Data Center Power Infrastructure, Data Center Power Infrastructure explained, how is power distributed in the data center, what is the use of the generator in the data center

1. Data center Physical infrastructure
Typically there are four primary physical key constraints that is the major factor for
the successful operation of a data center and those are
• Power
• Cooling
• Connectivity
• Space
Each of these constraints is having its own unexceptional roles to the success of our
data center. Let’s have a look into each of this in details and by the end of this article,
you will definitely understand the importance of these.
Power Infrastructure
When you consider the importance of electric power, you know that each and every
mechanical, electrical and operational parts require to utilize the power in order to
function properly. Even though the utilization rate will vary depends on the areas of
devices, electrical infrastructure is the most important part among these four
constraints. We can say that the power distribution system is the heart of any critical
facility, and it's vital that everyone working in and around critical sites knows at least
the basics of the power distribution system.
There are multiple electric components involved in a data center. The electric power
distribution structure from the utility power to the rack PDU(Power strip) is generally
known as Power Train. Let us see this in a picture format as below,

2. So let me tell you a data center that is having N+1 configuration will have below
electric components to support the electricity infrastructure.
• Main power input
• Medium-voltage switchgear including MV/LV transformer
• Low-voltage switchgear/switchboard
• UPS system with input/output switchboard and UPS distribution switchboard
• Switchgear
• Motor Control Centre (MCC)
• Panelboard
• Power Distribution Units (PDUs) and Remote Power Panels (RPPs)
• Rack power strips
Remember to verify the same when you get a chance to do your data center tour
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Let us have a look into each component that fulfilled the power train(picture on top)
for the understanding of its function.
Utility Power
Here is the source of your electric energy, without the utility power we would have
never achieved a power solution in a data center. The power from the utility will be
always consumed for the operation which is bypassed through generator set. In any

3. circumstance where there is a lack of utility power, the generator set will take
control of this operation. The power supply of every larger data center starts with a
connection to the main grid, which is provided by the local utility company.
Data center main power supply is in three-phase distribution. It is usually used in the
industry to drive motors and other devices. The current which is mainly distributed
in the data center is Alternate current(AC). If your region is following UK standards
the main electricity supply is at 50 cycles per second and hence it can be said as 50
Hz, if this is a US standard then we would say that it will be 60Hz.
Generator Set
If the Utility power becomes unavailable, the ATS triggers the emergency source. In
most data centers, that means the on-site generators. The function of the
backup generator is to provide power when there is an interruption of main
power. Data center components do not easily tolerate power spikes due to switching
from a normal to the emergency power supply. When these components loose
power (if only for a fraction of a second), a total restart is required. This could allow
for system downtimes, startup issues and loss of in-process information.
When utility power is lost in the facility the following chain of events occur,
• UPS supplies power to security and data center
• Emergency generator starts and automatic transfer switch transfers to
emergency power
• Switchgear routes power to Critical and Non-Critical loads

4. • UPS transfers to normal operation, Data center and security are powered
by an emergency generator
• When normal power is resumed, the automatic transfer switch routes power
to utility and critical and non-critical loads are powered.
Data center and security see no power interruption and continue to operate
normally through power loss. Components such as HVAC and work stations may
need to be reset to regain normal operation. Often work stations contain individual
UPS backup to keep computers powered for a short amount of time.
Main switchboard (Main PDU or Switchgear)
As you can see from the power train diagram, the power from utility is directly
running to the main switchboard and we can say that electrical power is presented
to the data center through a switchboard (or switchboards).
The incoming circuits are split into a number of outgoing circuits to feed different
areas or loads within the data center. The outgoing cables are protected by an
appropriate fuse or circuit breaker, such that a fault on any circuit will only affect
that circuit and not trip out the entire facility. The cables feeding loads may be single
or three phase, and will also contain neutral and earth conductors.

5. Note: The feeds from the utility provider are high voltage and low current, which
allows them to utilize smaller conductors for greater distances.
UPS(Uninterruptable power supply)
Uninterrupted Power Supply (UPS) systems are to ensure safety,
security and continuity of operations in harsh environments. The usage and capacity
of a UPS in data center environment purely depend on the data center design and
operation. Some data centers are not using UPS power supply and instead, they
design their diesel generator with DRUPS(it stores kinetic energy to kick start the
generator). Whereas most of the data centers use static UPS as a backup instead of
DRUPS.
UPSs vary greatly in physical size, weight, form factor (e.g. standalone vs. rack-
based), capacity, supported input power source (e.g. single phase vs. 3-phase),
technological design, and cost. There are a number of design decisions to make
relating to a UPS for a data center (or other mission-critical facilities) such as:
• The size of the load to be protected
• The battery runtime required
• The proper input and output voltages
• The right type of system (on-line, line-interactive)
• Pricing and performance seen within manufacturer product portfolios

6. • The advances in technologies
• The ideal level of redundancy (i.e., N, N+1, 2N, 2N+1, etc)
• The required output distribution
Backup time of a UPS - This is the time during which the UPS can supply the rated
load with power from its battery under nominal conditions when the normal AC
source fails. This time depends on the battery. Typical backup times can be designed
to last up to 30 minutes. Industrial UPS systems often include specifically designed
NI-CD battery arrays that withstand harsh conditions and provide long hours of
reserve power when necessary, especially in remote areas subject to extreme
temperatures.
Another UPS system benefit is the ability to clean the incoming utility power. Normal
utility power voltages vary wildly depending on what other loads the service is
supplying. These voltage fluctuations are detrimental to power supplies in servers
and can shorten their life spans or worse: Destroy them. UPS units clean electrical
power by converting utility power from AC to DC and back to AC again; this process is
referred to as "dual conversion”.
Power distribution unit(PDU)
PDUs are not clearly defined by standards, and they come in many configurations,
although they all have common features and functions. Their basic function is to
distribute power to the racks, either through cables and sockets or via an overhead
bus-track system. There are three main types of PDU:
• Dumb (No instrumentation - not manageable)
• Metered (Equipped with a display showing current load on each phase)
• Switched (Receptacles can be individually switched on or off remotely)
One challenge in selecting PDUs is to balance the relatively high cost, great
functionality and low risk of a switched PDU, versus the relatively low cost (but
higher risk and lack of manageability) of a dumb PDU.
With a dumb PDU, a data center power supply runs the risk of phase unbalancing;
devices may be unexpectedly plugged in, possibly tripping a circuit breaker. This
could result in an unplanned "emergency" shut-down of critical equipment, causing
data loss or corruption, and costly hardware damage.

7. Dependent on the quality of the incoming utility supply, PDUs may be fitted with
internal transformers where the power quality is prone to fluctuations.
Remote power panel(RPP)
Remote Power Panels (RPPs) are like PDUs without a transformer and are therefore
smaller (about the size of a standard raised floor tile). RPPs may contain up to four
panelboards and a monitoring system, and distribute power to the IT racks. RPPs are
most often fed from one or more PDU sub-feed Breakers. Usually, RPPs are located
in the IT space(white space area) to distribute, control, and monitor the critical
power from the upstream UPS system to IT racks.
Some of the advantages of using Remote Power Panels are as below,
• Reduce the length of cable runs between your PDU and the individual loads
• Optimize usable floor space
• Simplify server consolidation plans
• Meet growth demands
• Retrofit to any existing distribution system
• Come with an integrated energy management system
Rack Power strips

8. Rack power strips are installed in IT racks and are powered from the mating
connector of the upstream PDU or RPP.
There is a wide range of options are available for this. It can be single-phase or three-
phase, horizontal or vertical in shape, metered or unmetered and IP-addressable for
remotely managing and monitoring.
Importance of power protection
So we have seen the major components included in electricity infrastructure for data
centers. So how important it is to have the power highly available in a data center?
Let’s see some of the facts that can happen after a power outage for IT systems.
• More than 33% of companies require more than one day to recover
• 10% of companies take more than one week
• It can take up to 48 hours to reconfigure a network
• It can take days or weeks to re-enter lost data
What are the causes of Data Centre Power Outages and how can we prevent it?
There are four main areas responsible for power outages at data centers.

9. • Insufficient/inconsistent operational testing and monitoring.
• Lack of redundancy in design and implementation.
• Lack of system-level power control management.
• Lack of proper preventative maintenance.
And most frequently - Human Error! L
By the above notes, we have completed the major power infrastructures involved in
a data center. We will discuss the physical infrastructure of the Cooling system
on the next article.
Have a comment or points to be reviewed? Let us grow together. Feel free to
comment.