This tutorial was first published in Electronic Products magazine (http://www.electronicproducts.com) and has been updated in 2017. The True Cost of UPS and Batteries Tutorial Engineering Department Falcon Electric, Inc. www.FalconUPS.com ©2017 Falcon Electric, Inc. All Rights Reserved 2 Introduction The following is a brief discussion of the present day state of uninterruptible power supplies (UPS) under 10kVA, the largest UPS market segment, and their battery technology. They make up the bulk of the UPS units installed worldwide for business, industrial, scientific, IT and home applications. Since the UPS market is very large, the UPS business has become very competitive, with a large number of domestic and international UPS manufacturers to choose from. Unfortunately, the selection is so large that users are often misled into buying a UPS on price alone, without fully considering available options or understanding what they are buying. For home users this is typically not a problem, as they simply want to backup their home computer long enough to allow the operating system to perform an orderly shutdown. For the other applications referenced, users face a costly learning experience if they buy a UPS on cost alone. Before considering the purchase of a UPS, the consumer must know the following: Types of UPS Designs 1. There are three basic UPS designs: standby (also known as “offline”), line-interactive and online. They provide three different levels of backup and power protection. The Standby (or “Offline”) UPS: The standby UPS offers low-level power protection and battery backup. Through this type of UPS, the equipment is connected directly to incoming utility power with the same voltage transient clamping devices used in a common surge protected plug strip. When the incoming utility voltage falls below a predetermined level, the UPS turns on its internal DC-AC inverter circuitry, which is powered from an internal storage battery. The UPS then mechanically switches the connected equipment onto its DC-AC inverter output. The switchover time is stated by most manufacturers as being very short, however, the transition time has shown to be much longer, causing a brief power interruption. When it switches to its internal DC-AC inverter, it may only provide a square wave, modified square wave or quasi-sinewave, not a pure sinewave. This means the equipment is not receiving quality power and will only provide short periods of battery backup time. 3 The Line-interactive UPS: The line-interactive UPS offers moderate power protection and battery backup as the standby, except it has the added feature of minimal voltage regulation while the UPS is operating from the utility source. This UPS design came about due to the standby UPS’s inability to provide an acceptable output voltage to the connected equipment during “brownout” conditions. A “brownout” happens when the utility voltage remains excessively low for a sustained period. Under these conditions the standby UPS would go to battery operation and if the brownout was sustained long enough, the UPS battery would become fully discharged, turn the power off to the connected equipment and not be able to be turned back on until the utility voltage returned to normal. To prevent this from happening, a voltage regulating transformer was added, hence the term “line-interactive.” This feature really does help as low voltage utility conditions are common. The down side of this design is that the majority of line-interactive UPSs must switch to battery momentarily when making transformer voltage adjustments and yielding a wider output voltage regulation. The Online UPS: The online UPS (which Falcon Electric manufactures) provides the highest level of power protection for critical applications. It is the best choice for use in any medium to large business, industrial, IT, military or scientific application. The true advantage to the online UPS is its ability to provide an electrical firewall between the incoming utility power and sensitive electronic equipment. While the standby and line-interactive designs leave equipment connected directly to the utility power with minimal surge protection, the online UPS provides an electronic layer of protection from common power quality problems. This is accomplished inside the UPS in several tiers of circuits. First, the incoming AC utility voltage is passed through surge protected rectifier stage where it is converter to a Direct Current (DC) and is heavily filtered by large capacitors. This tier removes line noise, high voltage transients, harmonic distortion and frequency related problems. The battery is also connected to this tier and takes over as the energy source in the event of a utility loss. This makes the transition between utility and battery power seamless, without an interruption. The Pulse Width Modulation (PWM) inverter regenerates new, tightly regulated reliable output power. As the online UPS incorporates a continuous duty inverter, it supports the connection of extended runtime battery packs, allowing runtimes from several minutes to several hours. 4 Falcon's SSG and SSG-RP Online Industrial UPS families Furthermore, industrial online UPS models, like Falcon’s SSG and SSG-RP UPS families, are available for industrial settings since they are in demanding and/or rugged environments. Industrial- grade online UPSs are specifically designed to meet the rigors of these environments which may include wide operating temperatures of -20°C to 55°C (-4°F to 131°F). Battery and Maintenance Costs: A Real World Example As a real world example, with the average UPS using from three to twenty Valve Regulated Lead-Acid (VRLA) batteries, a toll road company in Southwestern U.S. would need many UPS units installed in toll booths, resulting in an exceedingly high cost of ownership. The same is true for all types of production applications, where hundreds of UPSs are deployed. The cost of the batteries, combined with the manpower to change them every other year, becomes a drain on resources. The VRLA battery service life can be shortened further by excessive discharge and recharge cycles. Standby and line-interactive UPS models can excessively switch to battery mode if installed in locations where utility voltage or frequency regulation is poor. This is not the case with double-conversion online UPS models as they only draw power from the batteries when the utility voltage is excessively low, or is lost completely. Furthermore, the battery chargers incorporated into industrial online UPSs are of a better design and better maintain the batteries charge state, resulting in a longer service life. New Generation of Industrial UPS and 10 to 12-Year Battery Ratings VRLA battery technology is advancing, so look for a UPS company that offers industrial-grade products using batteries having a higher temperature rating and up to a 10 to 12-year service life. Not only do these batteries reduce the number of battery replacements when installed into a 25°C (77°F) environment, but per manufacturer specifications, the batteries will have a 4-year service life when used in a 50°C (122°F) environment. A standard battery lasts less than a year at that temperature. These batteries are ideal for high temperature applications. 5 A few UPS manufacturers have taken implementation of these batteries one step further by thermally insulating them inside of a thick wall plastic enclosure. This thermally insulates the batteries, adding to their service life. The inside of enclosed equipment racks are often packed with heat generating equipment which can raise the internal temperature of the rack to very high levels. In most rackmount UPS installations, the internal UPS batteries are secured directly against the bottom surface of the UPS chassis. As the internal rack temperature increases, it elevates the temperature of the metal chassis surfaces, which is then conducted directly to the internal batteries, reducing their service life. 3 to 5-Year Rated Batteries 10 to12-Year Rated Batteries Proper UPS Storage Proper UPS storage is another factor that can affect battery life. When the UPS is disconnected and not used for several months, the internal VRLA batteries will self-discharge. If stored for over six months, they can become overly discharged to the point they cannot be recharged again, requiring a premature battery replacement. It is a good practice when storing a UPS to plug it in and recharge the batteries periodically to prevent this problem. The storage temperature also has an impact on overall service life. If the batteries are stored at higher temperatures, frequent recharging will be required to maintain maximum battery service life. Lastly, when replacing VRLA batteries, always dispose or recycle the spent batteries in accordance with all local and federal laws and regulations. VRLA batteries are classified as hazardous waste, but the good news is they can be almost entirely recycled. 6 Conclusion With the microprocessor controlling virtually every computer and piece of today’s electronic equipment, selecting an online UPS assures the highest level performance and protects against the greatest number of potential power problems. This assures a successful integration even with the most power sensitive equipment. It also provides reliable, worry-free equipment operation and eliminates costly trial and error approaches. ©2017 Falcon Electric, Inc. All rights reserved. Falcon Electric, Inc. Proprietary Proprietary: The information contained herein is proprietary to Falcon Electric, Inc. and shall not be reproduced or disclosed in whole or in part or used for any reason except when such user possesses direct, written authorization from Falcon Electric, Inc. The statements contained herein are based on good faith assumptions and provided for general information purposes only. These statements do not constitute an offer, promise, warranty or guarantee of performance. Actual results may vary depending on certain events or conditions. This document should not be used or relied upon for any purpose other than that intended by Falcon Electric, Inc.