DN Staff

April 7, 2003

5 Min Read
Shape Shifters

Just as the semiconductor industry continues shrinking integrated circuits to put more technology into a single package, enclosure designers are also striving to let system developers cram more devices into each box. At the same time, enclosure makers are responding to other trends by reducing electromagnetic interference and improving sealing for products that are used in harsh environments.

As with most other product categories, the desire to get more functionality into smaller packages is interleaved with other demands. Design engineers want flexibility, being able to alter an enclosure to fit varying demands, yet still provide electromagnetic shielding and keep costs as low as possible. "Companies want to use every cubic inch, but if they don't want fancy features, they don't want to be charged for them," says Jeffrey Seagle, general manager at Stahlin (Belding, MI, www.stahlin.com).

Stahlin is meeting that demand with its DiamondShield line, which makes it possible to stack enclosures to any size, adding different panels as needed. Noting the importance of appearance, Seagle explains that Stahlin makes its enclosures from fiberglass, which makes it simple to alter colors. Color schemes can address branding or designate safety areas by making a bright red or yellow package. And the fiberglass panels can be altered to provide EMI protection.

That's becoming increasingly important as more electronic controls sit closer together. Hoffman Enclosures (Anoka, MI, www.hoffmanonline.com) recently separated EMI enclosures out as a distinct product category. "Electromagnetic cabinet sales are up even though we're in a down economy. It's becoming recognized as an inexpensive way to ensure that you won't have electrical interference," says Betty Jackson, product manager at Hoffman.

The need for EMI protection is driven in large part by the push to squeeze more circuitry and devices into a small amount of space. As more devices operate in a small package, the amount of EMI they generate will often rise.

Package designers at Rittal Industrial Product Group (Springfield, OH, www.rittal-corp.com) are responding with modular designs that provide shielding. Rittal's TS-8 line leverages the modular techniques the company has employed for years, using the frame to provide strength for the structure. By putting peripherals and other devices on the side panels and fans on the roof, system designers can gain 30% more mounting space than a similarly-sized NEMA enclosure.

In addition, there's no need to do any cutting or drilling, which sometimes happens with a NEMA package. The new line also makes it simpler to expand a system. "The TS-8 is symmetrical, which lets you connect to the back, sides, top or bottom," says Mike Murphy, product manager at Rittal's Industrial Product Group.

Another upgrade came with the push to reduce emissions. Engineers added a technique that reduces the leaks that can occur at panel junctions. "We've improved continuity of electronic grounding, using metal fittings so the system is completely bonded on all surfaces," Murphy says.

Feature Rich

Enclosure manufacturers are also moving to supply more functionality, adding features such as cable handling and power distribution. As more servers, controllers, and operator stations are linked to networks and to other equipment, the need for enhanced cable handling is growing. Responding to this trend, APW Enclosure Products (Waukesha, WI, www.apw.com) has come up with two new lines. The IMNet is an open enclosure designed to handle cabling for networks, while the IMServ adds panels to provide the protection and noise reduction needed in the server environment. Both provide the versatility needed in today's global marketing environments, meeting both IEC and DIN specifications.

Leveraging the networking IMNet design provides benefits for servers. "There's a spot for cabling, which helps in cooling and makes things neater so you have more access to the boards and backplane," says Dave Hammer, marketing manager at APW Ltd. He added that removable panels give full 360 degrees access to the cable raceways.

On another front, U.S. companies are adding power distribution systems to enclosures. That's a plus for OEMs who don't want to design their own power system or contract with another supplier.

Power protection is a big part of one new offering. "We provide a modular bus bar system that connects directly to the low voltage switch gear and can be braced for short circuit rating up to 100,000A," says Troy Miesse, product manager at Rittal's Power Distribution Products group.

In its latest development, the Maxi PLS line, Rittal offers pre-configured bus bars with many connection options that make it possible for design engineers to create power buses without making time-consuming alterations to flat rectangular stock that must often be drilled or machined to the necessary size and shape. "This lets us go head to head with traditional wiring," Miesse says.

Streamlining Options

While there's an overall industry push to put more functions in a single package, that trend has implications in other areas. When servers and control stations do more tasks, there isn't any reason to put much computing power in control stations. In industrial applications, the control stations that sit in strategic locations often communicate with servers in real time. System integrators who want simple stations for harsh environments find it difficult to get an inexpensive yet rugged enclosure. "There aren't a lot of choices in a mill where you've got a lot of moisture or dirt and heat," says Dennis Clark, manufacturing manager at Panelmatic Cincinnati Inc. (Fairfield, OH, www.panelmatic.com).

Panelmatic is currently rolling out a Remote Operator Station after selling it to select customers over the past year. The stainless steel enclosure holds a monitor, NEMA 4 protected keyboard, and the CAT 5 fiber-optic or other connectors needed to link the operator station to the network and the unit it controls. Purge equipment is included for environments that require it.

Hoffman is also focusing on harsh environments, unveiling a stainless steel enclosure with a sloped top that sheds water. The Watershed line also employs sloped door flanges, along with easy-operation latches, which ensure that no water gets into the cabinet.

With enclosure manufacturers applying such creativity in designing "inside the box," design engineers have more flexibility in economically packing in features for their customers.

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