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New generations of LEDs

Thursday, 1 January 2015 PDF icon New generations of LEDs
We have already spoken about LED lighting and the advantages that this lighting support can provide for lighting fixtures suitable for use in areas with potentially explosive atmospheres. However, the technology in this field is moving so fast that we think is appropriate to analyze the developments. The only term LED is no longer sufficient to identify the wide range of products which has been developed with particular characteristics according to the use. In electronics, the LED (light emitting diode) is an optoelectronic device that exploits the characteristics of semiconductor materials to convert the electric current that passes through it into light. Although the first LEDs were developed in 1962, only in recent years the technological progress has made it possible to fully exploit the LED to replace the traditional light sources with a long series of advantages.

Prevent explosions of metal dusts: analysis of a real case

Monday, 1 December 2014 PDF icon Prevent explosion of metal dusts
An explosion is a very complex physical-chemical process, which responds to dynamics not always easy to completely predict. We all know the pure theory: it’s necessary the presence of fuel, combustion and ignition energy to trigger an explosion. It’s not always easy to foresee, however, how these components are combined and how they are simultaneously present in the course of a machining process. Therefore, a necessary condition to lower the risk level is a more comprehensive prevention action that takes into account the most critical possible factors. This article will analyze a technical incident really happened (source: documentation ASL 14 VCO of Piemonte Region) and will draw conclusions about what can be done to prevent a similar incident.

Aluminium in explosion-proof electrical protection

Saturday, 1 November 2014 PDF icon Aluminium in explosion-proof electrical protection
Aluminium is one of the materials most used worldwide for the construction of explosion-proof enclosures. The excellent features of corrosion resistance make this material universally recognized as the most valuable and versatile for most applications. In respect to the cast iron, aluminium has the advantage of being much lighter and, thus, facilitate both the assembly and the maintenance of the system. Furthermore, it has a excellent corrosion resistance without the need to be protected on the surface, as happens with the cast iron which must be galvanized and varnished protected. Furthermore, in respect to the stainless steels, it has lower cost. The mechanical properties of aluminium alloys castings are highly satisfactory for use in the field of explosion-proof electrical protection.

‘Ex de’ lighting fixtures and floodlights with LED technology

Wednesday, 1 October 2014 PDF icon Cortem LED lighting fixtures and floodlights
It’s appropriate to clarify some beliefs about LED lighting fixtures and, more specifically, about their use in the segment of environments with a risk of explosion and fire: as men progressed in a continuous research of new technologies through by the technique of breaking stones for tools and the creation of energy by exploiting the natural flow of the rivers, in the same way Cortem is pursuing this philosophy approaching new technologies and adapting them to specific projects of research and development without being fossilized in the past. The new series of LED lighting fixtures and floodlights designed by Cortem have nothing in common with lighting fixtures and floodlights for discharge lamps. The old "enclosures" are not suitable to be used as a support for LED and do not lend themselves to dissipate the temperature generated, compromising the proper functioning and durability. Unfortunately, the "adaptation" and the transformation of old Ex lighting fixtures to new LED lighting fixtures are very widespread practices in the market. This leads to poor performance and limited benefits in terms of energy and cost savings for the end user. The use of appropriate LED lighting fixtures allows to obtain numerous advantages.

Further electrical dimensional parameters for "Panel boards"

Monday, 1 September 2014 PDF icon Further electrical dimensional parameters for Ex Panel Board
In this fourth and final part, we’ll explain the other parameters for the electrical sizing of Panel boards addressed to systems with the presence of danger of explosion, such as: choice of sectioning and interruption devices; the filiation / coordination; the tripping curves; the differential protection unbalance current (earth leakage); the dissipated power; the preheating. The correct choice of sectioning and interruption devices is the first that the designer must perform properly because it affects the electrical sizing, both the main circuit breaker and the departures.

EWL series LED lighting fixtures and floodlights exempt from photobiological risk

Monday, 1 September 2014 PDF icon EWL series exempt from photobiological risk
Cortem Group, always committed to technological innovation and safety of people and environment, submitted the EWL series LED lighting fixtures and floodlights to the test for the photobiological risk, as provided by IEC 62471, EN 62471 and CEI EN 62471 standards currently in force, and by the Legislative Decree N° 81 of April, 9th 2008 which introduced the risk assessment. These standards, as well as providing guidance for the photobiological safety evaluation, define the exposure limits (EL), the measurement techniques and the classification scheme for the evaluation and control of photobiological risks. The IEC 62471 standard contains several construction requirements related to the ANSI/IESNA RP-27.2 standard which is valid in North America. From the test reports, resulted that EWL series, both in the version without optics, with standard beam of 120°, and in the versions with optics concentrating the light beam, are fully compliant with the requirements of the "Exempt Group”.

The dimensioning of electrical conductors - Part three

Tuesday, 1 July 2014 PDF icon The dimensioning of electrical conductors for use in panel boards Part three
In this third part, we want to speak about how important is the correct sizing of the electrical conductors to be used as "wiring" inside the distribution panels which will be installed in explosion proof areas. So as the electrical conductors are properly sized, you need to analyze also the sizes and the characteristics of the organs responsible for their protection, as well as the protection of the underlying loads. Beyond the capacity of current conductors and the operating temperature, it’s essential that they are also sized according to pass-through specific energy, in order to avoid that the overheating, generated during the working or during the event of overcurrent due to a malfunction caused by short circuits, may be the cause of the increasing of enclosure’ surface temperature and, consequently, the automatic triggering of explosion of the outer atmosphere which, at that time, may be saturated with gas.

The marking of REV, REVD series cable glands using adhesive transparent labels

Tuesday, 1 July 2014
During the design of the new range of REV and REVD series cable glands in different materials (nickel plated brass, galvanized steel and stainless steel), we wanted to introduce a type of standard marking that would allow us to improve a precise identification of the product by the installer: the type of raw material used for the production, the exact measurement of the component, the type of thread as well as of course the certification data. Our target was improving the quality of marking always keeping in mind the compliance with the applicable regulations. The technical Standard relevant to cable glands (EN 50262) provides the sticker as a possible form of marking. We have chosen it as the most appropriate solution to report clearly and easily readable all the necessary information.

Dimensional criteria for the design of enclosures - Part two

Sunday, 1 June 2014 PDF icon Dimensional criteria for junction boxes - Part two
In this second part, we intend to describe the criteria for the mechanical dimensioning of enclosures addressed to potentially explosive atmospheres. First of all, it’s important to have the sizing parameters that must be provided by customer at the time of size request which are the basis for continuing the technical analysis. These parameters can be summarized as follows: Method of protection; Temperature Class; Ambient temperature; Description of the composition of the Panel Board and the electrical characteristics; Dimensioning of pre heater of the enclosure.

Dimensional criteria for the design of enclosures - Part one

Thursday, 1 May 2014
Many customers advise us the need to have a dimensional criteria for enclosures used as distribution panels, motor starters, control, signaling and marshalling boxes. Since this is a topic that covers many different aspects of dimensional character/construction, with this first part of the topic we intend to highlight the variables inherent to the proper sizing of enclosures suitable for installation in hazardous areas, from the mechanical and electrical point of view.

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