Getting into Enclosures

Housing for control and automation devices and networks is evolving right along with the devices they contain, so it's even more important now to choose the appropriate enclosure for your application. Here's how.

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EnclosuresBy Jim Montague, Executive Editor

Many people in control and automation field have a pretty snooty attitude about enclosures. Oh sure, they just sit there, but it would probably be smart to be less dismissive about hardware that protects so many critical components and, consequently, covers so many engineers' metaphorical rear ends.

Of course, it may have seemed like enclosures were on their way to Commodity Land recently. More control devices and their networks are over-molded and encapsulated to the point that they claim to no longer need enclosures. Flash memory that doesn't need a protected housing is replacing hard-drives that traditionally require enclosures. And more transceivers, PLCs and similar components are using twisted-pair fieldbuses, Ethernet and even wireless, so less cabling, cabinets and other support hardware is needed.

However, as computing power continues to shrink and be distributed further into the field, many process control users are finding they need more, smaller and more specialized housing for protection against overheating, electromagnetic interference (EMF), reduction of hazardous substance (RoHS) compliance and to meet other multiplying needs. So, far from becoming passe, enclosures probably are diversifying more now than at any point in their collective history. For example, to allow increased customization of its plastic and aluminum enclosures, Fibox recently added a computer-aided manufacturing (CAM) and computer numerical control (CNC) machining system for milling, engraving, cutting and embossing. This enables faster turnaround on modifications, including threaded and unthreaded holes, and panel, door, side and window cutouts. This new CAM machining system can customize any of Fibox's more than 750 standard enclosures. Also, a graphics converter built into the new CAM system's software makes it easy to accept files from computer-aided design (CAD) programs and convert them to the proper machining instructions.

     FIGURE 1: SUDS AND SALT
  Pro Car Wash systems
 

ProEquipment Co. uses a variety of Hoffman's Concept Enclosures to protect the computers, starters, contact relays, and other controls in its Pro Car Wash systems.

Out and About
No longer confined to the plant floor, some enclosures are being successfully deployed in unconventional settings. For example, to prevent unexpected equipment failures and downtime, Pro Equipment Co. in Benton, Ky., uses Concept enclosures from Hoffman to protect its Pro Car Wash systems' computers, PLCs, starters, contact relays and other controls in wet and dry settings (See Figure 1). The OEM uses more than 2,000 types of cabinets in the automatic and self-serve car washes its sells worldwide. Pro Equipment's PLC controls every automatic wash function.

"In one equipment room, a water line burst and sprayed water directly on the Concept box housing the PLC," says Randy Travis, Pro Equipment's owner and president. "We had one foot of standing water in the room, but our PLC was safe, dry and protected. Though car washes store many spare parts, it's too expensive to keep a $12,000 backup computer, so the enclosure is critical to car wash operations."

In addition, Austrian Federal Railways uses Rittal's enclosures and racks in its multi-system Siemens Eurosprinter Rh1216 050-5 locomotive (See Figure 2), which broke the 51-year-old record for world's fastest rail vehicle by traveling at 222 mph (357 km/h) twice in one hour on Sept. 2 on German Railways' (DB) high-speed line between Ingolstadt and Nuremberg. Eurosprinter incorporates Rittal's PS 4000 enclosure system with 16 mounting plates and two large swing frames. The PS 4000 with EMC forms the backbone of the electronic enclosure, which is protected against intense vibration and high-frequency electromagnetic interference. Components for distributing 3,000 V DC are accommodated in Rittal's 3 kV racks.

FIGURE 2: HIGH-SPEED RAIL     
Siemens Eurosprinter  

Austrian Railways' record-breaking, multi-system Siemens Eurosprinter Rh 1216 050-5 locomotive uses Rittal's PS 4000 enclosure with EMC equipment forms and 3 kV racks.

 

"Railway operators and vehicle manufacturers place high demands on the quality of the assemblies and components installed," says Hermann Becker, Rittal Rail Traffic Systems account manager. "Nowadays, electrically powered locomotives' control technology contains a huge number of electronic and electromechanical components, which have to be safely accommodated in enclosures and on frameworks throughout the locomotive's entire service life. Special products are used that are adapted to the dynamic requirements."

Novelty applications aside, enclosure diversification means it's more important than ever for end users, system integrators and others specifying professionals to be thoroughly aware of their applications' changing characters and what level of protection they truly need. "Specifying enclosures to protect electrical and electronic components has become increasingly complicated. In most applications, it's no longer enough to order a simple box to house your equipment. Many factors, including application demands, hardware, performance and operating environment can greatly affect the operational reliability and life of your equipment," says Emily Orvik, Hoffman's communications manager. "Determining the right enclosure for your application is made easier by seeking suppliers with the most choices, application experience and technical resources. No matter what brand you select, the following tips and considerations will make getting the right enclosure easier."

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