Is it hot in here or is it just me?

Next-generation networks are hot in more ways than one. As manufacturers produce smaller, more powerful devices that take up less space — but have more features, run more applications and help public network operators offer more services — a sometimes forgotten byproduct can be heat problems.

“Cooling now is as important as power,” says James Hall, telecom market manager for Liebert. “Three years ago it was a secondary thought. Now, with facilities that have at least 300 W per square foot, if cooling is not working in three to five minutes, all loads will fail to operate and shut down.”

In short, power supply and thermal control can no longer be taken for granted in today's public networks, especially if operators are packing more equipment into less space (Figure 1).

“The big issue today for most carriers is a reduction of floor space,” says Iain Stevenson, research director of next-generation networks for Ovum, a telecom consultancy based in London. “The equipment in place now, including next generation, is more efficient than what it replaces. Things, in theory, should get better. But with more density and more watts per square foot, heat is an issue that one has to face up to.”

Those in the industry say power demands on the access side have grown from about a half a watt per subscriber to seven or more watts per subscriber depending on the technology. To meet this demand, power density increases, and public network operators must be aware of new requirements or risk unexpected network failures.

“For co-location, data centers, central offices or hubs, you have to provide power density or plan for power density in the range of 150 W per square foot,” says Rick Marcotte, vice president and general manager of Invensys Energy Systems. “And that's getting into the range of what you can effectively move in terms of hot air out of a facility.”

“Efficiency and power density go together. More people are sensitized to this issue today, and you have to look at the amount of input that gets translated to output,” he says. “If that is low, the more heat is thrown off. So we're spending a lot of time on efficiency of equipment.”

Rajesh Nair, founder and president of Degree Controls, says his company sees the same thing happen over and over with new products. “People underestimate the problem related to thermal issues. The biggest problem is thermal density,” Nair says. “The marketing department wants more features in a smaller box. The downside is that heat density goes up, and we are reaching the limits of physics (Figure 2). Some products we are working on are way out there with close to 8000 W — it's enough to cook with in a small box.”

The development steps, he says, are to work on ways to take heat out of the device and the product, move it into the room and then take the heat out of a room.

But that isn't always easy to do, either. “The problem isn't in heat removal,” says Kevin Dunlap, American Power Conversion's senior product manager of the network air precision air conditioning group.

“Refrigeration hasn't changed in the last 90 years,” he says. “It is basically the same process, but the problem is in distributing the air. You capture the heat load and reject it. But when you are increasing the watts per square foot, how do you distribute air to the load when it is that dense? Right now, the solution is in the design phase. You have to design for this and get the right airflow to where you have the heat. It is an engineered solution.”

Bob Bauer, president of Liebert Americas, agrees. “Unless some revolutionary technology hits the street, the way we like to think is that if a certain amount of energy is in the building, then a certain amount has to get out. If power density goes up, heat loads go up. It's heat, and that makes heat removal important.”

Who turned out the lights?

Power outages are another interesting factor operators have to deal with. While COs, data centers and critical base stations will have some form of uninterruptible power supply (UPS), generator or battery backup system, those systems are not always hooked up to the air conditioning.

“A UPS will keep going, but if the air conditioning didn't kick on, then it comes down to the question of which will happen first — the battery dies or the equipment melts,” says Jeremy Doran, director of strategic initiatives for the access provider segment for APC.

Operators also must look at how the environment can be controlled efficiently — be it water-cooled, traditional air conditioning or natural convection — and then reduce the amount of energy used in that site, says Kirit Wadhia, director of sales and marketing for Tyco Electronics Power Systems.

“There is no miracle cure. We are working at it a step at a time. But you can see how easy it is for an operator to paint himself in a corner if he doesn't plan a power strategy,” Wadhia says.

Bauer says those in the industry are now more concerned with just how large they should build carrier hotels and data centers because of issues related to power.

“You are now seeing decisions based on where to locate central offices based on the availability of power,” adds Jacques Poulin, vice president of network power systems for Astec APS. “That wasn't the case a few years ago. This has a huge impact on what we do. On the DC side, we used to make a 3000 A power system. Now we have 10,000 A, 20,000 A and 30,000 A installations. This is just the beginning.”

A goal now is to create power systems with flexibility and scalability covering a much wider power range to meet the needs of operators, says Nicklas Fallgren, senior marketing manager for Tyco. As a result, Tyco has developed a “dumb” rectifier with a slot for a typical PCMCIA card used in computers. The card can add controller features to the rectifier and allows the power system to be upgraded by reprogramming or adding a new card in the slot.

“Everybody says they need 150 W of power density. But they don't need it today,” Invensys' Marcotte says. “So you need a power train and platform, redundancy and a migration strategy.”

Showing power some respect

“I went to a CEO summit and they were talking about optical Ethernet, mesh networks, 3G and things like that. They take the power thing for granted,” Marcotte says. “Sure, it is not as sexy as optical Ethernet, but the power system probably has more relevance to some quality of service measurements than any other network feature whatsoever.”

The explosion of broadband — coupled with the availability of smaller and more powerful devices — also is leading to growth in distributed infrastructures, which means a need for power supplies in more places combined with the ability to remotely manage power and cooling in those locations (Figure 3).

Roger Iannetta, APC's global product marketing manager for the DC power systems group, says part of the process is to apply some of the techniques used with IP. “What we've brought into it is manageability. We are applying some of that to the DC products in the telco space with [simple network management protocol], TCP/IP or Web access,” he says.

Klaus Schreier, senior vice president of technology applications for Siemens Information and Communication, says that almost all of the circuitry the company designs today has some type of sophisticated power control. “Power consumption is almost linear to ports and channels supplied,” he says. “When you put more intelligence into channel circuitry and more silicon, the power increases there as well. This is really a challenge. There must be extensive measurements to reduce power consumption.”

Applying network management techniques to a power system also can create an opportunity for operators to use backup systems as primary power sources in order to control costs, particularly in regions where peak power from the grid can be more expensive than running a generator.

“The cost of energy is going up, and reliability of the grid is going down. The issue of power management will be a very, very physical issue in the industry,” Astec's Poulin says.

Astec APS has been talking with battery vendors to see if they can develop ways to use energy stored in battery during peak hours to offload consumption on the grid. “One of the solutions in Brazil, where they have their own energy crisis, is to limit customers to a certain amount of power,” Poulin says. “If they have more draw, then there are severe penalties. I can see in applications, a point of energy management to shift to a local source. During peak hours, this is becoming a real need.”

Astec APS has introduced a new generation switch targeting Brazil as the primary market. The product works like a softswitch on a grid to start generators in a synchronized fashion to supply kilowatts and provide additional energy as needed.

“Network operators need to invest in on-site power generation equipment to provide the quality and reliability necessary to service their customers,” says Steve Goran, national account manager of telecom for Generac Power Systems. “In certain regions today, and more regions in the future, there is the opportunity to leverage this on-site power generation equipment to lower overall energy costs.”

Besides remote management, Poulin says demand is increasing for systems that can manage the load for co-location facilities. “They want features for load shedding and priority load management so that they can offer a service level agreement that can be cut off after an hour or two depending on the power agreement they have signed,” he says.

“You are seeing some sophisticated load management and monitoring that allows operators to disconnect low-grade service contracts while keeping mission-critical operations running,” he says. “We're just seeing the beginning of this.”

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Wayne Walley is editor-in-chief of Global Telephony.