CASES & ENCLOSURES FEATURE
With safety and security essential for installers and users of electrical switchgear, Rittal has introduced the TS 8 baying system
Ensuring electrical safety
potential equalisation between all the metallic parts of an enclosure. The earthing of metallic parts on electrical systems for safety reasons is therefore needed, and this applies to all electrical equipment and units. After all, if an enclosure, for example, was to become live, it has the potential to cause serious harm. In low voltage switchgear, all the metal frame and enclosure parts endangered by stray voltage have to be earthed. Earthing straps are therefore usually
provided, which can safely contact moving parts such as doors to the enclosure. The earthing straps typically also have to be connected to the frames, the side panels, the enclosure roof and any other panels. Once all the earthing straps have
been correctly fitted, there is an equalisation of potential, and all the enclosure components can be earthed via the protective conductor of the voltage supply. However, as they have to be attached by hand there is a danger the strap could be forgotten. To help limit this risk, Rittal has
I
ssues such as fault currents can cause injury to personnel or property, so standards and regulations must be followed. These, however, also cover the
The TS 8 bayed enclosure system from Rittal
developed an effective solution with the TS 8 bayed enclosure system. During the assembly phase, the side panels, enclosure roof, rear panel and gland plates are automatically connected to the frame conductively. This means potential equalisation can be achieved without necessarily having to connect these parts
with earthing straps (although the final decision as to whether to leave earthing strips out completely is up to the user). The solution is implemented using
special claws or washers which press through the electrically non-conductive surface coating of the panels during assembly, to achieve a reliable contact. It means that all the flat panels are electrically connected to the frame so that, in many applications, earthing straps are no longer needed. Instead, the earthing strap only needs to be attached to the enclosure door. The contact resistance between the panels and the enclosure frame is less than 0.1Ω, the value demanded by the DIN EN 62208 empty enclosures standard. Not only does the automatic potential equalisation reduce the amount of material needed and enable easier assembly, but it is also easier to disassemble and re-assemble individual panels because the earthing straps do not have to be removed and re-attached each time. Users must consider whether the
design measure of automatic potential compensation is sufficient or whether separate earthing straps are needed to meet the technical safety requirements.
Rittal T: 01709 704000
www.rittal.co.uk
IT INFRASTRUCTURE
SOFTWARE & SERVICES
www.rittal.co.uk
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