1 Digital Meters - Power Quality Monitoring and Analysis John Levine, P.E. Levine Lectronics and Lectric

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Digital Meters - Power Quality Monitoring and AnalysisJohn Levine, P.E.Levine Lectronics and Lectric

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Contents

• Effects of power quality • Power Quality definitions revisited• What is needed for PQ monitoring ?• Summary

Monitor and Analyze Power Disturbances, Disruptions & Harmonics

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PQ is a Business Problem

Power Quality issues cause business problems such as:

• Lost productivity, idle people and equipment

• Lost orders, good will, customers and profits

• Lost transactions and orders not being processed

• Revenue and accounting problems

• Customer and/or management dissatisfaction

• Overtime required to make up for lost work time

According to Electric Light and Power Magazine, 30 to 40 Percent of All Business Downtime Is Related to Power Quality Problems.

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Is Power Quality Such a Big Problem?

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Why PQ is such a Big Problem?• The sensitivity of today’s electronic equipment

makes it susceptible to power disturbances • For some devices, a momentary disturbance can

cause o scrambled datao interrupted communicationso a frozen mouse o system crashes and equipment failure

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PQ Problems are Expensive

• Berkeley Lab Study Estimates $80 Billion Annual Cost of Power Interruptions … Research News, Berkeley Lab, February 2, 2005

• $50 billon per year in the USA is lost as a results of power quality breakdowns …. Bank of America Report

• A manufacturing company lost more than $3 million one day last summer in Silicon Valley when the “lights went out.” … New York Times January 2000

• “A voltage sag in a paper mill can waste a whole day of production - $250,000 loss” … Business Week, June 17,, 1996

• Half of all computer problems and one-third of all data loss can be traced back to the power line … Contingency Planning Research, LAN Times

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Who is Affected?

• Lost production• Scrap• Costs to restart• Labor costs• Equipment damage and repair• Other costs

• High Cost Facilitieso Semiconductor plantso Pharmaceuticalso Data centers

• Medium Cost FacilitiesoAutomotive

manufacturingoGlass plantsoPlastics & ChemicalsoTextiles

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PQ Definitions RevisitedIEEE CategoriesStd 1159-1995

Short Duration Variations

Typical Duration

Instantaneous Sag 0.5 – 30 cycles

Momentary Sag 30 cycles – 3 sec

Temporary Sag 3 sec – 1 min

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Typical Duration


Momentary Sag 30 cycles – 3 sec.

Temporary Sag 3 sec – 1 min.

Instantaneous Swell 0.5 – 30 cycles

Momentary Swell 30 cycles – 3 sec.

Temporary Swell 3 sec – 1 min.

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Typical Duration


Momentary Sag 30 cycles – 3 sec.

Temporary Sag 3 sec – 1 min.

Instantaneous Swell 0.5 – 30 cycles

Momentary Swell 30 cycles – 3 sec.

Temporary Swell 3 sec – 1 min.

Momentary Interruptions

0.5 – 30 cycles

Temporary Interruptions

30 cycles – 3 sec.

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Long Duration Variations

Typical Duration

Sustained interruptions

> 1 min

Under voltages > 1 min

Over voltages > 1 min

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Typical Duration


> 1 min



Voltage imbalance Steady state

Waveform Distortion

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Typical Duration


> 1 min



Voltage imbalance Steady state

Waveform Distortion

DC offset Steady state

Harmonics Steady state

Inter harmonics Steady state

For Electric Utilities Control of Voltage and Prevention of Outages is Power Quality

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Sources of PQ ProblemsUtility Sources

• Lightning

• PF Correction Equipment

• Faults

• Switching

Internal Sources

•Individual Loads –Lighting, Elevators, Coolers, HVAC

•Uninterruptible Power Supplies

•Variable Frequency Drives

•Battery Chargers

•Large Motors During Startup

•Electronic Dimming Systems

•Lighting Ballasts (esp. Electronic)

•Arc Welders, and Other Arc Devices

•Medical Equipment, e.g. MRIs and X-Ray Machines

•Office Equipment and Computers

•Wiring

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PQ Problems and Possible CausesTypical problems Disturbance Type Possible Causes

Overheated neutralIntermittent lock-upsFrequency deviations

Steady-state Shared neutralsImproper or inadequate wiringHigh source impedanceSCR/Rectifiers and notchingHarmonics

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InterruptionGarbled dataRandom increase in harmonics levels

Utility faultsInrush currentsInadequate wiring

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Intermittent lock-upsLights flickerGarbled data

Sags/Swell Source voltage variationsInrush/surge currentsInadequate wiring

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Component failureDielectric breakdownLock-upsGarbled dataWavy CRTs

ImpulsesEMI/RFI

LightningLoad switchingCapacitor switchingStatic dischargeHand-held radiosLoose wiring/arcing

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Component failureDielectric breakdownLock-upsGarbled dataWavy CRTs

ImpulsesEMI/RFI

LightningLoad switchingCapacitor switchingStatic dischargeHand-held radiosLoose wiring/arcing

Overheated transformers and motorsVoltage and current distortionsGarbled dataLock-ups

Harmonics Electronic loadsSCR/rectifier

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Major PQ Problems

Source: EPRI, 1994

Spikes, 7%

Sags, 56%

Outages,

6%

Swells,

31%

Sags (Dips)

Associated with system faults

Switching of heavy loads

Starting of large motors

Swells

System fault conditions

Switching on a large capacitor bank

Switching off a large load

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Cost of Voltage Sags

Textile Industry

Plastics Industry

Glass Industry

Process Industry

Semiconductors

$1k $10k

$100k $1M $10M

Losses per Voltage Sag Event

Source: EPRI “The Economics of Custom Power”, IEEE T&D Show 2003

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Cost of Momentary Outages

Momentary Outages create problems when computers and clocks reset, equipment stalls, and work stops.

Category Minimum MaximumIndustrialSemiconductor Manufacturing $20.0 $60.0Electronics $8.0 $12.0Automobile Manufacturing $5.0 $7.5Pharmaceutical $5.0 $50.0Glass $4.0 $6.0Rubber and Plastics $3.0 $4.5Petrochemical $3.0 $5.0Food Processing $3.0 $5.0Textile $2.0 $4.0Metal Fabrication $2.0 $4.0Mining $2.0 $4.0Paper $1.5 $2.5Printing(Newspapers) $1.0 $2.0

CommercialHospitals, banks, civil service $2.0 $3.0Communications, information processing $1.0 $10.0Resturants, bars, hotels $0.5 $1.0

Commercial shops $0.1 $0.5Source: EPRI “The Economics of Custom Power”, IEEE T&D 2003

Cost of Momentary Interuption($/kW Demand)

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High Speed Waveform Capture

High Speed Waveform Capture Is the Most Important PQ Troubleshooting Tool

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Benefits of Continuous PQ Monitoring

Continuous PQ Monitoring Detects, Records, and Leads to the Prevention of PQ Problems

• Power Quality monitoring provides a continuous “Health Check” of a facility’s power system … for example:

o Harmonic interaction between loads and power conditioning equipment spotted

o High Inrush currents from equipment startup detected

o Transients from load switching are seen

• It provides data to see, diagnose and avert looming problems – “like squeaky brakes on a car”

o Trends can be detected

o JIT equipment maintenance programs can be established

• It acts like a “Black Box” on an airplane to tell you what, when, and where a Power Quality event occurred … to prevent it from reoccurring

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What is needed for PQ Monitoring?PQ Monitors must detect and record the 7 types of PQ problems

•Transients•Interruptions•Sag/Under Voltage•Swell/Over Voltage•Waveform Distortion•Voltage Fluctuations•Frequency Variations

These include Flicker and Compliance to ITI(CBEMA), IEEE and ISO Standards

Plus they must …

• Be easy to use• Be Suitable for continuously

monitoring indoors and outdoors

• Interface with standard PQ analysis Software…PQDif format

• Be fast enough to capture high speed events that produce equipment problems

• Have enough storage to save the waveforms you need

• Have PQ analysis tools that produce usable, actionable recommendations

ITI: Information Technology Industry Council (Computer & Business Equipment Manufacturer’s Association)

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Real Time Field Recorded Events

Source: AGA Brazil

Meter: EPM9650

Period: Jan 2005 – Dec 2005

Continuous Monitoring of the Station for PQ Problems

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PQ Meter ITI Capture

Equipment Interrupting Voltage Sags as Recorded

Damage Inducing Voltage Surges as Recorded

ITI Acceptable Power Disturbance Envelope

ITI: Information Technology Industry Council (Computer & Business Equipment Manufacturer’s Association)

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Instantaneous Sag Event

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Instantaneous Swell Event

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Harmonic & Interharmonic Spectrum

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Flicker Recording

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Flicker Recording

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Summary

GE Multilin provides the necessary tools for a successful PQ disturbance analysis and allows users to take remedial actions

Accurate Measurement to determine actual

state

Examinations

Remedial actionsRemedy

Feels the pulse of the power system network

Symptoms

High resolution recordings for longer

durationsGE Communicator

software

Diagnosis

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Finally…

If You Can’t Measure it You Can’t Manage it

If You Can Measure it You Can Manage it

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Proper Phasors

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Proper Phasors

Documents

1 Digital Meters - Power Quality Monitoring and Analysis John Levine, P.E. Levine Lectronics and Lectric