Enclosures - The basic enclosure - only the starting point

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Increasingly demanding applications have driven the innovation of new products to set new industry standards. The electrical control enclosure in today’s technological environment needs to address an array of different applications and when considering which enclosure is suitable for an application, the basic enclosure is now only the starting point says Sando Selchow of Rittal


Within manufacturing process environments electrical enclosures are often situated in close proximity to the actual products being produced. The mechanical components used in and around such process plants tend to accumulate deposits and the electrical enclosure is no exception, with particles possibly cultivating on enclosure surfaces, crevices and recesses. If this were a food, pharmaceutical or chemical plant a strict hygienic protocol would need to be adhered to in order to prevent contamination. Maintaining a hygienic working environment in this type of environment although of paramount importance is always a constant battle.
Rittal has recently introduced a new range of hygienic design enclosures to facilitate in this constant battle. The range has been specifically designed to prevent deposits cumulating on the enclosure surfaces, crevices and recesses to help eliminate any potential contaminants, which could negatively impact on customer production.

Incorporated into the design is a 30° angled, sloped overhanging roof preventing any liquids or solids collecting on the roof area. A larger than average gap to the top of the door, allows for easy cleaning and prevents any unwanted deposits from reaching the door seal. The door has outward pointed edges (approximately 135° compared with 90° folded standard enclosure doors) and a larger flat surface on the inside of the edge. Together with the flat silicone base seal, the door builds a perfect corner finish, free of gaps and contact areas preventing any unwanted deposits.

The enclosure has a protection category of IP66, which also includes the internal door hinges to create an all round gap free door. The new flat gap free silicone door seal is coloured blue, which is the industry standard colour for non-consumable products, and offers a high resistance to all process and cleaning liquids.

Various different mounting options are available. The enclosure can be mounted either with tubular mounting brackets with a smooth finish, or open frame plinths with a clearance height of 300mm, designed from tubular stainless steel. Both options allow easy cleaning access and minimise entrapment areas. Adjustable levelling feet, with internal sealed threads, make entrapment areas completely obsolete and new stainless steel cable glands stop any particles from attaching themselves within the glands or connections.

Electrical enclosures, which are used in hostile situations in the manufacturing process environment, are usually hosed down at the end of the day. Often high pressure cleaning equipment is used and the mechanical equipment or controls are included in this wash down. In this type of environment where the controls need to be protected against any form of water ingress it is recommended that a stainless steel sealed enclosure be used which meets the demanding standards of IP69K.
More stringent cleaning methods are required within food processing plants where strong high velocity hoses are directed at machinery and their controls to prevent harmful bacteria from harbouring. The temperature in a process plant within a poultry factory could be around 10ºC ambient when in use, but when the cleaning process takes place, refrigeration is turned off, which allows the temperature to rise to 20ºC. The water temperature for cleaning is often higher than 50ºC and can have a water pressure of 70 bar. If the enclosure to house the controls was only rated at IP56 or 66 the control enclosure could fill with water, as the water temperature is far higher than the enclosure and the water pressure is greater than the design standard of the gaskets.
The IP69K protection category certifies the enclosure to be water ingress proof when tested on a turntable. The German DIN 44050 standard originated from requirements found in the automotive industry where spray water and high pressure cleaning resistance was required.
The IP69K to DIN EN 40 050 part 9/5.93 lists the IP (International Protection) rating for road vehicles. The IP rating is described in a combination of the two numbers and an additional letter behind the last characteristic numeral. In this case this creates for example the IP69K, where the letter “K” provides further information. The letter “K” refers to a special case for road vehicles which describes the protection of electrical devices in road vehicles with regards to foreign bodies, dust and, in particular, with regard to the penetration of water. The use of the additional letter “K” is, however, no longer used exclusively in vehicular applications, but also in the food and beverage processing industries. As this test procedure differs considerably from the other IP-tests, enclosures with IP69K test certificates are currently the highest protection standard available against water ingress.

The IP69K to DIN40 050-9/5.93 lists the protection category test consisting of the following parameters: Water pressure up to 100 bar; 14-16 litres per minute flow rate; temperature up to 80°C; distance min 100 to max 150mm. Duration of the test calls for 4 directions and test jet time of 30 sec each at the angles of 0°, 30°, 60° and finally 90°. To achieve the 4 directional test, the test object is placed on a rotating turntable.

Protection class IP69K is therefore an important standard for enclosure systems used in the food industries. In addition to the water ingress properties, the food industry also requires hygienic standards on the surface properties. Standard 304-grade stainless steel achieves the required levels, but what about the gasket material? Special properties are required, such as a non-bacteria harbouring surface and a smooth transgression between the stainless steel parts and the gasket materials. The German Institute, “Frauenhofer-Institute IPA”, certified the highest standards in the food and hygiene sector for the Rittal IP69K enclosure range.

When products are used in factories and applications around the world, common safety standards are set to make sure all health and safety criteria are met. Enclosures are no exception; meeting the requirements of the EN60529 ingress protection and EN60439 low voltage control gear assemblies standards.

New markets have also given the enclosure manufacturer the ability to supply complete packages. There are a wide range of different climate control solutions available that range from addressing condensation issues to more severe heat problems, heaters for raising temperatures above freezing, louvers for normal convection, fans for forced convection along with air-to-air heat exchangers, to technically sophisticated cooling systems for the more hostile environment. Power distribution can also be a prerequisite in control panels and a busbar system that offers advantages in assembly and space saving is an advantage providing possible cost and time savings.

Rittal’s extensive range of climate control solutions feature two control options that allow functions such as door switch control, condensate management, master-slave set-up, and network connectivity, as well as a wealth of system information that can be accessed and evaluated. On three phase units, the systems accept both 400 V and 460 V +-10% connections from one single standard unit. The internal air circuit design of the roof-mounted units can open up more possibilities in drive cooling applications or targeted cooling.