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