How to Design a Control Panel Layout for Roll Forming Machines (Industrial Cabinet Engineering Guide)

How to Design a Control Panel Layout

Industrial Cabinet Engineering for Roll Forming & Coil Processing Machines

Control panel layout design is where electrical reliability is either engineered properly — or compromised before the machine even runs.

In roll forming and coil processing equipment, poor layout causes:

• VFD overheating

• PLC instability

• Encoder noise

• Nuisance breaker trips

• Difficult troubleshooting

• Reduced panel SCCR

• Maintenance access problems

A properly designed layout ensures:

• Safe power distribution

• Clean control signal routing

• Effective thermal management

• Proper short-circuit withstand

• Easy servicing and expansion

This guide explains how to design a control cabinet layout correctly from first principles.

1) Start With Functional Zoning (The Foundation of Good Layout)

Before placing components, define electrical zones.

A professional industrial cabinet is divided into:

1. Incoming Power Zone

2. Power Distribution Zone

3. Drive Zone (VFD section)

4. Control & Automation Zone

5. Safety Circuit Zone

6. Terminal & Field Connection Zone

7. Grounding / Earth Bar Zone

Never mix these randomly.

2) Standard Vertical Layout Philosophy

Most reliable layouts follow this vertical logic:

• Top: Incoming power
• Upper-middle: Main protection & busbars
• Center: Drives & heavy power devices
• Lower-middle: Control power & PLC
• Bottom: Terminal blocks & cable exit

This helps:

• Shortest path for high-current conductors

• Heat rising away from PLC

• Service clarity

3) Incoming Power Section Placement

Word-Based Power Path

Supply → Main Isolator → MCCB → Busbar System

Design rules:

• Place near cable entry point

• Keep short cable runs from gland to breaker

• Separate from control wiring

• Ensure mechanical support for heavy conductors

Avoid routing motor cables across PLC section.

4) Busbar Placement

Busbars distribute power from main MCCB.

Design principles:

• Horizontal orientation preferred for branch take-offs

• Adequate spacing between phases

• Clear mechanical supports

• Accessible for inspection

Busbars should not be hidden behind control wiring.

5) VFD Placement (Drive Section)

Drives are major heat generators.

Placement rules:

• Allow airflow between drives

• Follow manufacturer minimum spacing

• Keep away from PLC and low-voltage electronics

• Keep motor cable exits close to drive

Word-Based Flow

Busbar → Branch Breaker → VFD → Motor Cable → Gland Plate

Motor cables must exit near bottom to avoid crossing control cables.

6) Control Power Section

Control power typically includes:

• Control transformer or SMPS

• 24VDC PSU

• Fuse blocks

• Relay interface

Placement:

• Below drive section

• Away from busbars

• Separate trunking for 24V wiring

Keep “clean 24V” and “solenoid 24V” separate.

7) PLC & Automation Zone

Core components:

• PLC CPU

• Digital input/output modules

• Analog modules

• Communication modules

• Network switches

Design rules:

• Install at ergonomic height

• Keep wiring neat and horizontal

• Separate from power trunking

• Shielded cable terminations close to entry

PLC area should be the cleanest zone in cabinet.

8) Safety Circuit Layout

Safety devices include:

• Safety relay

• E-stop loop terminals

• Guard switches

• Light curtain interfaces

Design principles:

• Physically separate from standard I/O

• Clearly labeled

• Redundant paths where required

• Easy inspection

Safety wiring should never be mixed casually with standard control wiring.

9) Terminal Block Arrangement

Terminal blocks should be grouped logically:

• Motor terminals

• Sensor terminals

• Safety terminals

• Power terminals

• Spare terminals

Keep them:

• Clearly labeled

• Sequentially numbered

• Separated by function

Avoid mixing 400V and 24V terminals side-by-side.

10) Cable Routing Strategy

Inside cabinet, use:

• Separate trunking for power and control

• Minimum crossing points

• 90° crossing only where unavoidable

Never route encoder cables parallel to motor cables.

Field wiring entry:

• Power cables one side

• Control cables opposite side

This reduces EMC interference.

11) Thermal Management Design

Heat sources:

• VFDs

• Transformers

• Contactors

• Power supplies

Design must include:

• Airflow path (bottom to top)

• Filtered fans or AC unit

• Clearance above drives

• No blocking of vent grills

Overcrowded layouts lead to overheating and premature failure.

12) Grounding Layout

Single main earth bar.

All protective earth conductors return to:

PE → Earth Bar → Incoming PE

Motor cable shields must terminate properly.

Avoid:

• Multiple ground points creating loops

• Long PE return paths

Grounding must be physically accessible.

13) Serviceability & Maintenance Design

Good layout considers:

• Tool access

• Clearance in front of devices

• Easy replacement of drives

• Space for adding modules

Poor design increases downtime.

14) Expansion Planning

Leave:

• Spare breaker space

• Spare PLC I/O space

• Extra terminal blocks

• Additional trunking capacity

Many roll forming factories add punch units or extra drives later.

Plan now, not later.

15) Common Layout Mistakes in Roll Forming Panels

1. Drives directly above PLC (heat damage)

2. Power and control wiring mixed

3. No cable segregation

4. No room for airflow

5. Terminal blocks too crowded

6. Grounding bar inaccessible

7. No spare space for upgrades

8. Excessively long cable runs inside cabinet

Layout errors often appear as “random electrical faults.”

16) Example Layout Logic (Word-Based Diagram)

Top Section:
MAIN ISOLATOR → MCCB → BUSBAR

Middle Upper:
Branch Breakers → VFDs

Middle Lower:
Control Transformer → 24V PSU → Safety Relay

Lower Section:
PLC → I/O Modules → Terminal Blocks

Bottom:
Field Cable Exit

Earth Bar:
Side-mounted near cable entry

This structure supports safety, cooling, and serviceability.

17) Export Considerations

When exporting machines:

• Voltage differences may require transformer space

• Different breaker sizes may require larger clearance

• Higher fault level markets require stronger busbar spacing

• Cooling capacity may need adjustment for hotter climates

Design for global adaptability where possible.

18) Buyer Strategy (30%)

Before accepting a control cabinet design, ask:

1. Is there functional zoning?

2. Are power and control circuits separated?

3. Is thermal load calculated?

4. Are VFD spacing requirements met?

5. Is there room for expansion?

6. Are terminal blocks logically arranged?

7. Is grounding centralized?

8. Are drawings available for layout?

Red flag:

“All components fit — that’s enough.”

Fitting physically is not engineering.

6 Frequently Asked Questions

1) What is the most important layout rule?

Separate power and control circuits physically and electrically.

2) Why are VFDs placed away from PLC?

To reduce heat exposure and electrical noise.

3) How much spare space should be left?

Enough for at least one future drive or expansion module.

4) Can poor layout cause VFD faults?

Yes. Heat and EMI can cause instability.

5) Does layout affect short-circuit safety?

Yes. Busbar spacing and mechanical support influence fault withstand.

6) What is the biggest layout mistake in roll forming cabinets?

Designing without considering heat, EMI, and future expansion.

Final Engineering Summary

Control panel layout design for roll forming machines must integrate:

• Functional zoning

• Proper power distribution

• Thermal management

• EMC separation

• Safe grounding

• Serviceability

• Expansion capacity

A well-designed cabinet layout is not cosmetic — it is foundational to long-term production reliability.