Every roll forming machine relies on a precisely designed electrical control and wiring system. This system ensures that motors, sensors, drives, and hydraulic units operate in perfect synchronization to deliver accuracy, efficiency, and safety.

In this guide, we’ll break down the key wiring layout, main control panel components, and how everything connects — from the main power isolator to the PLC and sensors on the production line.

1. Main Power Supply and Distribution Circuit

The main power circuit distributes electrical energy from the facility’s supply to all critical parts of the roll forming line.

Key Components:

Main Isolator / Circuit Breaker: The main disconnect switch for the entire machine.
RCD / MCB / MCCB: Protects against overload and short-circuits.
Step-Down Transformer: Converts 380–415V 3-phase AC to 24V DC control voltage.
Power Busbars & Distribution Blocks: Supply power evenly to all drives and control units.
Grounding Busbar: Ensures operator and system safety.

Voltage Standards:

Industrial machines typically run at 380–415V AC, 3-phase.
Control circuits operate at 24V DC.

2. PLC and Control System Wiring

At the heart of every modern roll forming line is a PLC (Programmable Logic Controller).
It governs all sequences — from coil feeding to cutting.

Main Components:

PLC CPU & I/O Cards: Handle all machine logic and feedback.
Input Modules: Receive signals from sensors and switches.
Output Modules: Activate relays, drives, and solenoid valves.
HMI (Human Machine Interface): Touchscreen for operation and status monitoring.
Power Supply Unit (24V DC): Feeds PLC, relays, and sensors.

Common Connections:

Digital Inputs: Start, Stop, Emergency Stop.
Digital Outputs: Motor relays, hydraulic valves.
Analog Signals: Length sensors, pressure, or speed reference.
Communication Lines: Ethernet or RS485 between PLC, HMI, and drives.

Motor and Drive Circuit

The motor wiring system powers all movement in the roll forming machine — forming, feeding, cutting, and stacking.

Key Elements:

Main Drive Motor: Turns the forming rollers.
VFD (Variable Frequency Drive): Controls motor speed and direction.
Servo Drives: Manage flying shear or punching units with precision.
Hydraulic Pump Motor: Powers cutting or notching systems.

Control Flow Example:

PLC → Output Signal → Contactor → VFD → Main Motor

Each drive receives feedback from the encoder to synchronize cutting and feeding operations.

Sensors and Feedback Devices

Sensors are the “eyes” of the roll forming line, constantly feeding live data to the PLC.

Typical Devices:

Proximity Sensors: Detect sheet position or metal presence.
Photoelectric Sensors: Identify sheet ends or feeding gaps.
Limit Switches: Define travel limits for mechanical parts.
Encoder: Measures line speed and sheet length.
Pressure & Temperature Sensors: Monitor hydraulic systems.

Standard Sensor Wiring:

3-Wire Sensors: Brown (+24V), Blue (0V), Black (Signal).
Encoders: 5–6 wires (A, B, Z, +24V, GND).

Hydraulic and Pneumatic Circuit Wiring

Hydraulic and pneumatic controls manage forming dies, cutters, and punches.

Components:

Solenoid Valves (24V DC): Operate cylinders for cutting/punching.
Pressure Switches: Send status feedback to PLC.
Hydraulic Pump Starter: Controls pump motor through contactor and relay.

Typical Control Path:

PLC Output → Relay → Solenoid Valve → Cylinder Activation

6. Safety and Emergency Circuit

Safety circuits protect both operator and equipment.

Common Safety Devices:

Emergency Stop Buttons: Wired in series, normally closed.
Safety Relays: Monitor E-stop and interlock integrity.
Door Interlock Switches: Disable operation if the panel door is open.
Overheat Sensors: Protect motors and drives from high temperatures.
Alarm Indicators: Buzzer and signal lights for warnings.

Logic:
When an emergency stop is pressed → PLC output disables → main contactor drops → power to all drives is cut.

7. Communication and Remote Monitoring

Many roll forming lines now include remote monitoring and diagnostics systems for real-time support.

Typical Communication Setup:

PLC ↔ HMI: Ethernet or RS232.
PLC ↔ VFD / Servo Drive: Modbus RS485 or CANopen.
Remote Access Module: Ewon, PLCRemote.net, or similar device.
Ethernet Switch: Connects PLC, HMI, and external access modules.

This allows Machine Matcher engineers to provide remote troubleshooting and PLC code updates globally.

8. Main Control Panel Components (Full List)

Section	Main Components
Power Input	Main isolator, MCCB, RCD/MCB, surge protectors
Control Power	Transformer, 24V DC power supply
Drives	VFDs, servo drives, overload relays
PLC Section	PLC CPU, I/O modules, expansion cards
Safety Section	Safety relay, E-stop loop, interlocks
Hydraulic Control	Pump contactor, solenoid relays
I/O Field Wiring	Terminal blocks, labeling strips
Networking	Ethernet switch, remote access device
Cooling	Fans, filters, panel heater (if needed)

9. Panel Layout Overview

A properly designed panel separates:

Power section (left)
Control & PLC section (center)
Communication and safety section (right)

This ensures reduced electromagnetic interference and simplified maintenance.
Cable ducts, wire numbering, and grounding improve safety and compliance.

10. Recommended Wire Sizes

Circuit Type	Wire Size (mm²)	Voltage	Description
Main Power	6–25 mm²	380–415V	Motor and supply
Control Circuit	0.75–1.5 mm²	24V DC	PLC and sensors
Signal / Encoder	0.5–0.75 mm²	24V DC	Shielded cable
Communication	CAT6 / RS485	Low Voltage	Shielded twisted pair

11. Example Wiring Flow Diagram

[Main Breaker] → [RCD/MCB] → [VFD] → [Main Motor]
↘ [PLC + 24V PSU] → [Inputs/Outputs]
↘ [Encoder] → [PLC Input Module]
↘ [Solenoid Valves] → [Cutting System]

12. Optional Add-Ons for Modern Roll Formers

UPS Backup Unit: Prevents control loss during power flickers.
Data Logger or SCADA Gateway: Records production data.
Power Analyzer: Monitors energy efficiency.
Remote Camera Monitoring: Enables live view of machine status.
AI Diagnostics via Machine Matcher: For predictive maintenance and PLC fault analysis.

13. Maintenance Tips for Electrical Panels

Inspect cable connections monthly for loosened terminals.
Clean filters and fans to prevent overheating.
Check drive parameters after software updates.
Test E-stop and safety loops weekly.
Document wiring changes in the schematic diagram.

Conclusion

The electrical system of a roll forming machine is the backbone of precision, reliability, and safety.
From main power distribution to PLC automation, every wire and connection plays a critical role in ensuring the line runs smoothly.

A properly designed and maintained panel reduces downtime, simplifies troubleshooting, and extends machine lifespan.

Machine Matcher supplies fully wired, PLC-ready roll forming machines — designed, tested, and supported globally.
We also provide remote technical support, PLC diagnostics, and full wiring schematics for every machine we deliver.