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3-Phase Voltage for Data Center Agility

Mike Peterson

In the world of data centers, there’s a lot of talk about voltage and power deliverythe best options, the most efficient choices, the latest voltages, etc. Oftentimes, three-phase voltage is the power delivery method of choice.

As a combination of three single-phase circuits that deliver power so the load is the same at any point, three-phase voltage allows utilities to deliver more power over smaller, less expensive wires. If three-phase voltage is what you have to work with in your data center, there are ways to make the most of it.

 

3-Phase Voltage Offers Flexibility

Although other voltage options exist, the most common three-phase voltage is 208V power as a feed to the rack. A three-phase voltage is 120V phase to neutral and phase-to-phase voltage of 208V (see Three-Phase Power: Wye It Matters for more information). This indicates that line-to-line (L-L) voltage is 208VAC in a wye configuration; the line to neutral (L-N) voltage is 120VAC. This voltage provides necessary flexibility in your data center.

  

Using a power distribution system that supplies all three phases (e.g., neutral, ground-to-rack & L21-20 or other type of amperage & plug style) offers several options to help ensure quick and easy upgrades down the road.

 

Three-phase voltage also allows you to have 120V or 208V outlets; you can mix and match types in a single PDU (power distribution unit) or have one voltage cover the entire strip.

 

Implications of Three-Phase Voltage & What It Means for You

Image of goldfish jumping from small to larger fish bowl

If you’re a co-location data center, offering equipment, space and bandwidth for rental, three-phase voltage delivers the ability to support a wide range of customers.

 

If your co-lo data center is attempting to standardize parts, you may not need 120V or 208V (or both) in a rack. If you choose three PDUs and select an outlet with an L21-20 receptacle for the PDU to plug into, the only thing that needs to be done if the voltage changes is to change the PDU-not rewire. This translates to no scheduled downtime and the elimination of hazardous hot or live electrical work by electricians.

 

If you want to futureproof your data center, three-phase voltage enables 120V today and using a three-phase outlet with L21-20P allows for upgrades or adding 208V with a simple PDU change. Because this switch can be made quickly, speed to re-deploy, upgrade or perform MAC work will increase. 


Belden has a wide range of PDUs and power strips to support any of your data center’s three-phase voltage needs, from a variety of input voltage and amperages and outlet combinations to monitoring and management capabilities.

 

A few hints as you explore Belden’s PDU options:

  • L6-XX—“L” refers to locking & “6” indicates 208V, two hots and a ground.
  • L21-XX-"L" refers to "locking" & "21" indicates 3 phases, three hots, a neutral & ground. The presence of a neutral wire means the PDU can be 120V or 208V (or both).

For more information about Belden’s PDUs, visit  Three-Phase PDUs page.