This article originally appeared in the October 2008 issue of Internet Telephony magazine.
All power utility companies at one time or other suffer from service blackouts (no power), dropouts (very short blackouts), brownouts (lower voltage than normal), surges (higher voltage than normal) and phase shifts. Sometimes customers or their neighbors bring about their own electrical problems, such as blackouts (by overloading the local sub-station), brownouts (starting a large motor), phase shifts (using low power factor loads that require the power company to switch in power factor-correcting capacitors), voltage transients, and high frequency noise (such as from arc welding). Zeus up on Mount Olympus occasionally throws down a lightning bolt to a power line, resulting in a huge transient, and high winds can knock over power lines, creating blackouts. The solution to these problems? State-of-the-art Uninterruptible Power Supplies and power management.
The Uninterruptible Power Supply (UPS) is a device that sits between the mains power supply and the “loads” or devices drawing power, such as PCs, servers, routers, switches, appliances, and other electrical items. Most rely on a battery charger / rectifier, battery and inverter to supply power at appropriate moments, and offer power conditioning and sufficient back-up power to allow controlled shut-down of computer systems during outages.
UPS units can now be found in many homes, home offices and businesses, stationed next to PCs and routers. Call centers and data centers tend to use large rackmount units capable of supporting the power requirements of a series of servers, PCs and channel banks.
UPSs tend to fall into three categories: Off-line, line-interactive and on-line. An off-line UPS, or “standby UPS” is an inexpensive device typically used to protect single-user workstations and less critical applications. You plug an off-line UPS into an AC outlet. A switch that senses a power cut. The load is usually connected directly to the mains, and power protection occurs only when line voltage decays enough to be considered an outage, whereupon DC power is drawn from the batteries and the inverter converts the DC back into AC Power that your system needs. Off-line UPSs typically offer surge suppression, too. The time it takes to transfer from your power source to the UPS’s batteries can range from two and four milliseconds.
The more advanced line-interactive UPS is basically an off-line UPS with power conditioning enhancements. They can increase voltage coming from your AC power supply and suppress line noise. Line-interactive UPSs don’t immediately switch over to the battery when AC voltage decreases. Instead, they keep the voltage within a certain range, say 10 to 15 percent above or below the voltage you need. Their transfer time is also about two to four milliseconds.
The most costly and advanced system is the On-line UPSs. It’s inverter supplies all of the load all of the time. They don’t require separate battery power because they continually recharge themselves. They continuously convert incoming AC supply to DC current, and smooth out any noise, overvoltage or undervoltage. They then change the now pristine DC current back into AC, thereby regenerating the mains sinusoidal waveform. This “double conversion” process is the perhaps best form of power conditioning, since you end up with a perfect sinusoidal voltage waveform and the UPS can fully protect the computer load.
Power Ratings: VA and Watts
Many people become confused when judging UPS power capacity. The average UPS is rated not in Watts, but in Volt-Amps, or VA, the amount of apparent power supplied to equipment, or volts x amps. You were doubtless taught in school that Watts = Volts x Amps, so you might jump to the conclusion that VA = Watts. Actually, wattage is the actual amount of power available to do work, and is always less than or equal to the VA rating when it comes to PCs and electric motors, because VA = Watts / the “Power Factor”. Where reactive loads are present, such as with devices having capacitors or inductors, energy storage in the loads result in a time difference between the current and voltage waveforms. This stored energy returns to the source and isn’t available to do work at the load. The ratio of Watts to VA is the equipment’s “power factor”, which is a number between zero and one. A circuit with a low power factor will need higher currents to transfer a given quantity of real power than a circuit with a high power factor. Devices based on delicate and electronic components such as those containing transformers and capacitors have a Power Factor of less than one, such as 0.5 or 0.6. Thus, a computer may need 160VA to run correctly and if it’s rated at 80 Watts, then the Power Factor is 80 / 160 = 0.5. Since VA = Watts / Power Factor, then Watts = VA x Power Factor. Seeing that your PC’s is rated at 80 Watts, you might run to a store and accidentally buy an 80 VA UPS. That’s a bad idea. Since Watts = VA x Power Factor, you must realize that 80 Watts = 160VA x 0.5 for our imaginary computer. This means that you actually need a 160VA unit to protect and supply power for an 80 Watt computer.
Moral of the story: even if you’re confident you’ve determined what the proper capacity of your UPS should be, be sure to add at least another 20 percent capacity for good measure.
With modern power management, the user is notified immediately of the status of the equipment (via a phone call, over the Internet or in some other fashion) and can control the power supply remotely and manage the electrical equipment. Many systems have automatic shutdown if they sense a lack of power.
Active Power
Active Power’s CleanSource (News - Alert) AC product line is rated for both 60 Hz and 50 Hz applications, and provides enough power to ride through transients and allows time to bridge to a generator. CleanSource is offered in a 130-3600 kVA system range. They sport up to 98 percent energy efficiency, and can be configured in multi-megawatt turnkey solutions.
CleanSource is a fascinating company, because it offers products that don’t rely on conventional chemical batteries.
For example, the CleanSource DC product line stores energy in a spinning flywheel. Compatible with major UPS brands, CleanSource DC can be used in conjunction with a standby-generator to enable a continuous power solution, or as a standalone with a UPS for optimal power protection. CleanSource DC can also supplement or replace battery strings in existing UPS installations. CleanSource DC is sold and serviced directly through Active Power, and through strategic partners worldwide.
On the other hand, Active Power’s CoolAir DC stores energy in the form of compressed air and heat. When the electrical utility fails, compressed air is routed through a Thermal Storage Unit (TSU) to acquire heat energy. The heated air spins a simple turbine/alternator to produce electric power. The CoolAir DC also contains a small, continuous-duty flywheel to support the critical load during the brief period required for the turbine to spin up to speed.
American Power Conversion (APC (News - Alert))
APC offers an immense line of UPS devices (Yours Truly even uses three of them in his home office) for SOHOs, SMBs, enterprises, data centers, service providers, and so forth. They also offer power distribution systems (Stationary Power Distribution Units [PDUs], Rack PDUs, and Rack Automatic Transfer Switches), surge protection and power conditioning devices, cables, network accessories, and a range of customer services.
APC has also perfected UPS Management solutions designed to control and monitor UPSs from desktop to data center. In the event of an extended power outage, an automated server shutdown can take place. APC’s Physical Security and Environmental solutions not only perform environmental monitoring, but also access control and video surveillance of your computing environment, however big or small it may be. APC’s Physical Infrastructure Management solutions enable you to operate and monitor both APC and third party devices and include intelligent ITIL-based software applications to maximize utilization of your existing data center capacity.
CyberPower Systems
CyberPower Systems has given the UPS the “Green” treatment, having developed technology that reduces energy costs and consumption. Called GreenPower UPS technology, CyberPower’s design improves energy efficiency by reducing energy consumption during normal utility power operation by up to 75 percent compared to conventional UPS systems. During normal power mode the GreenPower UPS design bypasses the Automatic Voltage Regulation (AVR) and the transformer, thus significantly reducing the energy used and heat generated by the transformer during normal mode.
“Our competitors’ UPS systems have a significantly lower level of energy-efficiency, especially when the UPS design is conventional online double-conversion, or line interactive and running under full load,” says Michael Ho, President of Manufacturing for CyberPower Systems.
Eaton (News - Alert) / Powerware
Eaton offers Powerware UPS (uninterruptible power supply) products as part of their PowerChain Management solutions portfolio. Powerware solutions include UPSs ranging from 300 VA to more than 4,000 kVA as well as DC Power Systems. They also offer various software and connectivity devices that enable you to to proactively manage your systems, from basic monitoring and shutdown to predictive analysis and power management. Moreover, Powerware Integration Services offers complete solutions tailored for the specific requirements of federal, telecom, and commercial markets. Powerware solutions are backed with 7x24 service support.
Eaton has reached this point by having combined the research, innovation and expertise of several well-known brands, such as Powerware, MGE Office Protection Systems and Santak. Recently, Eaton unveil two new Powerware UPSs, the Eaton 9130 and 5130 UPSs. The 9130 is an online double-conversion UPS that operates at 95 percent efficiency. The 5130 is a highly flexible 1250 to 3000 VA line-interactive UPSs, is very compact and is thus suitable for dense rack enclosures.
Additionally, Eaton’s power management software products are now cross-compatible with its Powerware, MGE Office Protection Systems, Aphel and Pulizzi product families.
Emerson (News - Alert) Network Power
Emerson Network Power offers an enormous portfolio of solutions involving their Business-Critical Continuity™ initiative: AC Power, connectivity, DC power, embedded computing, embedded power, racks/integrated cabinets, monitoring, outside plant equipment, power switching/controls, precision cooling, services and surge protection.
Emerson also recently introduced Energy Logic for Telecommunications, a series of 12 sequential strategies they’ve formulated that can be used to reduce energy consumption across the network. The key is eliminating inefficiencies along the energy path, triggering cascading benefits by avoiding associated losses upstream. The potential efficiency gains through Energy Logic for Telecommunications are significant, reducing consumption by nearly 60 percent at wireless sites and 40 percent at the central office. This is considerable when one considers that the telecom industry is estimated to be responsible for about 1 percent of the world’s energy consumption last year. That equates to 15 million U.S. homes and matches the CO2 emissions of 29 million cars.
Para Systems / Minuteman
Para Systems, Inc. is a major provider of power protection and management products including the venerable Minuteman® UPSs for computers, voice and data communication system and other mission-critical equipment. Minuteman UPS products are available from 325VA to 10kVA. They come in all three categories: Standby, line-interactive, and on-line systems. They also offer Power Distribution Unit (PDU) systems, Keyboard-Video-Mouse (KVM) systems, and surge suppressors.
Recently the company debuted the Minuteman EnterprisePlus Line-Interactive UPS system, having voltage regulation, spike and surge protection and battery backup. The EnterprisePlus Line Interactive UPS series has five 120 VAC models and two 208 VAC models, ranging from the E750RM2U UPS rated at 750VA/600W — 120VAC with 6 UPS outlets, to the E3000RM2U UPS rated at 3000VA/2560W — both 120VAC and 208VAC with 7 UPS outlets.
The Minuteman EnterprisePlus line-interactive UPS occupies only 2U of space in a traditional rack. It’s quite efficient, with a 0.8 power factor that increases the capacity of the unit without the need to migrate to larger models (0.88 power factor for 2000VA and 0.853 power factor for 3000VA). The units also support “load shedding”, which extends the time of critical applications without adding external battery packs by removing power to non-essential devices connected to the same UPS through the network connections. The Minuteman EnterprisePlus independent battery bypass — allows the UPS to provide voltage regulation with surge and spike protection on the utility AC power even when batteries are weak or dead.
Tripp Lite (News - Alert)
Chicago-based Tripp Lite is said to have long ago devised the world’s first UPS system specifically for PCs, and 15 million units of its long-renowned premium surge suppressor — the Isobar — are in use. Tripp Lite offers a dizzying array of more than 1000 different products, including UPS systems, surge suppressors, inverters, KVM switches, cables and connectivity products, power strips and PDUs, notebook accessories, rack systems, network management accessories and more. Headquartered in Chicago, Illinois, Tripp Lite maintains a global presence with fully staffed offices worldwide.
Recently Tripp Lite released a new version of its free PowerAlert software, part of the PowerAlert Network Management System, consisting of three specialized components that combine to deliver full-featured power management capabilities from desktops to the enterprise. The system enables network managers to monitor and control up to 250 UPS systems and PDUs through a single interface. PowerAlert Local allows end users to monitor and control UPS systems connected to a host computer through a USB or serial cable. It also includes an SNMP agent so that UPS systems can be discovered and managed by PowerAlert Network Management System or a third-party network management system. Thus, instead of having a UPS system communicate with a PC through a USB or serial cable, PowerAlert Local running on the computer enables the end user to monitor power conditions and control the UPS system with a console interface. PowerAlert Local also directs the computer to automatically perform user-defined actions in response to changes in UPS and power conditions. For example, the computer can save open files and shut down safely when the UPS system’s battery is about to be depleted during a long power failure.
PowerAlert Network Shutdown Agent is the component that allows the host computer to monitor a designated PowerAlert Local client or SNMPWEBCARD accessory over the network. When a selected power event is detected — typically an “on battery” event — the host computer automatically hibernates or shuts down after a user-specified delay. It targets computers having restricted system resources or that cannot connect to a UPS system through a USB or serial cable.
What Are You Waiting For?
Power protection is perhaps the cheapest form of system “insurance” you can buy. The technology is solid and has proven itself over decades of research and development. You can protect PC and appliance hardware with an added cost of about 10 percent to 25 percent of the hardware’s value. Of course, that doesn’t include the value of the data, which these days could theoretically exceed the value of all of the equipment you own. Also, keep in mind that even the best power technology has its limitations – you may have a problem if lightning scores a direct hit on your local power line.
Companies Mentioned in this Article:
Active Power
American Power Conversion
CyberPower Systems
Eaton / Powerware
Emerson Network Power
Para Systems / Minuteman
Tripp Lite
Richard Grigonis is Executive Editor of TMC�s IP Communications Group. To read more of Richard�s articles, please visit his columnist page.
Edited by Greg Galitzine
Internet Telephony Magazine
Click here to read latest issue
CUSTOMER 
Cloud Computing Magazine
Click here to read latest issue
IoT EVOLUTION MAGAZINE
