What Is a PID Controller? Principles, Structure & Real Industrial Applications (2025)

In every modern factory—from steam systems, compressed air, HVAC, chemicals, food and beverage to pharmaceuticals—the PID Controller plays an extremely important role in keeping systems stable, safe, and energy-efficient.

A PID controller is considered the “brain” of an automation system. It continuously maintains the Process Value (PV) close to the Setpoint (SP), minimizes fluctuations, and optimizes overall performance.

This article from Phuc Minh Engineering Co., Ltd. will help you clearly understand:

• What a PID Controller is

• Its structure and working principles

• When your plant should use a PID

• Real industrial applications: steam – water – air – temperature – flow

• Key benefits of PID control

• How to select the correct PID controller for industrial use

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✅ 1. What Is a PID Controller?

A PID Controller (Proportional – Integral – Derivative) is an automatic control device used to maintain stable pressure, flow, temperature, water level, and many other process variables. It does this by continuously calculating the error value and adjusting actuators such as:

• Linear control valves

• Pneumatic control valves

• VFDs (Variable Frequency Drives) for pumps and fans

• Heaters and electric heating elements

• Servo motors

A PID controller ensures the system operates with stability – precision – energy efficiency, especially in processes requiring high accuracy.

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✅ 2. Why Do Factories Need PID Controllers?

PID is the most widely used control standard in industrial automation (over 90% of systems today). Reasons include:

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⭐ 2.1 Minimizes System Oscillation

Without a PID controller:

• Pressure can spike suddenly

• Pump flow fluctuates continuously

• Temperature swings widely → directly affecting product quality

PID provides smooth, stable, non-lagging control.

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⭐ 2.2 Optimizes Energy Consumption

High-energy-consumption systems include:

• Boilers

• Air compressors

• Pressure boosting pumps

• Chillers

With PID tuning:

➡ Plants can save 8–20% energy every month.

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⭐ 2.3 Improves Product Quality

In food, pharmaceutical, and chemical industries, even a 1–2°C temperature deviation can ruin an entire batch.

PID control keeps process values consistently stable.

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⭐ 2.4 Extends Equipment Lifespan

Valves, pumps, motors no longer operate with sudden ON/OFF actions → reduced breakdowns.

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⭐ 2.5 Compatible With Almost All Industrial Devices

PID controllers can work with:

• Analog signals (4–20mA, 0–10V)

• Digital signals

• Relay on/off

• Modbus RS485

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✅ 3. Structure of a PID Controller

A standard industrial PID controller consists of:

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✅ 1. Central Processing Unit (CPU)

Calculates the control output using the P–I–D algorithm.

✅ 2. Input Section

Receives sensor signals:

• Pressure: 4–20 mA

• Flow: pulse / analog

• Temperature: PT100, Thermocouple

• Level: ultrasonic, radar

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✅ 3. Output Section

Controls actuators such as:

• Linear valves: 4–20 mA

• Pneumatic valves: 3–15 psi

• VFDs: 0–10V

• Relay ON/OFF

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✅ 4. Display Panel

Shows PV, SP, and Output %.

✅ 5. Parameter Settings

Allows adjustment of:

• Setpoint

• Kp, Ki, Kd

• Deadband

• Ramp-up / Ramp-down

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✅ 4. Working Principle of a PID Controller

PID calculates:

Output = P + I + D

Where:

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✅ P – Proportional

Responds to the immediate error between PV and SP.
Larger error → stronger corrective signal.

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✅ I – Integral

Eliminates long-term, accumulated error.
Ensures PV meets SP precisely.

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✅ D – Derivative

Predicts future system behavior.
Reduces overshoot and stabilizes transitions.

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➡ The combination of all three provides smooth – fast – precise – stable control.

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✅ 5. Real Industrial Applications of PID Controllers

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⭐ 5.1 Pressure Control for Pressure Reducing Valves (PRV)

PID reads outlet pressure and adjusts:

• Linear valves

• Pilot-operated control valves

Used in:

• Steam systems

• Compressed air

• Gas, N₂, CO₂

Keeps pressure stable within ±0.05 bar.

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⭐ 5.2 Flow Control for Industrial Water Pumps

PID + VFD enables:

• Smooth pump speed adjustment

• Reduced system stress

• 20–35% electricity savings

Applications:

• Industrial water supply

• HVAC – Chiller systems

• Food & beverage plants

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⭐ 5.3 Boiler & Furnace Temperature Control

PID keeps combustion temperature stable.

Benefits:

• Fuel savings

• Reduced soot

• Steady steam output

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⭐ 5.4 Closed-Loop Control Systems

PID is the core of all closed-loop processes:

• pH control

• Level control

• Fan speed control

• Humidity control

• Motor speed control

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✅ 6. Key Benefits of Using PID in Industrial Plants

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✅ 7. How to Select the Right PID Controller

✅ 1. Type of process

• Pressure

• Flow

• Temperature

• Level

✅ 2. Input type

• 4–20 mA

• PT100

• Thermocouple

• Pulse

✅ 3. Output type

• 4–20 mA (analog)

• Relay

• Pneumatic

✅ 4. Preferred manufacturers

Common brands:

• Omron

• Autonics

• Yokogawa

• Siemens

• ABB

✅ 5. Noise immunity & stability

Critical for steam and compressed air applications.

✅ 6. Technical support team

Phuc Minh provides:

✅ PID selection consulting
✅ Kp–Ki–Kd tuning guidance
✅ Installation – commissioning – calibration
✅ SCADA integration

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✅ 8. PID Controller – The Optimal Solution for Industry 4.0

PID controllers are essential in modern automation:

• Energy saving

• Fewer system failures

• Increased productivity

• Higher product quality

A plant without a PID controller operates “by feel”—inefficient, unstable, and uncompetitive.

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✅ 9. PID Controller Consultation – Contact Phuc Minh

PHUC MINH ENGINEERING CO., LTD.

📞 Hotline: 0902 800 728 – 0907 450 506
📧 Email: info@pm-e.vn

🌐 Website: https://pm-e.vn