Bench Talk

As more and more technology is deployed within industrial and commercial environments, there is an increasing need to safely and securely house all the various components that make up today’s control systems. For many applications, the challenges include balancing the needs of securing crucial electronic systems, bringing order to complex systems and their associated wiring, and protecting equipment from environmental conditions such as moisture and dust.

Planning the design of a control cabinet according to equipment functions not only makes sense from the perspectives of accessibility, maintenance, and flow, but it also helps separate any equipment that might be susceptible to interference from other components. Sturdy DIN-rail control cabinets have long been used to meet the essential requirements of production systems, accommodating everything from power, connectivity, and control. Safe and sound within a control cabinet, all the parts that make up a production control system can be laid out according to their individual functions.

An example of a functional design approach can be found in the Build with Confidence brochure from Phoenix Contact. Providing the interconnectivity with the plant being controlled is that of the connectivity section. Tasked with making a reliable connection to cabling of all sizes, from heavy-duty electrical to small signal data switching, this section will also contain relays and isolation devices in addition to a variety of terminal blocks and connectors appropriate to the application. Emphasis needs to be placed on how each connection is made—whether by screw, crimp, or insulation displacement—and the quality of the connectors because the reliability and operation of the control system is underpinned by the connections to it.

Safety is another key function located within the cabinet, providing further aspects of isolation, particularly that of intrinsically safe circuits. A mix of safety relays as well as configurable and distributed safety controllers will be housed within this area. Tasked with meeting occupational safety regulations such as OSHA, Phoenix Contact’s safety controllers are configured through a simple graphical software interface.

The next functional section is that of the core network components that are responsible for the communication, switching, and protocol conversion. This includes Ethernet/IP and process field net (PROFINET) solutions that are commonly used as the industrial network protocol of choice and also comprise the fabric of the control solution. Located above these are the networking and remote connectivity units that facilitate connectivity to the broader wired and wireless infrastructure. Typical components here include routers, firewalls, and 802.11-compliant wireless access points.

Providing the essential control function is a variety of industrial PCs, programmable logic controllers (PLCs), and human-machine interface (HMI) controllers. Playing the pivotal role of receiving, processing and provisioning data, and using industrial network protocols such as PROFINET, EtherCAT, Modbus, and Ethernet/IP, these devices form the logical heart of the overall control solution.

Essential to keeping everything running is that of the power reliability functional units. Incorporating the power supply units, surge, and other circuit protection devices, the management of power distribution, metering, and monitoring should also be allocated space in this area.

A final point to consider is how the cabinet’s various components and cables are identified. The use of equipment ID labels, cable markers, and other automated and hand tools not only helps speed the time spent configuring and commissioning a control system (making the shop floor more productive), buts also aids the ongoing maintenance of the installation. Attempting to fault-find in a cabinet without clear system diagrams and cable identification can result in considerable down-time and lost production.

Adopting a functional layout approach to the design of your control cabinet installations will ensure they are built with confidence.