Rolla IP42 Grilles
In most cases, switchgear device ratings are based on tests in open air i.e. they are not enclosed and should be considered nominal ratings. It is up to the final assembly manufacturer to provide verification for this.
All electrical equipment gives off heat especially when used near it’s maximum rating and there are two ways of managing this:-
- Ventilate according to manufacturers guidelines
- Derate according to tests
In the UK many end users prefer to specify sealed enclosures to IP54 which will provide protection from contamination and reduce disruption caused by shutdowns for maintenance or inspection. But sealing a board up to this level also means all the elements within it must be derated, usually by at least a frame size (often more). This has a huge implication for the initial purchase cost and maybe also the size of the board.
Another reason end users prefer sealed boards is safety of personnel. If there are no gaps in the enclosure this reduces the chance of someone poking something in with catastrophic results. Even louvres, mesh & ventilation grilles can be considered a hazard if the board is accessible.
Rolla have supplied boards with various levels of ventilation at different IP ratings over the years.
Many commercially available grilles have drawbacks as they are not designed for use on switchgear, for example they may be too heavy, not sufficiently sealed or made from inappropriate materials.
With this in mind we at Rolla have developed and tested our own IP42 rated grille which is made from high strength polycarbonate, is truly non-vision and has excellent airflow performance. The IPx2 rating means it is resistant to water ingress dripping vertically and up to 15 degrees from the vertical.
A 1mm test probe cannot enter (IP4x), but air can pass relatively freely. Non-vision means there is no direct path even for light to enter. It has approximately 60% free air equivalent (much better than any louvre, mesh or slot based system).
Multiple grilles can be fitted as required.
For those projects where ventilation is standard (or can be permitted) this ensures the most cost effective and reliable way of achieving the maximum rating from enclosed devices without the use of forced ventilation. Rolla have tested sections up to 6300A continuous rating (including an Air Circuit Breaker) naturally ventilated i.e. without the use of fans therefore providing the highest level of reliability.
The standard for enclosed switchgear (BS EN 61439-2:2011) permits manufacturers to use calculations to verify compliance but only under strict conditions and not above 1600A. Rolla have been carrying out temperature rise tests for many years, have a test laboratory and can therefore demonstrate that our switchboards comply with the standard and are fit for purpose, with or without ventilation.