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Three Questions to Ask About Three Phase Power Distribution

Posted by RJ Tee on Mar 10, 2017 9:30:24 AM

Across the globe, data center managers are making the move to 60A service at the rack level. Why? One big reason is because it better supports higher-density applications. As a result, three-phase power distribution is seeing a boost in popularity. Put simply, it just makes sense for data centers from economic and efficiency standpoints.

A popular choice for those looking to make the move to alternating phase power is the HDOT Switched power distribution unit from Server Technology. These rack-mount PDUs simplify time consuming processes such as cable management and load balancing. Offering up to a 30 percent footprint reduction, HDOT PDUs let you install more servers per rack and create a much more efficient flow over standard one- or two-phase power by using three-phase power distribution.

As you weigh your options for power distribution solutions, it’s crucial to ask all the right questions. In particular, you should train your focus on the issues of load balancing, its impact on power bills and related power loss.

Questions to ask when considering three-phase power distribution:

  1. Are my phases properly balanced? If all three phases aren’t correctly balanced, more heat will be generated. This leads to higher cooling costs.
  2. What’s the impact on my power bill? When loads are unbalanced, inefficiency follows, and so do skyrocketing power bills.
  3. Am I running too high of a load on my single phases? This is a risky approach and can result in tripped PDUs and upstream breakers. This leads to power loss at the rack level.

Opting for a switched rack-mount PDU from Server Technology can help alleviate the potential problems of a single- or two-phase load by distributing alternate phased power on a per-outlet basis rather than per branch. And, when you choose an HDOT unit, you’re getting the highest outlet count in the most compact form factor on the market.

As densities and power in the racks continue to grow, and as data center managers install more and more gear in the cabinets, it’s no secret power requirements are also rising. With an HDOT Switched rack PDU in your corner, you’ll not only survive, but thrive when it comes to efficiency and savings.

Topics: HDOT, Alternating phase, HDOT Switched, three phase power

Single vs. Three Phase Power Distribution - Know the Difference

Posted by RJ Tee on Jan 30, 2017 9:48:00 AM


Electricity is the single most important resource in a data center, as it’s needed for powering every system — from the servers on the floor to the lights overhead.

At the same time, electricity is incredibly expensive, dangerous and easy to mismanage — especially when considering the sheer volume of power that is typically used. Some facilities, after all, use enough electricity to power hundreds of thousands of homes. Even though energy efficiency is now top of mind for data center administrators, there’s no getting around the fact that data centers consume a great deal of power. As such, it’s vital to have the correct underlying power distribution system in place before moving in and setting up any equipment.

Many customers, however, are still asking whether they should use single or three-phase power in their data centers. This article will explore the basic differences between the two systems.

What makes these systems different?

Single-phase power systems distribute up to 120V of alternating current. This current is distributed over two wires: A single, active conductor and a neutral one. The current changes size and direction at regular intervals. Single-phase wires are usually grounded at the switchboard.  

These systems are mostly used in residential settings that have small workloads. They are rarely used in data centers today, as the majority of cabinets are too dense and require more electricity than single-phase systems can provide. And this is where three-phase systems come into play.

What makes three-phase power distribution the better choice for data centers?

Three-phase power systems are comprised of three alternating currents, each varying in phase by 120 degrees.

To illustrate the difference between single and three-phase power distribution, think of waves crashing onto a beach. Normally a wave crashes, recedes back into the ocean and then a few seconds later another wave follows. This is like a single-phase alternating current.

Now, imagine there is no time between waves as they crash onto shore. As soon as one wave hits, another is there to follow, and then another. This is what three-phase alternating current looks like. The power flow never ebbs; it always flows. It’s the difference between using a single 120V alternating current for power, versus one that combines a 208V circuit with three more 120V circuits.

So, if someone is recommending single-phase power distribution for your data center, make sure you get a second opinion from a certified power expert. If you are operating a large data center that is carrying heavy workloads, you should strongly consider using a three-phase power distribution system.

Server Technology offers a variety of solutions that support three-phase electricity systems, as well as the Sentry Power Manager (SPM), a centralized data center power monitoring and management platform. 

To learn more about Server Technology, click here.

Topics: three phase, single phase, three phase power

Want To Support High-Density Applications? Try Three Phase Power Distribution.

Posted by Josh Schaap on Apr 8, 2016 11:08:39 AM


Sometimes, the road less traveled proves to be the better route. That’s certainly the case with a less common, new approach to PDU design that employs three-phase power distribution. In the past, this has meant dividing power into several branches within the rack PDU, but this new approach from Server Technology makes use of alternating each phase on a per-receptacle basis instead of per branch. As you can imagine, demand for more power in the cabinet is behind the move toward three-phase power distribution in many data centers. If the search for more power is on your mind, alternating phase PDUs might be the answer to your problems.

When an installer is installing new equipment in a computer rack, he often only thinks of powering up the equipment. The principles of three-phase power are not generally at the top of mind during the install process. However, it’s crucial for installers to understand load balancing for several reasons:

  1. If the three phases aren’t properly balanced, heat is generated, which jacks up cooling costs.
  2. An unbalanced load can result in inefficiency and higher power bills.
  3. Higher loads on single phases can translate to higher risks with tripping PDUs and upstream breakers, thereby causing power loss at the rack level.

The best practice is to install rack mounted equipment, allowing you to draw a similar current on each branch. This, of course, is in a perfect world where the rack is only filled with a single type of device. In most data centers, mixed devices are the reality, causing a tangle of power cables in the back of the rack, which can inhibit airflow, adding to heat problems.

These and other issues are easily resolved by using alternating phase PDUs, which are specially designed to alternate phased power on a per-outlet basis instead of per-branch. When you use an alternating phase PDU, power wiring gets a lot simpler because power cords no longer need to be stretched across the vertical PDU to reach the separate branches. This allows you to use shorter power cords, resulting in a cleaner back of the rack. These cords also result in lessened cable resistance and lowered power dissipation. Assembling the rack also gets quite a bit easier with a reduction in assembly time. Important to note: shorter cords simply result in less mass, meaning they’re less likely to come unplugged during rack transport.

Other reasons to choose alternating phase PDUs:

  • Installers can plug in servers from the bottom to the top of the rack with lowered risk of blowing breakers.
  • Server Technology’s patent pending alternating phase power distribution use multi-layered circuit boards instead of wires to separate the phases.
  • Alternating phase PDUs help reduce heat build-up.

As many data centers move to 60A service at the rack level to support high-density applications, three-phase power distribution solutions such as these are becoming more and more common. Learn more about our all-in-one PDU solutions and get more details on traditional vs. three-phase power distribution techniques in the white paper “Alternating Phase Power Distribution at the Data Center Rack PDU” today.

Topics: data center power, rack PDU, three phase power