Introduction to Datacenter Power Structure:


While designing power solution for datacenter, we need to consider uptime demanded from client. Uptime of Data center is obviously depends on uptime of power supply. For higher uptime of power supply and hence datacenter we need to design redundant, efficient power distribution network which will offer not only continuous but also clean and safe power supply.  Datacenter Power distribution network typically consist of Power backup devices (e.g. UPS, Generator), Switching devices ( e.g.  STS, breakers) and protection devices (e.g. TVSS, MCCB).


Static Transfer Switch

Voltage Stabilizer

Power Conditioning

As shown in introductory video Static Transfer switch (STS) has two inputs. One input feed from Utility power through transformer and other from Backup Generator. Utility power act as default input while backup Generator as standby input. Output of STS feed to input of Uninterrupted Power Supply  (UPS). To make network more reliable we can connect two UPSs in Parallel redundant mode. In parallel redundant configuration each UPS serves 50% of load. And in event of failure of one UPS, other will serve 100% load without break.  This increases reliability and uptime of data center services. If utility power fails, then Static transfer switch will give signal to  auto start Generator and it will transfer input to Generator from utility power. Load will serve through battery backup of UPS till Generator get start.


Major Components of Server room Power Setup.

Lets have small introduction of different components of Power System for Datacenter and Server room one by one:

  • Uninterruptible Power Supply (UPS): This is Major component of Datacenter Power setup. UPS can be Single or Three phase. It can be standalone UPS or parallel redundant UPS. Up to Six Units can be connected in parallel redundant mode to improve uptime of power. Battery backup can be provided depending on load, site condition and shutdown time.
  • Static Transfer Switch (STS): Static transfer Switch is use to transfer power from one default source to other redundant source without break. It can be connected before or after UPS. Generally two input to STS are power from local grid and power from Generator & output of STS connected to input of UPS.
  • Voltage Stabilizer: It is use to stabilize input voltage c0ming from Grid or Generator. It is used for data center site which has low quality power supply. Traditionally,  voltage stabilizer with servo motor controlled technology are commonly used. Static voltage stabilizer is based on new technology which has fastest voltage correction time than servo motor based stabilizer.
  • Power Conditioning Equipment: It includes electrical equipment like isolation transformer, Transient Voltage Surge Suppressor (TVSS), Active filters, MCBs, Brakers and isolators which use for conditioning and safety of power.

Understanding Power Structure of all Tier Data center.

Lets understand Power structure of all Tier of Datacenter. Certainly lower  Tier datacenter will have less power redundancies of power component Than higher Tier Datacenter.

Tier I Datacentre (Server Room)

Tier I Datacenter (Server Room)

Tier I datacenter has single power distribution path without redundancy to any power components. In this type of power distribution network though IT load and Mechanical load separated but there is Single UPS to serve IT load. Hence this type of distribution has multi points of failures and human errors. To do maintenance or failure repair, this network needs shutdown of IT load.  Uptime of Power network is around 99.67% with 29 hours of per annun downtime. Per annum two scheduled maintenances, each of 12 hours shutdown. This type of power distribution network use for small enterprises internal server room which has let critical index factor.

Datacenter Tier 1 Power design consisting on UPS and Generator.

Tier II Data Centre

Tier II Data Center

With Tier II type power distribution network, power uptime of datacenter get improved but still network is prone to multi point of failures and human errors. In Tier II power distribution design, redundancy provided to critical components like UPS and Generator. UPS connected in parallel Redundant mode which means each UPS shares 50% load and will take over 100% load without any break in event of failure of other UPS. Generator also connected to same bus sharing 50% load by each Generator. Uptime of Power network is around 99.75% with 22 hours of per annum downtime. Three scheduled maintenances every 3 years, each of 12 hours shutdown.

Data center Tier 2 power distribution design.

Tier III Datacentre

Tier III Datacenter.

In Tier III datacenter, redundancy provided to all components including distribution path. In event of failure in main distribution path, other can supply power to IT load. UPS, Generator and distribution path are redundant. But still there are failure point and human errors can cause shutdown. This type of network do not need scheduled maintenance. Two distribution paths allows concurrent maintenance. This increase uptime to 99.98% with maximum downtime of 96 minutes per annum. Major mechanical load is powered by Grid or redundant Generators. But critical mechanical load like drain pumps, Fans etc. are powered through UPS.

Server room Tier 3 power distribution network design.

Tier IV Datacentre

Tier IV Datacentre

Power distribution design of Tier IV datacenter is most robust and has highest up time of 99.99% with downtime of only 48 minutes annually. It this design not only two Generator, Grids & distribution paths are redundant, but also each component in respect distribution path is redundant. There is not single point of failure. This design can withstand faults, human errors & fire situations. Construction of Tier IV data center is costly affaire since it required all redundant equipment.

Power Network with UPS, Voltage stabilizer, TVSS, isolation transformer.

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