Fitting out electrical enclosures
Paul Metcalfe of Rittal looks at how to minimise time and costs when fitting out the interior of electrical panels and enclosures.
Switchgear manufacturers have a number of challenges when it comes to fitting out the interior of an enclosure. First, there are the high packing densities, and second the very short project times, which essentially means as many components as possible must be fitted as quickly as possible into the enclosure. No pressure there, then.
These components include power distribution systems, switchgear, automation components, clamps and so on, and of course once they’re in, they need to be wired up. Arranging them logically inside the enclosure is to some degree both an art and a science. The engineer needs to create an easy-to-follow solution for the end user, as well as pay attention to relevant standards, and of course follow the component manufacturers’ installation instructions.
And as we’ve indicated, the longer it takes to configure the interior, the greater the time and cost pressures on the electrical engineering company, particularly if these are multiplied across many projects. Not surprisingly, the design of the actual enclosure and the amount of space the installer has to play with has a major part to play in how quickly the interior can be
Rittal’s TS 8 enclosure has a central element, a frame section with a uniform 25-mm pitch pattern which adds to the flexibility of the space for electrical equipment and also reduces ‘wasted space’ to a minimum. Two other mounting levels can be used and, by using the external mounting level, the installer automatically has up to 15% more space at their disposal, compared with a single-level alternative.
The amount of available space can also be increased by using the gaps between the bayed enclosures. By inserting a mounting plate infill between two TS 8 bayed enclosures, installers can create a useful continuous mounting plate. Alternatively, this space could be useful for a cable duct. Installers can then add other components onto the mounting plate.
All these ideas can help increase the amount of space and solve the problem of packing densities in the enclosure.
Rapid installation has a number of benefits. Apart from the fact that a system can be completed more quickly for a client, fewer staff are also needed, which therefore lowers costs.
Many systems still require two people to install them (for example, to mount the side panel of the enclosure) so choosing an enclosure that only needs one installer has considerable business benefits. Again, the TS 8 is constructed so the side panel can first be suspended from the enclosure. It then remains in position without having to be held by a second person before it is screwed tight. Other assembly steps (for example, changing the door hinges from one side to the other) follow the same principle so there is no need for two installers. Meanwhile, the TS 8’s Flex-Block base, means there is no need for tools – panels can be simply clipped on. The entire base has been assembled in less than 60 seconds during installation workshops.
At a time when products and systems are becoming increasingly complex, configurators are an indispensable tool for helping customers quickly track down the right product for their needs. These online tools help users precisely determine the necessary parameters, quickly select the appropriate solution, and automatically compile technical data.
For example, Rittal’s TopTherm chiller configurator enables designers and technical buyers in to put together machinery and process cooling systems. It provides precise estimations of the required cooling output, rapid identification of the most suitable solution and automatic generation of all technical specifications.
We finish with a look at the number one priority for this, and any other electrical engineering installation, which is of course safety. It goes without saying that fault currents (short circuits) and enclosures which become ‘live’ both have the potential to cause serious harm. The earthing of metallic parts on electrical systems is prescribed virtually everywhere and applies to all electrical equipment and units. In low voltage switchgear, all the metal frame and enclosure parts at risk of stray voltage have to be earthed.
Many enclosure manufacturers require each panel to be earthed through earthing straps of copper wire connected to the frames, the side panels, the enclosure roof, any other panels as well as the door. Once fitted, the straps ensure there is an equalisation of potential and the enclosure components can be earthed via the protective conductor of the voltage supply. However, the straps have to be attached by hand during enclosure assembly, and should a strap be inadvertently forgotten, the finished switchgear will still be able to function despite the risks it poses in the event of a fault.
There is obvious sense in the industry moving towards built-in safety, avoiding the need necessarily having to earth each individual panel. In the TS 8, side panels, enclosure roof, rear panel and gland plates are automatically connected to the frame conductively, creating potential equalisation. The enclosure uses special claws or washers which press through the electrically non-conductive surface coating of the panels during assembly to achieve a reliable contact. The earthing strap then only needs to be attached to the enclosure door.
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