There are many considerations when selecting a data center facility or colocation provider such as location, security, and support. However, one of the most important and often overlooked criteria when evaluating data centers is power. In this article, we will examine all of the important power terminology and calculations that you need to know before starting your colocation project.
Why Power is So Important?
Power is the critical element that brings a data center to life and keeps your IT infrastructure up and running even during a disruption. I cannot stress enough the importance of power in the data center. It’s also one of the most important factors in calculating costs for colocation services.
When you understand the role of data center power, you will be able to make the best choice for your business when evaluating data centers and colocation providers.
Data Center Power Terminology
There are two different types of power circuits used to power your servers, switches, routers and related IT infrastructure. They are Alternating Current (AC) and Direct Current (DC).
Alternating Current (AC) Power Circuits
It was Nikola Tesla that won the electricity war against Edison and thus Alternative Current is used universally in the world. It’s what you think of when you plug in any electronic device, appliance or tool into an outlet. With AC power, you’re able to access on-demand power and currents such as 110V, 120V, 208V, 220V or 240V. Simply plug in your devices and you’re ready to go.
Alternating Current (AC) allows voltage or current to change polarity or direction, respectively, over time. For colocation customers, AC power circuits are the most prevalent. This is especially true for enterprise, rack-mounted servers and storage devices.
Direct Current (DC) Power Circuits
It was Thomas Edison that promoted Direct Current (DC) power circuits during the electricity war. With DC power, the electrical charge or current flows in one direction rather than changing direction like AC power.
You experience Direct Current power when you use batteries for your laptop or phone. DC power circuits are also used in the data center. They are most commonly found in Uninterruptible Power Supply (UPS) systems. UPS is used to transition power sources from the utility power grid to diesel generators during a power outage.
DC power circuits are also used to power-related IT hardware and networking gear in the data center including items such as network routers and switches.
Ampere (Amp)
What are Amps? Ampere, abbreviated as (Amp), is the electromagnetic force between electrical conductors carrying electric current. In other words, it is the amount of electricity that runs through the wires to your devices such as servers and other equipment. All of your electronic devices, from your laptop to servers, use a specific number of ampere ‘amps’ to run.
Example Product Label:
INPUT 100-240VAC 8A MAX, 50-60HZ
OUTPUT 500W MAX +12V 44.5A MAX
Volt (V)
What does Volt or Voltage mean? Voltage is the difference in electric potential between two places. It’s the unit for electrical potential difference. One volt (V) equals one joule per coulomb.
Think of volts as the power that ‘pushes’ electricity from the source to an endpoint. It can also be thought of like pressure. Both batteries and power circuits use voltage as a measure of electricity. Voltage can range from 1.5V to 110V, 120V or 208V.
Example Product Label:
INPUT 100-240VAC 8A MAX, 50-60HZ
OUTPUT 500W MAX +12V 44.5A MAX
Watt (W)
What is a Watt? A Watt, abbreviated (W), is a measure of the rate at which energy flows. It can be thought of as the actual amount of power that your electrical device uses. Watts are calculated by multiplying Volts x Amps = Watts.
For example, if you have a 208V/30A power circuit that is supplying the servers and networking gear in your rack, you have a total power capacity of 6,240W.
Example Product Label:
INPUT 100-240VAC 8A MAX, 50-60HZ
OUTPUT 500W MAX +12V 44.5A MAX
Kilowatt (kW)
What is a kilowatt? A Kilowatt, abbreviated (kW), is a globally recognized standard for measuring electricity. One kilowatt is equal to 1,000 watts. You can convert watts to kilowatts by dividing 1,000.
In the example above, the 208V/30A power circuit resulted in 6,240W. You can find the kilowatts by simply dividing by 1,000. In this case, 6,240/1,000 = 6.24kW.
kW is used to determine your total power draw or how much power your electrical devices require.
Kilowatt Hours (kWh)
What is a Kilowatt Hour? A Kilowatt Hour, abbreviated (kWh), is a measure of the number of kilowatts your electrical device uses over a certain time period. How many kW are your electrical devices consuming if they are powered on for an hour, two hours or 24 hours a day?
Kilowatt Hours (kWh) are used by utility companies to charge their customers for the power that they consume. The average cost of a kWh in the United States is $.139 cents per kWh.
For example, you have a server that requires 400W and it runs 24 hours. In a one day period, your server would consume 9,600W or 9.6kWh. If your utility costs are $.139 per kWh, your daily costs to run your server are $1.248 per day or $37.44 per month.
However, it’s important to note that this cost does not include the cost of cooling the data center for the heat produced by your server.
Kilovolt Amps (kVA)
What is Kilovolt Amp? A Kilovolt Amp, abbreviated as (kVA), is a measure of the apparent power in an electrical circuit. 1 kVA is equal to 1,000 volt-amps and are most commonly used for measuring power in generators and transformers.
Single Phase vs. Three Phase Power
What is single phase power? Single phase power supplies power through a single conductor. It’s less complex design, less expensive to implement and most efficient up to 1,000W. The max voltage for single phase is 230V.
What is three phase power? Three phase power flows through three conductors and has three distinct wave cycles. Three phase power has three or four wires. The max voltage for three phase is 415V.
Most data centers and colocation providers offer standard racks with single phase, AC power circuits. For high density colocation racks, some providers may offer three phase, AC power circuits.
Three phase power provides more efficient and higher power densities to colocation environments.
Megawatts (MW)
Last but not least is Megawatts. What is a Megawatt? A Megawatt is 1,000 kilowatts or 1,000,000 watts and is abbreviated as MW. In the data center industry, megawatts are reserved for wholesale colocation customers that require enough power for thousands of servers and related IT hardware.
For large wholesale colocation opportunities, costs are based on wholesale electricity rates plus a markup for the recapture of buildout costs, infrastructure, and cooling costs. Wholesale power costs for colocation can range from $.04 to $.09 cents per kWh. This is largely dependent on the provider, facility and geographic location.
