Finally, the article says that since energy flows through transformers, converting MV AC power to 120V or 208V for server racks, the data center loses eight to nine percent of its energy. Also, each server needs to make an AC-to-DC conversion for its processors, memory, storage, which generates additional losses. These losses have led some experts to propose distributing DC power throughout the data center, which they say can cut losses by five to 20 percent.

Industry News
Staco Energy Products, T&B Form UPS Maintenance Partnership
Staco Energy Products recently announcd that Thomas & Betts (T&B) Global Services will now provide service and support for Staco's entire FirstLine® 3-phase UPS line-up.

In addition to start-up and commissioning services, T&B Global Services will also provide preventive maintenance, 24/7 emergency repair, and both standard and extended warranty program administration.

Ask The Expert
Get Answers To Your PQ Questions
Here's your chance to get answers to your PQ questions. E-mail your question to John DeDad at john.dedad@penton.com, and we'll pose it to our faculty of power quality experts. The answer will be published in the next earliest scheduled issue of PQNewsBeat.

Question: I’m currently working as a power quality engineer for a local electric utility and recently visited two schools in our service territory. They are both served distribution voltage 12,470V from different substations. Both of them are complaining about the same issue: computer power supplies burning up. One school has its computers plugged into small UPS units while the other doesn’t have any UPS units. Whatever variations that occur on the distribution system have an effect on the computers. Do you have any possible solutions to these problems or have you run across something similar in your power quality studies?

Answer by John DeDad, EC&M Magazine: You mentioned that one school has its PC’s plugged into desktop UPS units. If the batteries in these units are bad or if the UPS units are defective, the PC’s can be affected by reduced or increased input voltage.

Here’s what happens during voltage sags: While trying to maintain constant DC output as the line voltage declines, the DC-to-DC converter circuit of the power supply has to draw from its reservoir capacitor. With line voltage reduced, this capacitor experiences deep discharges between the twice-per-cycle charging periods. Electrolytic capacitors aren't designed for deep discharge — and they're not designed for the resulting large terminal variations. So, the excessive capacitor charge and discharge currents cause internal heat dissipation, which produces dielectric stress. This condition results in reduced mean time between failures (MTBF). In addition, rectifiers and DC-to-DC converter switching transistors draw high-peak currents, which raise their junction temperatures. These temperature excursions take a toll on semiconductor longevity.

Here’s what happens during voltage surges: Short-term voltage surges (10% beyond nominal) aren't usually harmful. However, higher input voltages can overwhelm the voltage regulating ability. The result is damaging voltage levels fed to the electronic circuits. High input voltage can also puncture a power supply's rectifier and switching transistor junctions, causing MTBF reduction and eventual breakdown. High-voltage transients lasting microseconds can permanently wreck the power supply and its electronic equipment load.

My guess, based on the limited information you provided, is that the UPS units are NOT working and the connected PCs are being affected by either voltage sags or surges. These sags and/or surges are also affecting the PCs that are NOT connected to UPS units.

I would try logging the voltage at both schools to verify the extent of any volatge sags or surges. Also, have the school maintenance people look at the desktop UPS units to verify performance and battery integrity.

New Products & Services
Automatic Transfer Switches
GE Digital Energy recently introduced its Zenith ZTE Series 40A-4000A Automatic Transfer Switch (ATS) system, which offers expanded diagnostics, built-in test and outage reporting, power quality metering, and high-speed alarm capture capability. Also included are built-in serial and Ethernet networking and user-configurable alarms. Data log and waveform files may be viewed and saved using free MX350 Setup™. Also included is Auto Load Shed, which permits the ATS to signal for the disconnection of downstream lower-priority loads in the event of a generator overload, and built-in power quality metering for measuring current and voltage harmonics/THD. The ZTE may be custom programmed using GE's FlexLogic™. For more information, go to
www.gedigitalenergy.com/zte

Maintenance Bypass Switch
Staco Energy Products recently introduced its FirstLine wall-mounted maintenance bypass switch (MBS), which features make-before-break interlocking technology and is available in 208VAC and 480VAC configurations. The MBS provides a safe means of removing a UPS from the circuit while maintaining connection between the load and the utility. According to the company, the interlock ensures the switch is closed and opened in proper sequence to avoid improper application of power to the system or load. For more information, go to www.stacoenergy.com/firstlineups.htm.

Voltage Monitor
ICM Controls recently introduced its ICM492 digital line voltage monitor for single-phase equipment, which continuously checks incoming line voltage for faults and displays RMS voltage on its backlit digital display. Adjustable over- and undervoltage settings establish boundaries for safe operation of equipment. Also, fault condition response times can be fine-tuned to reduce nuisance tripping. Additional features include adjustable anti-short-cycle time delay, universal line voltage input, and heavy-duty SPDT relay output. For more information, go to icmcontrols.com.

Shows & Events




Data Center Energy Efficiency Seminars
Emerson Network Power and Digital Realty Trust are teaming up for a five-stop global tour to educate data center professionals about energy efficiency-related cooling and measurement tactics that save businesses money.

The free, one-day seminars will feature executives from both companies and are designed for data center decision makers, operational personnel, and consulting and mechanical engineers. Presentations will focus on prioritization of cost-saving decisions about energy use and critical resource constraints without compromising data center availability or flexibility. Specific dates and locations include New York City (March 3), Dallas (March 5), London (April 21), Paris (May 26), and San Francisco (July 16).

Attendees will learn how to achieve quantifiable savings and return on their technology investments by incorporating new technologies and best practices. As part of the program, attendees will also hear about:

• Cascading effects of operating efficiencies and how to harness their impact
• Techniques for improved energy usage measurement
• Best practices of airflow management
• Effects of proper variable speed drive utilization
• Methods for close-coupled cooling and air containment
• Monitoring and control of key performance indicators for efficiency and reliability

To register, go to www.digitalrealtytrust.com/cooling.



PEARL Electrical Safety and Reliability Conference
The 12th Electrical Safety and Reliability Conference & Exhibition will take place on April 18-20, 2009 at the Hyatt Regency Atlanta in Atlanta, Ga. Sponsored by the Professional Electrical Apparatus Recyclers League (PEARL), this event will have nationwide participation by professionals concerned with the safety and reliability of remanufactured and recycled electrical equipment and apparatus. Conference topics will include:

• Anti-Counterfeiting Measures
• Economic Preparedness
• Green Initiatives
• Low Voltage Motor Control Training
• Project Management
• Remanufacturing Methodologies
• Safety Standards

For an updated agenda and on-line registration, go to www.pearl1.org.