Learn Why Alternating Phase Is the Perfect Load Balancing Solution


Server Technology takes a unique approach to the placement of the outlets on the power strip with a method called "Alternating Phase". Traditional PDUs have the X, Y, and Z phases grouped together:  X,X,X; Y,Y,Y; Z,Z,Z.  In an Alternating Phase configuration, those phases are grouped X,Y,Z; X,Y,Z; X,Y,Z.  Plugging into a different phase is then a matter of inches, not a long power cord run to the bottom of the rack. To get a visual, take a look at our HDOT Alternating Phase Flyer to see pictures of the resulting differences between the two methodologies.

Alternating phase outlets alternate the phased power on a per-outlet basis instead of a per-branch basis. This allows for shorter cords, quicker installation and easier load balancing for 3-phase rackmount PDUs. 

Key Benefits

  • Easier load balancing for three-phase PDUs: Load balancing is necessary for reasons related to safety and power efficiency; unbalanced power loads, for instance, can cause uneven voltage and current measurements, which can be harmful to your equipment. Unbalanced loads can also trip your circuit breakers. Whereas load balancing can be a confusing and time-consuming task, the alternating phase PDU arrangement allows you to alternate phase pairs on a per-outlet basis. The result is less clutter and shorter cords.
  • High native cord retention: Accidentally disconnecting power cords from their outlets occurs frequently in the data center, especially when moving equipment. Traditionally, the solution was to invest in expensive, custom ancillary cord-locking devices for each outlet. HDOT (High Density Outlet Technology) Alternating Phase PDUs streamline the process by using high native cord retention, which holds plugs firmly in place while they are attached to an outlet. So, once you plug a device into an HDOT Alternating Phase PDU, you can rest assured that it will stay exactly where you put it.
  • Custom configured: When purchasing a HDOT Alternating Phase PDU, you can choose a configuration that meets your exact needs using Server Technology’s ‘Build Your Own PDU’ configurator, in just four simple steps.

Want to learn more about Alternating Phase?  Take a deeper dive with this white paper.