Energy Efficiency ResourcesEnergy Efficiency Resources

Most IT professionals need more fundamental knowledge of electrical power generation and distribution.

Electrical power costs will continue to rise. More IT systems and devices will be installed and almost all will operate continuously with no power-down time. The cost of electrical power can range from 8 cents/Kwh (kilowatt hour) to over 20 cents/Kwh. Some data centers have electrical bills that exceed $1 million per year. Controlling and reducing this energy cost is becoming more important every day for IT professionals, and many IT professionals are probably not electrical engineers. Most electrical engineers today studied electronics, not electrical power systems.

I am an electrical engineer who did study electrical power systems and distribution. My interest in energy efficiency has grown over the past few years. I have posted several blogs at NoJitter on energy issues:

* Energy Star Ratings; Some Not Real?
* The IP Phone Power Bill Can Be High
* Cisco's Energy Management Solution
* Data Center Density, Maxed Out?
* Green ICT Questions

Most IT professionals need more fundamental knowledge of electrical power generation and distribution. I have located very worthwhile documents that can act as references for IT professionals. Both documents can be found at an HP website.

The first document is the 44-page Power Basics for IT Professionals with mostly generic information. It is more of a book, not a document. It covers not only North American power distribution but Europe and Asia as well. The document begins with the basic terms, power generation, transmission and distribution with many useful diagrams.

One element of power usage that is not commonly known is "power factor" (page 14 in the document). The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power, and is a number between 0 and 1. You want the power factor to be greater than .95. If the power factor at the IT operation is too low and not readjusted by the enterprise, then the electrical utility will increase the power charges to the enterprise. The enterprise pays more for power because a lower power factor wastes energy.

Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load (IT equipment) and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power can be greater than the real power.

"Power factor correction" (PFC) is the process of adjusting the characteristics of electric loads in order to improve power factor so that it is closer to 1. Power factor correction can be installed by individual electrical customers to reduce the costs charged to them by their electrical utility. A good resource is Reducing Power Factor Cost by the U.S. Department of Energy.

The benefits of PFC are:

* The electrical utility bill is smaller.
* A high PF avoids the utility penalty that's assessed if the PF is below .95.
* The electrical system’s branch (connection) capacity will increase.
* It avoids voltage drops.
* It reduces overheating and increases reliability.

For those IT professionals that have to deal with servers, rack space, cabling and wiring, the Power Distribution section (page 17) will be very useful. The "Tools for powering the data center" has URLs for configuring devices and calculating their power consumption (page 25).

The appendices cover:

* U.S. design standards
* A complete list of the voltages and frequencies of the world
* Plug and socket types with pictures
* An extensive glossary of terms

The second document is the HP Power Advisor utility: a tool for estimating power requirements for HP ProLiant server systems, focusing on HP servers. Even though the document covers HP servers, a reader will learn enough elements that will prove useful no matter which vendor’s servers are in use. The document covers the HP Power Advisor calculator. At the end of this document, recommendations are provided for when to use and not use the calculator.

Both documents should be used as references. You can read them through, but they may make you sleepy.