More with less, fewer, and smaller

The footprint of control equipment—the number of devices, physical size, and energy consumption—is getting smaller. Three companies offer observations on where technologies are headed in the server room and individual control cabinet.


New devices offer higher density in a control cabinet. Courtesy: Phoenix ContactWhile the economic lows of 2009 and the recession that followed are behind us, that period brought about a number of changes that continue within the industrial sector. Most prevalent of them, of course, were the impacts on the larger workforce. Everyone, including plant operators, maintenance people, equipment designers and OEMs, system integrators, and panel shops is doing more with less. One way in which that has been manifest has been a re-evaluation of the control cabinet designs and looking at ways to cut overhead from the cabinet itself.

Chief among these ideas was cutting the size of the actual cabinet. Simply put, smaller cabinets equate to smaller costs. However, shrinking the size of the panel means engineers must first figure out a way to shrink the components on the panel. Luckily for engineers today, there are more high-density products on the market than ever before, making the task of shrinking the cabinet significantly easier than it would have been even 10 years ago.

To help explain, let’s look at the foundational components within nearly every control panel: power supplies, relays, and terminal blocks. While each technology is fundamentally basic, great strides have been made by a number of manufacturers to allow these components to do more with less, to borrow a phrase offered earlier, with “less” referring to size.

Let’s start with the heart of the control cabinet: the panel power supply. Power supply technology has grown by leaps and bounds in the past 10 years. Today, a variety of manufacturers offer power supplies with a list of offerings, including current boost, remote alarm features, and circuit breaker tripping technology. The most amazing part of all of this is that these features are housed in power supplies that consume an ever-shrinking footprint. For example, 10 years ago, leading power supply manufacturers such as Phoenix Contact, Sola, and Puls offered 10 A, DIN rail-mountable power supplies that were about 160 mm wide. Today, these manufacturers offer 10 A power supplies with even more features in a design that takes up only 90 mm of DIN rail space. That’s a space saving of nearly 50%.

Likewise, relays have gotten much smaller. Terminal block–style relays have been on the market since the late 1990s. However, the installed base for their much wider predecessor, the “ice-cube” relay, remains very large. The leading benefit of terminal block relays is their size. At only 6 mm wide, they consume a fraction of the space taken up by ice-cube relays. Of course, they are limited in most cases to 6 A, so direct replacement will not be possible in every situation. However, since ice-cube relays used in control cabinets use about 25 mm each, it’s easy to see how much room can be opened up by switching to terminal block relays, which are only a quarter of that width.

Terminal blocks are the foundation of every control panel, and even a product as basic as that can do more with less. Over the years, simple changes in the construction of terminal blocks from most manufacturers have resulted in vast improvements. For example, higher-quality metals allow smaller terminal blocks to carry more current so the overall footprint of the terminal block decreases. Given the number of terminal blocks in an average control cabinet, saving a few millimeters on each quickly adds up as the number is multiplied.

Additionally, leading manufacturers, including Weidmuller, Wago, and Phoenix Contact, offer terminal blocks capable of landing multiple wires. For example, Phoenix Contact offers one product line that allows users to land two wires on each side of the terminal block such that two separate signals can be passed. This essentially gives users the ability to cut in half the number of terminal blocks they need. Again, this directly leads to a significant reduction in the number of components and, consequently, the space needed in the cabinet.

Engineers looking to reduce the overall cabinet footprint have more options than ever before. In doing so, they simply need to look at the core components used in nearly every control cabinet: power supplies, relays, and terminal blocks. In most cases, upgrading to current technology can lead to a reduction of 50% over equivalent components used just a decade ago. Individually, much is to be gained by upgrading each of these components; however, users looking to make a huge impact on their bottom line, and potentially cut the overall cabinet size in half, should seriously consider upgrading all three of these component types.

Jeremy Valentine is interface product marketing manager for Phoenix Contact, USA.

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Jonas , , 11/08/13 03:55 AM:

Personally I believe another important way to reducing cabinet size and footprint is to use fieldbus technology for sensors and actuators instead of 4-20 mA and on/off signals. By using fieldbus, you can put as many as 16 devices on a single pair of wire, taking the place of on average 3 signals per device (48 signal wires replaced by one pair of wires). Perhaps only 10 devices will initially be installed per fieldbus, but it is still a dramatic reduction in the number of cable pairs, terminal blocks, and most importantly I/O cards that results in less cabinets and footprint. Moreover, since all signals are marshaled in software, marshalling cross-wiring is eliminated. They call it “virtual marshalling”:

By using PROFIBUS-DP for motor controls such as variable speed drives (VSD), motor starters, and MCC, the need for relays and AC signals in the cabinets can also be reduced. This is over and above massive cable and I/O card savings.

Combining FOUNDATION fieldbus for process control and PROFIBUS-DP for motor controls is another way to significantly reduce the number of components and consequently, the space needed in the cabinet.

Using real-time digital communication networks all the way to the transmitters and valves also enables more effective intelligent device management (IDM) software part of the asset management system for device diagnostics, calibration trim, and configuration/setup. This enables more effective planning of daily maintenance and scheduling of turnarounds. Learn more: