UNINTERRUPTIBLE POWER SUPPLIES JOHN LIGUORI CONSULTING ENGINEER MSEE

UNINTERRUPTIBLE POWER SUPPLIES JOHN LIGUORI CONSULTING ENGINEER MSEE, PE PRESENTED TO THE IEEE LONG ISLAND CONSULTANT’S NETWORK 9/6/06 1

UNINTERRUPTIBLE POWER SUPPLIES • THIS PRESENTATION IS FOR INFORMATIONAL AND EDUCATIONAL PURPOSES ONLY. IT DOES NOT CONTAIN ALL INFORMATION REQUIRED, AND IS NOT INTENDED TO BE USED FOR THE SPECIFICATION OR DESIGN OF UNINTERRUPTIBLE POWER SUPPLIES (UPS) OR UPS SYSTEMS. 2

UNINTERRUPTIBLE POWER SUPPLIES OUTLINE • • INTRODUCTION POWER DISTURBANCES UNINTERRUPTIBLE POWER SUPPLIES GENERAL DISCUSSION SUMMARY REFERENCES QUESTIONS 3

INTRODUCTION • PURPOSE • WHAT IS AN UNINTERRUPTIBLE POWER SUPPLY? • WHY USE A UPS? 4

PURPOSE • THE PURPOSE OF THIS PRESENTATION IS TO DISCUSS THE DIFFERENT TYPES OF UNINTERRUPTIBLE POWER SUPPLIES AVAILABLE, WHAT THE UPS PROTECTS AGAINST, THE COMPONENTS OF A UPS, AND ISSUES REGARDING SELECTION AND SIZING. • THE DIFFERENT TYPES AND CAUSES OF POWER DISTURBANCES ARE DISCUSSED, AS WELL AS WHAT THE POWER UTILITY, THE ORIGINAL EQUIPMENT MANUFACTURER, AND YOU, CAN DO TO MINIMIZE THEIR EFFECT. 5

WHAT IS AN UNINTERRUPTIBLE POWER SUPPLY? • AN UNINTERRUPTIBLE POWER SUPPLY (UPS) IS A DEVICE THAT HAS AN ALTERNATE SOURCE OF ENERGY THAT CAN PROVIDE POWER WHEN THE PRIMARY POWER SOURCE IS TEMPORARILY DISABLED • THE SWITCHOVER TIME MUST BE SMALL ENOUGH TO NOT CAUSE A DISRUPTION IN THE OPERATION OF THE LOADS 6

WHY USE A UPS? • PROTECTS AGAINST MULTIPLE TYPES OF POWER DISTURBANCES • ONLY DEVICE THAT PROTECTS AGAINST AN OUTAGE • OFFERS PROTECTION AGAINST Ø EQUIPMENT NOT OPERATING PROPERLY Ø COMPUTER AND EQUIPMENT DAMAGE Ø DATA LOSS Ø TIME AND EXPENSE TO RECOVER BACK TO WHERE YOU WERE, IF EVEN POSSIBLE 7

POWER DISTURBANCES • • CAUSES TYPES DURATION RESULTING PROBLEMS COMMENTS WHAT THE POWER UTILITY CAN DO WHAT THE ORIGINAL EQUIPMENT MANUFACTURER (OEM) CAN DO • WHAT YOU CAN DO • PROTECTIVE DEVICES 8

CAUSES OF POWER DISTURBANCES • STORM ACTIVITY – LIGHTNING, WIND, ICE • OBJECTS COMING IN CONTACT WITH POWER LINE AND TRIPPING BREAKER – TREE BRANCHES, ANIMALS, OTHER • UTILITY FAULT CLEARING • CONSTRUCTION ACTIVITY • ACCIDENTS – MOTOR VEHICLE, OTHER • EQUIPMENT FAILURE • OVERLOADING • LOAD SWITCHING • NON-LINEAR LOADS • POOR GROUNDING • ESD 9

TYPES OF POWER DISTURBANCES • • • INTERRUPTION SAG, UNDER VOLTAGE SURGE, OVER VOLTAGE FLUCTUATION FREQUENCY VARIATION SPIKES / TRANSIENTS Ø IMPULSIVE Ø OSCILLATORY • WAVEFORM DISTORTION Ø Ø Ø DC OFFSET HARMONICS INTERHARMONICS NOTCHING NOISE • VOLTAGE IMBALANCE 10

DURATION OF POWER DISTURBANCES • • INSTANTANEOUS MOMENTARY TEMPORARY SUSTAINED - ½ CYCLE (8 1/3 ms) OR LESS ½ CYCLE TO 3 SEC TO 1 MIN GREATER THAN 1 MINUTE 11

CLASSIFICATION OF PROBLEMS RESULTING FROM POWER DISTURBANCES • DISRUPTIVE Ø EQUIPMENT DOES NOT OPERATE AS INTENDED • DISSIPATIVE Ø EQUIPMENT EXPERIENCES REPEATED STRESSES THAT LEAD TO FAILURE LATER FOR NO APPARENT REASON • DESTRUCTIVE Ø EQUIPMENT FAILS AT THE INSTANT THE DISTURBANCE OCCURS 12

PROBLEMS RESULTING FROM POWER DISTURBANCES • • DATA ERRORS DATA LOSS BLOWN FUSES TRIPPED BREAKERS INTERFERENCE WITH CONTROL OF LOADS OVERLOADED NEUTRAL CONDUCTORS MOTORS Ø Ø Ø • HEATING SPEED VARIATION STALLING AUDIBLE NOISE VIBRATION TRANSFORMERS Ø HEATING Ø AUDIBLE NOISE Ø VIBRATION 13

POWER DISTURBANCES - COMMENTS • NOT ONLY IS MODERN EQUIPMENT MORE SUSCEPTIBLE TO POWER DISTURBANCES, BUT THE EQUIPMENT ITSELF GENERATES MORE DISTURBANCES • ALL LOADS, FROM LARGE POWERFULL MOTORS AND INDUSTRIAL EQUIPMENT TO SMALL, SENSITIVE ELECTRONIC COMPONENTS, ARE CONNECTED TO THE SAME POWER GRID 14

WHAT THE POWER UTILITY CAN DO TO MINIMIZE THE EFFECT OF POWER DISTURBANCES • INSTALL STORM RESISTANT WIRING • USE INFRA RED SCANNING TO DETECT WEAK SPOTS IN POWER LINES • INSTALL REMOTE CONTROLLED RADIO SWITCHES TO RESTORE POWER QUICKLY • CLEAR TREE LIMBS AWAY FROM POWER LINES 15

WHAT THE OEM CAN DO TO MINIMIZE THE EFFECT OF POWER DISTURBANCES BUILD EQUIPMENT CONTAINING ONE OR MORE INTERNAL PROTECTIVE DEVICES Ø Ø SURGE PROTECTIVE DEVICES LINE FILTERS ISOLATION TRANSFORMER BATTERY OR CAPACITOR BACK UP TO INCREASE RIDE THROUGH TIME 16

WHAT YOU CAN DO TO MINIMIZE THE EFFECT OF POWER DISTURBANCES • BUY EQUIPMENT THAT HAS INTERNAL PROTECTIVE DEVICES Ø FOR EXAMPLE, BATTERY BACK UP FOR ANY APPLIANCE THAT CONTAINS A CLOCK • USE ONE OR MORE EXTERNAL PROTECTIVE DEVICES Ø Ø Ø SURGE PROTECTORS LINE FILTERS ISOLATION TRANSFORMER VOLTAGE REGULATING LINE CONDITIONER UPS 17

PROTECTIVE DEVICES OTHER THAN UPS • SURGE PROTECTIVE DEVICES – SPD’S PROTECTS AGAINST SPIKES OF LIMITED ENERGY Ø METAL OXIDE VARISTORS – MOV Ø DIODES Ø GAS TUBES Ø LCR FILTERS Ø HYBRIDS • LINE FILTERS OUT HARMONICS, TRANSIENTS AND NOISE • ISOLATION TRANSFORMER ELIMINATES DC OFFSET AND NOISE • VOLTAGE REGULATING LINE CONDITIONER AUTOMATICALLY ADJUSTS FOR UNDER AND OVER VOLTAGES Ø CONSTANT VOLTAGE TRANSFORMER - CVT Ø MOTORIZED VARIAC 18

POWER DISTURBANCES AND PROTECTIVE DEVICES 19

UPS • • ARCHITECTURES WAVEFORMS INVERTER TECHNOLOGY COMPONENTS SWITCHOVER TIME ADVANTAGES / DIS-ADVANTAGES SIZING BATTERY SAFETY 20

UPS ARCHITECTURES • LINE INTERACTIVE • ON-LINE 21

BLOCK DIAGRAM LINE INTERACTIVE UPS AUTOMATIC SWITCH AC SUPPLY BATTERY CHARGER CRITICAL LOAD (AC) INVERTER DC TO AC BATTERY AC FAIL 22

BLOCK DIAGRAM ON-LINE UPS AUTOMATIC SWITCH AC SUPPLY CONVERTER AC TO DC INVERTER DC TO AC CRITICAL LOAD (AC) BATTERY INVERTER FAIL 23

BLOCK DIAGRAM LAPTOP COMPUTER POWER SUPPLY CRITICAL LOAD AC SUPPLY CONVERTER AC TO DC CONVERTER DC TO DC (DC) BATTERY 24

UPS WAVEFORMS • TRUE SINEWAVE • MODIFIED SINEWAVE • SQUARE WAVE 25

UPS WAVEFORMS 26

INVERTER TECHNOLOGY FOR TRUE SINEWAVE • PULSE WIDTH MODULATION - PWM • LINEAR AMPLIFIER • RESONANT INVERTER 27

BLOCK DIAGRAM PWM INVERTER DC POWER HIGH FREQUENCY GENERATOR PULSE WIDTH MODULATOR BASE / GATE DRIVE COMPARISON AMPLIFIER TRANSISTOR BRIDGE TRANSFORMER FILTER CRITICAL LOAD (AC) REFERENCE SINEWAVE GENERATOR 28

BLOCK DIAGRAM LINEAR AMPLIFER INVERTER DC POWER SINEWAVE OSCILLATOR TRANSFORMER CRITICAL LOAD (AC) OSCILLATOR AMPLIFIER COMPARISON AMPLIFIER POWER AMPLIFIER 29

BLOCK DIAGRAM RESONANT INVERTER DC POWER SQUARE WAVE GENERATOR SWITCH DRIVE TRANSISTOR SWITCHES TRANSFORMER LC RESONANT TANK FILTER CRITICAL LOAD (AC) (OR FERRORESONANT) 30

UPS COMPONENTS • CONVERTER - AC TO DC Ø SPD - PROTECTS AGAINST SPIKES AND TRANSIENTS • BATTERY Ø STORED ENERGY DEVICE - PROTECTS AGAINST INTERRUPTIONS • INVERTER – DC TO AC Ø WAVEFORM SYNTHESIS – PROTECTS AGAINST DC OFFSET AND INTERHARMONICS Ø FILTER – PROTECTS AGAINST HARMONICS, NOTCHING AND NOISE Ø VOLTAGE REGULATOR – PROTECTS AGAINST SAGS, SURGES AND FLUCTUATIONS • MONITOR AND CONTROL HARDWARE / SOFTWARE 31

SWITCHOVER TIME • A TYPICAL SWITCHOVER TIME 2 – 4 ms ONE QUARTER CYCLE OR LESS FOR SOME EQUIPMENT THIS IS NOT TOLERABLE 32

ADVANTAGES / DIS-ADVANTAGES OF THE DIFFERENT UPS ARCHITECTURES • LINE INTERACTIVE ADVANTAGES Ø AC TO DC CONVERTER / BATTERY CHARGER DOES NOT HAVE TO PROVIDE FULL LOAD POWER (POTENTIALLY CHEAPER) Ø LESS STRESS ON DC TO AC INVERTER SINCE IT RUNS AT NO LOAD UNTIL UPS SWITCHES TO BATTERY POWER (POTENTIALLY CHEAPER) • ON-LINE ADVANTAGES Ø ZERO SWITCHOVER TIME FROM MAIN LINE TO BATTERY POWER Ø ALWAYS ISOLATED FROM POWER DISTURBANCES ON THE MAIN LINE 33

SIZING THE UPS • EQUIPMENT RATINGS FOR LOADS Ø OBTAIN RATINGS FROM NAMEPLATE OR SPEC SHEET Ø ENERGY USAGE MAY BE SPECIFIED IN VOLT AMPS (VA) OR WATTS (W) AND IN VALUES THAT ARE EITHER MAXIMUM OR NOMINAL Ø (VA) AND (W) ARE RELATED VIA THE POWER FACTOR • TOTAL UPS LOAD MUST NOT EXCEED THE UPS VOLT AMP (VA) RATING • TOTAL UPS LOAD MUST NOT EXCEED THE UPS WATT (W) RATING • OVERSIZE / DERATE TO ADD LIFE • RUNTIME CHARTS 34

UPS SIZING – EXAMPLE SPREADSHEET 35

BATTERY SAFETY • MAINTENANCE Ø INSPECT PERIODICALLY Ø REPLACE AS NEEDED • RISKS Ø Ø Ø ACID ELECTRIC SHOCK BURN FLYING, MOLTEN METAL (EYES) INJURIES RESULTING FROM CARRYING HEAVY BATTERY PACKS • DISPOSAL Ø DISPOSE OF PROPERLY Ø RECYCLE WHENEVER POSSIBLE 36

GENERAL DISCUSSION • DOES A UPS OFFER COMPLETE PROTECTION? • DO YOU THINK “POWER DISTURBANCES WON’T HAPPEN TO YOU” ? • MISCELLANEOUS 37

DOES A UPS OFFER COMPLETE PROTECTION? • SOME POWER DISTURBANCES MAY EXCEED THE HANDLING CAPABILITY OF THE UPS • UPS FAILURE 38

DO YOU THINK “POWER DISTURBANCES WON’T HAPPEN TO YOU” ? • POWER DISTURBANCES OCCUR FREQUENTLY, THOUGH MANY ARE SMALL AND WITHOUT CONSEQUENCE • AN ON-LINE UPS CAN PROTECT AGAINST MORE SIGNIFICANT POWER DISTURBANCES WHEN THEY DO OCCUR • THE COST OF NOT HAVING A UPS CAN EASILY EXCEED THE COST OF A UPS 39

MISCELLANEOUS • MANY RETAIL UPS FOR COMPUTER APPLICATIONS ARE LINE INTERACTIVE • MANUFACTURERS AND BUILDING CODES DO NOT ALLOW EXTENSION CORDS OR SURGE SUPPRESSORS TO BE USED WITH A UPS 40

SUMMARY THINGS TO CONSIDER WHEN SPECIFYING A UPS • POWER QUALITY Ø ARCHITECTURE - LINE INTERACTIVE OR ON-LINE Ø WAVEFORM - SQUARE, MODIFIED SINE, TRUE SINE Ø IMMUNITY TO DISTURBANCES OTHER THAN OUTAGE • • RUN TIME WITH AN OUTAGE RELIABILITY AUDIBLE NOISE MONITOR AND CONTROL HARDWARE / SOFTWARE Ø LOCAL / REMOTE CONTROL • INITIAL COST • MAINTENANCE COST • WARRANTY 41

REFERENCES • IEEE STANDARD 1100 -2005 RECOMMENDED PRACTICE FOR POWERING AND GROUNDING SENSITIVE ELECTRONIC EQUIPMENT • IEEE STANDARD 1159 -1995 RECOMMENDED PRACTICE FOR MONITORING ELECTRICAL POWER QUALITY 42

QUESTIONS 43