• Increasing Power Capacity
In 2017, the annual run rate for global IP traffic
was 1.5 XB per year or 122 exabytes (EB) per month.
Annual global IP traffic will reach 4.8 ZB per year by
2022 or 396 EB per month.4 The rapid increase in data
traffic and in computing demand are driving the need
for maximizing the amount of IT equipment that can
be placed in a cabinet or rack. This trend provides
a special challenge for the rack power designers;
they need to find the power capacity to power
all this equipment.
To resolve this challenge, many electrical designers
are looking toward bringing 415V to the rack and are
also utilizing three-phase power. Consider an example
(Figure 1) of a 30A 415V three-phase wye circuit with
five wires, which is only 1.7 times the number of a 30A
208V single-phase circuit with three wires, but can
provide more than three times the power capacity.
Single-Phase Power Capacity = Amps x Volts = 24 x 208 =
4,992 VA
24 x 415 x 1.732 = 17,251 VA
It is important to note that the 30A has been
de-rated by 80 percent to 24A to meet UL and good
design practices in North America. It does not affect
the outcome as it was done for both voltage levels.
July/August 2019 I 57
Rack PDUs have evolved to support these trends.
In the past, a rack PDU would simply provide power
and maybe some level of surge suppression for the active
equipment in the cabinet. Today, the rack PDU must
operate at full load in high temperatures, participate in
support of environmental data collection, and assist in
maintaining secure access to the cabinet. The rack PDU
is becoming a data aggregation point in the cabinet with
intelligence and control capable down to the receptacle.
DATA CENTER CHALLENGES
Data Center managers and designers are asking the
question: How do they retrofit or newly architect a data
center that can handle the ever-increasing traffic, adjust
to the elevated power and heat strains on equipment,
and provide for environmental and security monitoring?
To address this question, consider the four major
challenges centered around managing capacity, energy
cost, maintaining uptime and security.
Managing Capacity
Managing capacity includes how to optimize and maximize
utilization of the existing capacity and the ability
to plan and forecast for future needs. It is estimated that
28 percent of the capacity in the data center is not fully
utilized3 and can be recaptured. Capacity is defined as
power capacity, cooling capacity, and space capacity. All
three elements (i.e., power, cooling, and space capacity)
are necessary together to place equipment in the cabinet.
FIGURE 1: 30A 208V circuit with 5kVA capacity and 30A 415V circuit with 17.3kVA capacity.