Electrical control panel design basics are simple. Cost is always important, but so is an attractive appearance, simple operator controls and reliable operation. A simple panel design is less expensive to produce and easier to operate and maintain.
When you specify a control panel’s design requirements, it helps if you understand that control panel design is a process. Before you start the process you may think you know exactly what you want. After you start the process your ideas may change.
When you first put your panel design requirements on paper they seem unorganized. This is normal. No one gets everything right in one pass. Design is a process and it takes time to get it right.
Rewrite your requirements until they’re properly organized and clear. Understand what you want, write it down using clear language, then proceed with the actual hardware design.
1 • start physical
Don’t shortcut the design process and produce schematic drawings without producing physical layout drawings. Good control panel design includes physical and electrical requirements. Experienced control panel designers alternate between the physical and electrical until all potential problems have been solved.
Experienced control panel designers produce accurate physical layout drawings and schematic drawings. This minimizes problems and delivery delays due to unresolved physical layout problems discovered during production or testing.
Good control panel designers include National Electric Code (NEC) required clearance around power wiring and Underwriters Laboratories (UL) required clearance around heat producing devices.
- NEC requires bending radius clearance around incoming and outgoing power connections to insure the installing electrician has adequate room to make their power connections,
- UL requires manufacturer recommended clearance around heat producing devices (Programmable Logic Controllers, Variable Frequency Drives, etc.) to insure for adequate room for ventilation.
2 • coordinate wire sizes and component types
Good control panel designers size wires based on load current and circuit protection based on wire size. The correct wire size insures the circuit can deliver the required load current. The correct circuit protection insures high load current doesn’t allow wiring to overheat and start a fire.
Good control panel designers select components based on voltage and load current and component type based on function. The correct component size insures it can reliably handle the required voltage and load current. The correct component type insures it’ll function as desired.
3 • use the best control type
Experienced control panel designers always start with simple control components (Relays, Timers, etc.) When simple does’t get the job done, they’ll use something with more functionality like a programmable Smart Relay or a Programmable Logic Controller (PLC). These provide significantly more functionality, but they also require a computer and programming software and someone who knows how to use the software to program the desired functionality.
Some control panel designers automatically start with a Programmable Logic Controller (PLC). Sometimes a PLC is the way to go, but you should always use the simplest control type appropriate to the application.
4 • use the best operator device type
Experienced control panel designers always start with simple operator devices (Pushbuttons, Pilot Lights, Digital Panel Meters, etc.). For a stylish appearance they’ll add a Color Graphic door laminate. When simple does’t get the job done, they’ll use a color touch screen display as the Human Machine Interface (HMI). This provides significantly more functionality, but it also requires a computer and programming software and someone who knows how to use the software to program the desired functionality.
Some control panel designers automatically start with a Human Machine Interface (HMI). Sometimes an HMI is the way to go, but you should always use the simplest operator device type appropriate to the application.
5 • use the best in class products by category
Experienced control panel designers use the best in class products by product category. This is subjective based on product awareness. Experienced control panel designers are aware of the array of products available in a product category. This allows them to compare and use products that provide the best balance of price, form and function.
Some control panel designers try to use one manufacturer for all components in a panel. European companies tend to do this and some US companies do too. Sometimes there’s a reason why this makes sense, but generally it limits your ability to use best in class products by product category.