Emerson Liebert NX 40-200kVA White Paper

Power and Cooling Design Guidelines for
Network Access Rooms

A White Paper from the Experts
in Business-Critical Continuity

TM

Introduction

Network access and telecom rooms are
housing more powerful and critical
equipment as businesses rely on these
spaces to support an increasing number
of business-critical applications. The
technologies supporting the deployment
of IP telephony, wireless networking,
converged applications, and other
equipment outside traditional IT data storage
and management are finding their way into
nontraditional spaces that weren’t designed
as data centers. These rooms also support
important operational functions including
time and attendance equipment, building
maintenance alarms and security equipment.
In the event of a failure within a network
access room, organizations may be
susceptible to the disruption of
revenue-generating activities or the
inoperability of security and phone systems,
among other serious consequences.

Because network access equipment has
traditionally been housed in converted
closets or other spaces not well suited
for electronics, its reliability and that of
newer devices has been placed in jeopardy.
These spaces often constrain growth or
enhanced use of the closet because of the
lack of physical space and power/cooling
infrastructure required to support the
powerful and critical equipment on which
the business is now dependent (Figure 1).

More powerful equipment generates more
heat. When the equipment is trapped in
a small, poorly ventilated space, heat can
quickly raise the temperature to unsafe
levels that reduce performance and shorten
equipment life. Additionally, the hardware
running these applications requires higher
availability power protection through an
uninterruptible power supply (UPS) system.

Threat to Business Continuity

For example, Voice over Internet Protocol
(VoIP) can change the economics associated
with network access downtime by adding
significant costs to a business should there be
a disruption. When evaluating the criticality
of network and telecom closets, IT managers
should review applications supported by
the network and evaluate the impact to
the business if those applications become
unexpectedly unavailable. Addressing costs
associated with employee productivity and
revenue-generating activities should not be
overlooked. As downtime costs rise, so too
should the investment in technologies that
can increase availability.

Configuring the appropriate solution involves
both overcoming the physical challenges
imposed by the space and understanding the
cost of downtime for the environment. The
good news is that there are solutions available
today that allow powerful and sensitive
network equipment to operate safely and
reliably in almost any environment.

Figure 1. New switches, routers and other
equipment being deployed as part of an IT
system upgrade may require enhanced power
and cooling support.

Evaluating the Physical Environment

The network access room environment poses
a number of challenges for power, cooling
and monitoring systems. Evaluation of the
network closet’s size and existing power
and cooling attributes will help ensure that
it is designed with solutions that can easily
support growth and flexibility as business
needs change.

More powerful

equipment generates

more heat. When the

equipment is trapped

in a small, poorly

ventilated space, heat

can quickly raise the

temperature to unsafe

levels that reduce

performance and

shorten equipment life.

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Module Capacity Size

Cost per Capacity Unit

Smaller UPS modules

Larger UPS modules

The advantages of

a centralized UPS

with larger, more

robust technology

include lower cost

of ownership and

higher system

availability because

of fewer potential

points of failure and

easier management.

This approach also

simplifies service

and maintenance

requirements.

Size

The small size of network access rooms
can limit power and cooling equipment
configurations. Most network access room
installations require UPS systems that will
take at least 2U of rack space, not including
extended runtime batteries.

Existing Cooling

Cooling and ventilation will determine how
effectively heat can be removed from the rack
and from the access room. Equipment type
and access room size will largely determine
cooling requirements. Simple ventilation
may suffice, or a dedicated cooling system
may be warranted. Initial considerations
should include ventilation of the access room,
ducting of walls and ceilings, and year-round
availability of building air conditioning.

Existing Power

When evaluating a room to handle network
equipment, check out elements of the
room’s existing power supply to see if it can
adequately support the technologies that it
may house.

These factors, along with building layout
and network equipment criticality, will drive
the decision on whether to use centralized
or decentralized UPS systems. Some
organizations may be able to utilize a single
UPS located in a computer room to protect
network access rooms throughout the same
building. The advantages of a centralized UPS
with larger, more robust technology include
lower cost of ownership and higher system
availability because of fewer potential points
of failure and easier management (Figure

2). This approach also simplifies service and
maintenance requirements.

The size and number of circuits required
are determined by power usage and
redundancy requirements. Support for Power
over Ethernet (PoE) can quadruple power
requirements. Certain redundancy strategies,
such as “dual bus” may require more than one
circuit for UPS systems. If additional circuits
must be added, it is wise to provide some
room for future growth as new PoE
standards will allow the format to support
higher-powered devices such as laptops.

Also, the type of wall receptacles in the
access room will impact compatibility with
UPS systems. For example, UPS systems
with capacities of more than 2,000 VA
have different plug types that may not fit
the commonly used 15 amp or 20 amp
receptacles in network access rooms.

Figure 2. Larger UPS modules leverage
economies of scale to drive down the cost
per kW.

Others may adopt a decentralized strategy
in which UPS systems are located in each
rack or access room. Advantages of this
strategy include simpler installation and lower
initial cost. Highly reliable, rack-mounted,
line-interactive and double-conversion UPS
systems are available from 700 VA to 10
kVA, making it practical to deploy power
protection in almost any environment housing
rack-mount servers, switches and routers.
Also, new 208V UPS systems increase the

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ability of IT and network managers to adapt
to the requirements of modern applications
and IT equipment, including servers, routers
and switches that can handle either 120V or
208V power with no modifications necessary.
If decentralized power protection is used,
be sure to account for UPS losses when
determining room power requirements.

Determining Network Hardware
Requirements

Network hardware required for converged
applications will require a high-availability
infrastructure that may have more in
common with systems used in the data
center rather than those traditionally used in
network access rooms.

Again, VoIP may elevate network criticality.
Whereas power availability for phone
systems was traditionally provided by phone
companies,
organization.

today it is the responsibility of each

Converged applications should
be supported with higher power availability
– up to 99.9999 percent – to withstand
between 31 seconds and 5.2 minutes of total
annual downtime.

Most general network access applications
use a line-interactive UPS, such as the Liebert
PSI. This type of UPS provides extended
battery capacities, some power conditioning,
and delivers solid backup power protection
for a wide variety of applications if full power
conditioning or a fault-tolerant design is
not required.

High availability

protection for network

access rooms can

be realized through

deployment of reliable,

flexible and cost-

effective solutions

that provide necessary

levels of power quality,

power reliability,

cooling and ventilation,

remote monitoring and

management, physical

security, and preventive

maintenance and rapid

response service.

Achieving High Availability Protection

High availability protection for network access
rooms can be realized through deployment of
reliable, flexible and cost-effective solutions
that provide necessary levels of power quality,
power reliability, cooling and ventilation,
remote monitoring and management,
physical security, and preventive maintenance
and rapid response service.

In many instances, most of this critical
network equipment will be stored together in
a rack. It’s imperative to use a rack equipped
with ease-of-use design flexibility that allows
for the quick installation of new technologies.
Physical security will be enhanced with a
locking door, which should be perforated to
improve airflow to reduce heat, helping to
ensure higher availability.

Power Quality

The criticality of the network equipment will
determine the type of UPS required. Does
the network equipment only need power
backup during outages or does it require
continual power protection and conditioning?

For business-critical, always-on applications,
a true online, double conversion UPS, such
as the Liebert GXT, is a preferred choice.
A double conversion UPS delivers a lower
total cost of ownership, provides highly
effective power conditioning, and relies less
on the battery system to correct for power
anomalies, extending battery life. It also
protects against UPS component failures,
including premature battery failure from
overheating, power overload and failure
of the internal inverter. True online UPS units
have higher reliability than line-interactive
systems because they include a fault-tolerant
design with an internal bypass that maintains
power during any of the above circumstances.

Midsize, three-phase UPS systems, such
as the Liebert NX (Figure 3), can provide
highly reliable centralized power protection
for multiple network access rooms from a
single location. These systems can introduce
capabilities not available in smaller UPS
systems, such as software scalability, which
allows capacity growth without adding
hardware, and uneven paralleling, which
permits different size modules to operate in

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