In brief
A control cabinet is an enclosure that houses and protects the electrical equipment of a machine or plant, such as controllers, drives and protective devices.
Contents
What is Control cabinet?
In a control cabinet, components such as the incoming supply, circuit breakers, contactors, frequency inverters, controllers, power supplies and terminal blocks are grouped on mounting plates and DIN rails. The enclosure protects them against contact, dust, moisture and mechanical damage. The IEC 61439 series of standards applies to low-voltage switchgear and controlgear assemblies, and IEC 60204-1 to the electrical equipment of machines. National regulations and standards on electrical safety must also be observed during construction and modification.
A distinction is made between wall-mounted enclosures, floor-standing cabinets, baying systems, console enclosures and terminal boxes, made of sheet steel, stainless steel or plastic. Key parameters are dimensions, degree of protection, material, load capacity and the climate control concept. Filter fans, heat exchangers or cooling units remove heat, while heaters and thermostats counter condensation. Cable glands and entry plates bring cables in without reducing the degree of protection. Inside, cable ducts, DIN rails and clear labelling of the equipment ensure a good overview.
In maintenance, control cabinets mainly involve wear of fans, filter mats, cooling units and door seals, as well as ageing components inside. Up-to-date wiring diagram documentation is a prerequisite for rapid fault-finding and correct identification of spare parts. Thermographic images help to detect overloaded terminal points or protective devices at an early stage.
In practice: maintenance and procurement
Keep the bills of materials and wiring diagrams of every cabinet up to date and mark critical components. Filter mats, fans and cooling unit accessories are among the plannable wear parts whose replacement interval should be recorded in the maintenance plan.
Synonyms and abbreviations: electrical cabinet · switch cabinet · control panel · electrical enclosure · switchgear assembly
Frequently asked questions
What goes into a control cabinet?
Typical contents are the incoming supply with main switch, protection by circuit breakers or motor protection circuit breakers, contactors, frequency inverters, a controller with input and output modules, power supplies, relays, terminal blocks for connection to the field and cable ducts. Components for climate control and lighting are added. The exact content is defined by the wiring diagram and the bill of materials.
What degree of protection does a control cabinet need?
The degree of protection depends on the environment. In clean indoor areas, lower degrees of protection are often sufficient; in dusty or damp environments, for example in the food or paper industry, higher degrees of protection against dust and water jets are required. Note that fans, cable entries and cut-outs can reduce the degree of protection of the overall system.
Why does a control cabinet need to be cooled?
Electronic components such as frequency inverters and power supplies generate heat losses. If the internal temperature rises above permissible values, components age faster or shut down. Filter fans, heat exchangers or cooling units remove the heat. Dirty filter mats are a common cause of overheating and should be replaced regularly.