2006 0906 uninterruptible_power_supplies
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UNINTERRUPTIBLE POWER SUPPLIES
JOHN LIGUORI
CONSULTING ENGINEER
MSEE, PE
PRESENTED TO THE IEEE LONG ISLAND CONSULTANT’S NETWORK
9/6/06
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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.
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UNINTERRUPTIBLE POWER SUPPLIESOUTLINE
• INTRODUCTION• POWER DISTURBANCES• UNINTERRUPTIBLE POWER SUPPLIES• GENERAL DISCUSSION• SUMMARY• REFERENCES• QUESTIONS
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INTRODUCTION
• PURPOSE• WHAT IS AN UNINTERRUPTIBLE POWER SUPPLY?• WHY USE A UPS?
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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.
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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
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WHY USE A UPS?
• PROTECTS AGAINST MULTIPLE TYPES OF POWER DISTURBANCES
• ONLY DEVICE THAT PROTECTS AGAINST AN OUTAGE• OFFERS PROTECTION AGAINST
EQUIPMENT NOT OPERATING PROPERLYCOMPUTER AND EQUIPMENT DAMAGEDATA LOSSTIME AND EXPENSE TO RECOVER BACK TO WHERE
YOU WERE, IF EVEN POSSIBLE
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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
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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
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TYPES OF POWER DISTURBANCES
• INTERRUPTION• SAG, UNDER VOLTAGE• SURGE, OVER VOLTAGE• VOLTAGE FLUCTUATION• FREQUENCY VARIATION• SPIKES / TRANSIENTS
IMPULSIVE OSCILLATORY
• WAVEFORM DISTORTION DC OFFSET HARMONICS INTERHARMONICS NOTCHING NOISE
• VOLTAGE IMBALANCE
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DURATION OF POWER DISTURBANCES
• INSTANTANEOUS - ½ CYCLE (8 1/3 ms) OR LESS• MOMENTARY - ½ CYCLE TO 3 SEC• TEMPORARY - 3 SEC TO 1 MIN• SUSTAINED - GREATER THAN 1 MINUTE
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CLASSIFICATION OF PROBLEMS RESULTING FROMPOWER DISTURBANCES
• DISRUPTIVE EQUIPMENT DOES NOT OPERATE AS INTENDED
• DISSIPATIVE EQUIPMENT EXPERIENCES REPEATED STRESSES THAT LEAD TO
FAILURE LATER FOR NO APPARENT REASON
• DESTRUCTIVE EQUIPMENT FAILS AT THE INSTANT THE DISTURBANCE OCCURS
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PROBLEMS RESULTING FROMPOWER DISTURBANCES
• DATA ERRORS• DATA LOSS• BLOWN FUSES• TRIPPED BREAKERS• INTERFERENCE WITH CONTROL OF LOADS• OVERLOADED NEUTRAL CONDUCTORS• MOTORS
HEATING SPEED VARIATION STALLING AUDIBLE NOISE VIBRATION
• TRANSFORMERS HEATING AUDIBLE NOISE VIBRATION
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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
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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
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WHAT THE OEM CAN DO TO MINIMIZE THE EFFECT OF POWER DISTURBANCES
BUILD EQUIPMENT CONTAINING ONE OR MORE INTERNAL PROTECTIVE DEVICES
SURGE PROTECTIVE DEVICES LINE FILTERS ISOLATION TRANSFORMER BATTERY OR CAPACITOR BACK UP TO INCREASE RIDE THROUGH TIME
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WHAT YOU CAN DO TO MINIMIZE THE EFFECT OF POWER DISTURBANCES
• BUY EQUIPMENT THAT HAS INTERNAL PROTECTIVE DEVICES FOR EXAMPLE, BATTERY BACK UP FOR ANY APPLIANCE THAT
CONTAINS A CLOCK
• USE ONE OR MORE EXTERNAL PROTECTIVE DEVICES SURGE PROTECTORS LINE FILTERS ISOLATION TRANSFORMER VOLTAGE REGULATING LINE CONDITIONER UPS
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PROTECTIVE DEVICES OTHER THAN UPS
• SURGE PROTECTIVE DEVICES – SPD’SPROTECTS AGAINST SPIKES OF LIMITED ENERGY
METAL OXIDE VARISTORS – MOV DIODES GAS TUBES LCR FILTERS HYBRIDS
• LINE FILTERSFILTERS OUT HARMONICS, TRANSIENTS AND NOISE
• ISOLATION TRANSFORMERELIMINATES DC OFFSET AND NOISE
• VOLTAGE REGULATING LINE CONDITIONERAUTOMATICALLY ADJUSTS FOR UNDER AND OVER VOLTAGES
CONSTANT VOLTAGE TRANSFORMER - CVT MOTORIZED VARIAC
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POWER DISTURBANCESAND
PROTECTIVE DEVICES
SURGE PROTECTOR
LINE FILTER ISOLATION TRANSFORMER
VOLTAGE REGULATING
LINE CONDITIONER
ON-LINE UPS
INTERRUPTION YESSAG, UNDER VOLTAGE YES YES
SURGE, OVER VOLTAGE YES YESVOLTAGE FLUCTUATION YES YESFREQUENCY VARIATION YES
IMPULSIVE YES YES YESOSCILLATORY YES YES YES
DC OFFSET YES YESHARMONICS YES YES
INTERHARMONICS YESNOTCHING YES YES
NOISE YES YES YESVOLTAGE IMBALANCE YES
PROTECTIVE DEVICE OFFER PROTECTION?
WAVEFORM DISTORTION
SPIKES / TRANSIENTS
POWER DISTURBANCE
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UPS
• ARCHITECTURES• WAVEFORMS• INVERTER TECHNOLOGY• COMPONENTS• SWITCHOVER TIME• ADVANTAGES / DIS-ADVANTAGES• SIZING• BATTERY SAFETY
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UPS ARCHITECTURES
• LINE INTERACTIVE• ON-LINE
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BLOCK DIAGRAMLINE INTERACTIVE UPS
BATTERY CHARGER
AC SUPPLY
INVERTERDC TO AC
CRITICALLOAD
(AC)
BATTERY
AUTOMATIC SWITCH
AC FAIL
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BLOCK DIAGRAMON-LINE UPS
CONVERTER AC TO DC
AC SUPPLY
INVERTERDC TO AC
CRITICALLOAD
(AC)
BATTERY
AUTOMATIC SWITCH
INVERTER FAIL
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BLOCK DIAGRAMLAPTOP COMPUTER POWER SUPPLY
CONVERTER AC TO DC
AC SUPPLY
CONVERTERDC TO DC
BATTERY
CRITICALLOAD
(DC)
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UPS WAVEFORMS
• TRUE SINEWAVE• MODIFIED SINEWAVE• SQUARE WAVE
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UPS WAVEFORMS
-170
0
170
0 4 8 12 16 20
TIME (ms)
VO
LT
AG
E
TRUE SINEWAVEMODIFIED SINEWAVESQUARE WAVE
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INVERTER TECHNOLOGY FOR TRUE SINEWAVE
• PULSE WIDTH MODULATION - PWM• LINEAR AMPLIFIER• RESONANT INVERTER
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BLOCK DIAGRAMPWM INVERTER
HIGH FREQUENCY GENERATOR
PULSE WIDTH MODULATOR
BASE / GATE DRIVE
TRANSISTOR BRIDGE
TRANSFORMER FILTER
CRITICALLOAD
(AC)
REFERENCE SINEWAVE
GENERATORCOMPARISON
AMPLIFIER
DC POWER
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BLOCK DIAGRAMLINEAR AMPLIFER INVERTER
OSCILLATORAMPLIFIER
SINEWAVE OSCILLATOR
TRANSFORMER
COMPARISONAMPLIFIER
POWERAMPLIFIER
CRITICALLOAD
(AC)
DC POWER
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BLOCK DIAGRAMRESONANT INVERTER
SQUARE WAVE
GENERATOR
SWITCH DRIVE
TRANSISTOR SWITCHES
TRANSFORMERLC RESONANT TANK FILTER
CRITICALLOAD
(AC)
DC POWER
(OR FERRORESONANT)
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UPS COMPONENTS
• CONVERTER - AC TO DC SPD - PROTECTS AGAINST SPIKES AND TRANSIENTS
• BATTERY STORED ENERGY DEVICE - PROTECTS AGAINST INTERRUPTIONS
• INVERTER – DC TO AC WAVEFORM SYNTHESIS – PROTECTS AGAINST DC OFFSET AND
INTERHARMONICS FILTER – PROTECTS AGAINST HARMONICS, NOTCHING AND NOISE VOLTAGE REGULATOR – PROTECTS AGAINST SAGS, SURGES AND
FLUCTUATIONS
• MONITOR AND CONTROL HARDWARE / SOFTWARE
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SWITCHOVER TIME
• A TYPICAL SWITCHOVER TIME 2 – 4 ms
ONE QUARTER CYCLE OR LESS
FOR SOME EQUIPMENT THIS IS NOT TOLERABLE
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ADVANTAGES / DIS-ADVANTAGES OF THE DIFFERENT UPS ARCHITECTURES
• LINE INTERACTIVE ADVANTAGES AC TO DC CONVERTER / BATTERY CHARGER DOES NOT HAVE TO
PROVIDE FULL LOAD POWER (POTENTIALLY CHEAPER) LESS STRESS ON DC TO AC INVERTER SINCE IT RUNS AT NO LOAD UNTIL
UPS SWITCHES TO BATTERY POWER (POTENTIALLY CHEAPER)
• ON-LINE ADVANTAGES ZERO SWITCHOVER TIME FROM MAIN LINE TO BATTERY POWER ALWAYS ISOLATED FROM POWER DISTURBANCES ON THE MAIN LINE
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SIZING THE UPS
• EQUIPMENT RATINGS FOR LOADS OBTAIN RATINGS FROM NAMEPLATE OR SPEC SHEET ENERGY USAGE MAY BE SPECIFIED IN VOLT AMPS (VA) OR WATTS (W)
AND IN VALUES THAT ARE EITHER MAXIMUM OR NOMINAL (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
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UPS SIZING – EXAMPLE SPREADSHEET
ITEM EQUIPMENT DESCRIPTION MANUFACTURER MODEL VOLT AMPSMAX
(va)
POWER
MAX
(w)
NOTES
1 PC2 MONITOR3 EXTERNAL HARD DRIVE 14 EXTERNAL HARD DRIVE 25 AUDIO SYSTEM6 PRINTER 17 PRINTER 28 CABLE MODEM9 LAPTOP / DOCKING STATION
10 PHONE AND ANSWER MACHINE11 LAMP12 CLOCK
TOTAL
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BATTERY SAFETY
• MAINTENANCE INSPECT PERIODICALLY REPLACE AS NEEDED
• RISKS ACID ELECTRIC SHOCK BURN FLYING, MOLTEN METAL (EYES) INJURIES RESULTING FROM CARRYING HEAVY BATTERY PACKS
• DISPOSAL DISPOSE OF PROPERLY RECYCLE WHENEVER POSSIBLE
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GENERAL DISCUSSION
• DOES A UPS OFFER COMPLETE PROTECTION?• DO YOU THINK “POWER DISTURBANCES WON’T HAPPEN TO
YOU” ?• MISCELLANEOUS
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DOES A UPS OFFER COMPLETE PROTECTION?
• SOME POWER DISTURBANCES MAY EXCEED THE HANDLING CAPABILITY OF THE UPS
• UPS FAILURE
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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
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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
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SUMMARYTHINGS TO CONSIDER WHEN SPECIFYING A UPS
• POWER QUALITY ARCHITECTURE - LINE INTERACTIVE OR ON-LINE WAVEFORM - SQUARE, MODIFIED SINE, TRUE SINE IMMUNITY TO DISTURBANCES OTHER THAN OUTAGE
• RUN TIME WITH AN OUTAGE• RELIABILITY• AUDIBLE NOISE• MONITOR AND CONTROL HARDWARE / SOFTWARE
LOCAL / REMOTE CONTROL
• INITIAL COST• MAINTENANCE COST• WARRANTY
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REFERENCES
• IEEE STANDARD 1100-2005RECOMMENDED PRACTICE FOR POWERING AND GROUNDING SENSITIVE
ELECTRONIC EQUIPMENT
• IEEE STANDARD 1159-1995RECOMMENDED PRACTICE FOR MONITORING ELECTRICAL POWER QUALITY
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QUESTIONS