluid flow into a tank.
⚙️ Level Control (Motor/VFD): The PID controller sends an analog signal to a Variable Frequency Drive (VFD), which adjusts the motor speed to control the inflow/outflow, maintaining the desired tank level autonomously.

Advanced Integration and Tuning
💻 PLCs (Programmable Logic Controllers) can perform PID control using a built-in PID block, offering integrated control for more complex systems compared to standalone controllers.
🧠 VFDs with Built-in PID: Modern VFDs can eliminate the need for an external PID controller by reading sensor inputs, executing the PID algorithm internally, and controlling motor speed directly.
📊 PID tuning involves balancing P (Proportional) for present error response, I (Integral) for correcting past steady-state errors (offset), and D (Derivative) for predicting future error to smooth the response and reduce overshoot.

Key Points & Insights
➡️ Manual operation requires continuous operator engagement to make adjustments every few seconds or minutes to maintain stability, whereas Auto mode ensures precise, stable control.
➡️ Wiring a temperature controller involves connecting power (AC 220V to terminals 8 & 9), sensor input (thermocouple to terminals 5 & 6), and output to the SSR (terminals 2 & 3).
➡️ For motor control, the PID adjusts the VFD output signal (4-20 mA or 0-10V) based on the Process Variable (PV) compared to the Set Value (SV) to regulate pump speed automatically.
➡️ Effective PID tuning requires careful adjustment of P, I, and D values; for example, too much 'I' makes the system sluggish, while too much 'D' introduces noise.

📸 Video summarized with SummaryTube.com on Nov 20, 2025, 23:09 UTC