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Chapter 11 Power Conditioners and Uninterruptible Power Supplies • Becoming more of a concern as utility de-regulation proceeds Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-1 Distortion in the Input Voltage • The voltage supplied by the utility may not be sinusoidal Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-2 Typical Voltage Tolerance Envelope for Computer Systems • This has been superceded by a more recent standard Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-3 Typical Range of Input Power Quality Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-4 Electronic Tap Changers • Controls voltage magnitude by connecting the output to the appropriate transformer tap Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-5 Uninterruptible Power Supplies (UPS) • Block diagram; energy storage is shown to be in batteries but other means are being investigated Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-6 UPS: Possible Rectifier Arrangements • The input normally supplies power to the load as well as charges the battery bank Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-7 UPS: Another Possible Rectifier Arrangement • Consists of a high-frequency isolation transformer Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-8 UPS: Another Possible Input Arrangement • A separate small battery charger circuit Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-9 Battery Charging Waveforms as Function of Time • Initially, a discharged battery is charged with a constant current Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-10 UPS: Various Inverter Arrangements • Depends on applications, power ratings Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-11 UPS: Control • Typically the load is highly nonlinear and the voltage output of the UPS must be as close to the desired sinusoidal reference as possible Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-12 UPS Supplying Several Loads • With higher power UPS supplying several loads, malfunction within one load should not disturb the other loads Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-13 Another Possible UPS Arrangement • Functions of battery charging and the inverter are combined Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-14 UPS: Using the Line Voltage as Backup • Needs static transfer switches Copyright © 2003 by John Wiley & Sons, Inc. Chapter 11 Power Conditioners and UPS 11-15