EMC Cubicles производства Siemens

Electromagnetic compatibility (EMC)

EMC measures are becoming more and more important both for individual devices and complete systems. The reasons are in particular:

• System processing speeds are becoming ever faster
• Systems are becoming more extensive
• Many different device types may be encountered in a single system
• Various power levels may be present in a single system
• More and more external interference sources

Definition of EMC

"Electromagnetic compatibility is the ability of an electrical system to function satisfactorily in its electromagnetic environment without influencing this environment, to which other systems may also belong, to more than a permissible degree."

To ensure the EMC of a system, it is necessary that its devices emit only limited interference and are at the same time immune as far as possible to external interference. In other words, the level of interference emitted by a device must lie below the interference threshold of any second device installed in the same location, taking into consideration the influence of the interference transmission path (keyword: "Interference immunity").

For such evaluations, the whole frequency range from 0 Hz to an upper limit frequency determined by the device concerned, which could well lie in the GHz range, must be taken into account. To be able to meet the overall requirements, it is imperative that the devices satisfy certain demands, and that they comply with the defined limit values regarding interference emission and interference immunity.

Design of an EMC cubicle

The 8MC/8MF EMC cubicle is available in the version:

• galvanized, with approx. 55 dB attenuation.

How does the PC cubicle differ from a system cubicle?

The following differences can be listed compared to a standard 8MC/8MF system cubicle:

• Paint finish only on the outer surfaces of doors and rear/side panels
• Conductive seals pre-mounted for doors and rear/side panels
• Additional standard base plate

The whole cubicle frame and all enclosure parts are galvanized, which serves to extend the shield attenuation measures to the cubicle installations.

The visible (exterior) areas of the cubicle enclosure are painted. Doors, roof panel, side panel and rear panel are provided with special RF seals and each screwed to the cubicle frame at several points. Special EMC cubicles can be supplied in all standard dimensions, but only up to a width of 900 mm and only with single-wing doors. The cubicle enclosure parts can also be supplied with ventilation slots and integrated RF seals.

The shield attenuation of the 8MC/8MF EMC cubicles is approx. 60 dB over a frequency range from 10 kHz to 1 GHz (corresponds to an attenuation factor of 1000). By comparison, standard 8MF cubicles provide a shield attenuation of up to 20 dB.