# Data Center Cabinet Load Balancing:  there’s a less complicated way.

Posted on March 28, 2017 by Gento

Without going into the complicated math, suffice it to say that load balancing in a 3 phase system is desirable.  The more unbalanced a system the more problems it creates.  UPS life, for one, can be affected by unbalanced systems.  Although one circuit (server cabinet) being out of balance won’t have much effect, if many or all circuits on a panel are out of balance, the main circuit supplying the breaker panel will be out of balance and this can ruin your upstream UPS.  There are also efficiency issues with unbalanced loads.

How is load balancing currently accomplished in a rack cabinet?

To balance a load in a cabinet, the loads of the equipment power supplies are spread across the 3 phases – L1/L2, L2/L3, L3/L1.  This is done by plugging the first server (or switch/router) in an outlet wired on L1/L2, the next server on L2/L3, the next on L3/L1, then start over.  The goal is to get an equal number of devices/loads on all 3 phases – or as close as possible.

This approach can quickly turn into a cabling nightmare. Most rack PDUs are linear in their phase layout of outlets – there are only three banks of outlets, one for each phase.  For example, on a 36 outlet PDU, outlets 1 through 12 will be on L1/L2, 13 through 24 on L2/L3, and 25 through 36 on L3/L1.  If you use the above method of balancing, and start racking the devices at the bottom U position, the third device you plug in will need to reach the top third of the PDU and the last device may have to reach back to the bottom of the PDU.  In other words, a lot of crisscrossed cabling.

How do Raritan’s balance the cable and load balancing challenge?

In certain Raritan PX three-phase models the architecture gets around the cabling issue by staggering the grouping of outlets - there are at least 6 banks of outlets.  For example, outlets 1 through 6 are on L1/L2, 7 through 12 on L2/L3, 13 through 18 on L3/L1, but then we start over at L1/L2 for outlets 19 through 24. (See Illustration below)

This intelligently engineered architecture results in more reliability and easier execution.  The devices towards the top of the cabinet don’t need to be plugged in to the bottom of the PDU and devices at the bottom don’t need to be plugged in to the top.

The Result

By using Raritan’s alternate circuit phase sequencing, you will be able to more easily and efficiently balance your cabinet load. The approach simplifies deployment of IT devices and balances the three lines to get the most power headroom.  Also, tracing a power cord to a device becomes much easier and thus, unplugging the wrong device during maintenance or replacement will be less likely. Resulting in less downtime… always a good thing!

#### Other Blog Posts

8 Essential Tips When Investing in Remote Access Solution
Posted on June 23, 2020
KVM Remote Management in the COVID-19 Pandemic Era
Posted on June 15, 2020
The New Dominion LX II: Why You Should Trade Up
Posted on April 2, 2020
Coronavirus Remote Management Checklist
Posted on March 18, 2020
How to Keep Business Going During COVID-19 Outbreak
Posted on March 2, 2020

View all Blog Posts

#### 近期活動

Data Cloud India
February 5-6, 2020  •  Mumbai, India
Industrial Automation
April 24, 2020  •  Tainan, Taiwan
DigiTimes Data Center Forum Taipei
May 8, 2020  •  Taipei, Taiwan
Cloud & Data Center Convention (Wmedia)
May 14, 2020  •  Manila, Philippines
Industrial Automation
May 14, 2020  •  Taipei, Taiwan

View all Events

#### Raritan最新新聞

Raritan 推出中小型企業專用的新一代經濟型 KVM-Over-IP 切換器與序列存取
Posted on March 16, 2020
Extended IT rack power mapping possibilities with Raritan’s locking solution
Posted on October 23, 2019
Raritan Ranked as the Global Leader in KVM-over-IP Switches
Posted on October 21, 2019
Raritan 推出新款 KVM-over-IP 使用者工作站，為遠端設備存取提供 4 K 效能與生產力
Posted on September 18, 2019
Raritan 的全新 4K 超高畫質 KVM-over-IP 切換器榮獲 NAB 最佳展品大賞
Posted on May 22, 2019

View all news