2Fluke Corporation European Headquarters Eindhoven, the Netherlands Corporate Headquartersnear Seattle, WA, USA
3Fluke CorporationFounded in basement of John Fluke’s home in Springdale, Connecticut, USA in 19482,400 employees worldwideOffices in 21 countries around the worldDistributed in more than 100 countriesManufacturing facilities in Everett (USA), the Netherlands, the U.K. and China
5Industry trends Growing concern for personal safety complexity of today’s systems, bring over voltage risksinternational & national regulations (& guidance)Increased attention on power related issuesderegulation of power distributionIncreasing loads on power systemsShift from reactive maintenance to preventive maintenanceMore work by fewer peopleDecreasing maintenance budgetMore complex equipment
6History of Maintenance Practices 20 years ago…The primary goal of maintenance was loss prevention and the fundamental requirement was to provide the basic need at minimum cost.Today…Companies are researching all possible means to extend the productive lifeTool use by application*ScheduledThermal ImagingUltrasonic testingVibration AnalyzersRecorders/LoggersMotor/Circuit TestOil TestersPredictiveTRENDPQ AnalyzersIR TemperatureInsulation testersPreventiveNetwork TestScope MetersLoop Cal.Clamp MeterDMMSimple TestersReactive
7Types of Maintenance Break-down Reactive Cost Maintenance TimeCostReactiveMaintenanceRepair it when it failsPreventiveMaintenanceMaintenance at regular intervalsTimeCostTimeCostPredictiveMaintenanceProblem detected before predicted failure.Maintenance planned ahead
8Power Quality Effects of bad power quality are not immediately obvious Bad power quality can come from anywhereConsequences could be severe (production loss)Power quality problems are a root cause:MalfunctionShutdownExcessive energy costDecreased lifetime of equipment
10ExampleThis manufacturer is the third biggest power consumer of the local energy supplier. They produce fiber materials for sports equipment.A new heating system was installed on a key processDuring a routine check with a thermographic camera it was discovered there had been an increase in temperature of the neutral conductor.Check with a current clamp revealed 20A Phase currents & 40A Neutral current
11Example A power quality logger was used to gather the needed data. Connection was only possible on the distribution board connection, fused with 250A, not at the heater due to safety reasons.This makes analysis a bit more complex since the heater represents a small part of the total load
12Results Current trend Neutral current Question: Why does the neutral carry 60A and not only 6A which would be the difference between currents in L1, L2 and L3?
13Results 2Conclusion; there is a third harmonic present in the neutral
14Conclusion Further analysis showed that: The reason for the neutral conductor overload clearly is the heating installation, which generates high triplen harmonicsMore unbalances present so further more measurements would be very helpful.What was the cause?Regulators built into the heating system require harmonic filters which were not installed10A fund35A 3rd
15Conclusion Thermal survey gives early warning of a problem Addition of new equipment can introduce problems which are not obvious or visiblePerforming system check “before” and “after” can prevent future failures“Balanced” loads still can have harmonic content running in the neutral
17Measurement Safety Power Quality Measurement The effect of distortion on simple test toolsMeasurement of HarmonicsMeasurement SpecificationsTypical measurementsPower Quality Measurement EquipmentBasic MeasurementsTest equipment types
18Measurement Safety Power Quality Measurement The effect of distortion on simple test toolsMeasurement of HarmonicsMeasurement SpecificationsTypical measurementsPower Quality Measurement EquipmentBasic MeasurementsTest equipment types
19Safety of MeasurementExampleDMM fitted with low energy fuse used incorrectly on a high energy circuit
20EN61010 LV Directive Implemented in 1998 All instruments have to be tested by an independent test house (2004)Each instrument must be marked with an Overvoltage Category ( CAT I, II, III, IV )As well as a voltage level (300, 600, 1000 Volts)3577
21Category Rating CAT IV - Electricity meters and primary connection CAT III - Permanent connection to the fixed installation.CAT II - Appliances, portable tools etc.CAT I - Protected electronic circuits.17111139
22Voltage Rating per Category Test Impulse Rating 3799
23IEC 1010 / EN61010 Regulations are not an option Second edition EN61010 ( 2004 ) requires independent testingRemember Test leads are CAT rated ...
24Available from Fluke Free Safety DVD Not sales focused Information on EN61010Interview with an arc blast survivor
25Measurement Seminar Safety Power Quality Measurement The effect of distortion on simple test toolsMeasurement of HarmonicsMeasurement SpecificationsTypical measurementsPower Quality Measurement EquipmentBasic MeasurementsTest equipment types
26Harmonics Distorted waveforms Harmonic frequencies combine with the fundamental sinewave to form non-sinusoidal (distorted) waveforms.=
2859.2 A AC 40.5 A AC Measurement Methods Both Clamp Meter’s are calibrated and functioning correctly59.2 A AC40.5 A AC
29Measurement SinewaveHow does a measurement device measure the effective value of a waveform ?Two Methods - Averaging & True RMS
30Averaging Measurement Effective (RMS) value = 1.11 X Average value.
31Non-linear Loads Switching Power Supply VoltsAmpsWhat happens to the measurement device if the waveform is distorted by non-linear loads ?
32Measurement Distorted Waveform Effective (RMS) value = 1.85 x Average value.An averaging measurement device (1.11 x) would read up to 40 % too low.RMSAVG
33Averaging Measurement Nuisance tripping at 60A ?True RMS MeasurementAveraging Measurement59.2 A AC40.5 A AC
34True RMS Measurement True RMS / Harmonics A True RMS meter calculates the effective heating value of the distorted waveformThis will include all harmonics.
35Crest FactorPeak value = X RMS value.1.414 = Crest Factor.
36Crest Factor Distorted Waveform Peak value = 2.9 X RMS Value.2.9 = Crest Factor.PeakRMS
37Crest Factor Distorted Waveforms C.F. = 1.43C.F. = 2.39C.F. = 4.68Professional Multimeters usually rated at CF <3High Quality units rated at CF of 6Power Quality Analyzer CF >11.
38Power Measurement Two Power Factors Screen Shots from a Fluke 43 Single Phase and a Fluke 434 Three Phase analyser
39Power Measurement System with no Harmonic content True Power (W)Reactive power (kVAr)Cos φ (dpf) = true power (fundamental)Apparent power (kVA)
40Power Measurement System with Harmonic content Reactive power (kVAr) True Power (W)Reactive power (kVAr)Reactive power(Harmonic component)Cos φ (dpf) : true power/Reactive power (fundamental)PF: true power/reactive power (incl harmonics)Apparent power including harmonics (kVA)
41Power Measurement Two Power Factors ! Screen Shots from a Fluke 43 Single Phase and a Fluke 434 Three Phase analyser
42Measurement where Harmonics are present Always use True RMSCheck the crest factor ratingWhen measuring power be aware of PF vs Cos φ/(DPF)C.F. = 1.43C.F. = 2.39C.F. = 4.68
44VIRTUALLY ALL HARMONIC PROBLEMS ARE GENERATED “IN HOUSE” EN50160 HarmonicsUpper limits for individual harmonic voltages at the supply terminals in % of nominal voltage. 95% of 10-minute average Vrms over 1 week must be below limitsOdd harmonicsEven HarmonicsNot multiples of 3Multiples of 3Order hRelative voltage56 %35 %22 %791.5 %41 %113.5 %150.5 %6…24133 %2117192325VIRTUALLY ALL HARMONIC PROBLEMS ARE GENERATED “IN HOUSE”
45IEC 61000-4-30 specification Test Equipment Class AClass BMeasurementIntervalAccuracyPower frequencyHz10 sec± 10mHzManufacturer to indicateMagnitude supply voltageVrms10 cycles± 0.1%Flicker (IEC )Plt2 hr± 5%Voltage dips, swells and interruptions, rapid voltage changes½ cycle Vrms10 ms± 0.2%Unbalance (method of symmetrical components)Vrms fundamental± 0.15% (uncert.)Harmonics (IEC )THD, Harm V, A, Inter harmonics± 1-5%Transients (not specified)V peak50 μ sec (200KS/s)Mains signalingInter harmonicFlaggingDip, swells, interruptions might create unreliable readings of Hz, Vrms, Unbalance and Harm. Therefore Must be re flagged (dirty) to avoid miss interpretationNot specifiedTime synchronizationExternal clock; GPS1 period
46Harmonic Measurement For troubleshooting Check the harmonics present Check for the levels of the harmonicsLook for recognizable patterns50 Hz100 Hz150 Hz200 Hz
47Harmonic Measurement – PC Load V, A, Hz MeasurementHarmonic Measurement3rd Harmonic Content
49Measurement Seminar Safety Power Quality Measurement The effect of distortion on simple test toolsMeasurement of HarmonicsMeasurement SpecificationsTypical measurementsPower Quality Measurement EquipmentBasic MeasurementsTest equipment types
50Types of Measurement Tools Power Quality Troubleshooting / Survey toolsDevices designed as a measurement toolSimple to use / Immediate measurementsTroubleshooting / Survey tool / some loggingPower Quality “Logging”Devices designed for long term monitoringRecord every parameter for detailed analysisPredictive Maintenance
521) Volts, Amps & Frequency Using a Power Quality AnalyserView all of the main parameters at point of connectionGraphical as well as numeric display can help highlight potential problemsScopeVectorTrend
532) Power Measurement Typical power measurement information Shows the sides of the triangle
554) Transient Measurement Cause….. interferenceDifficult to captureTriggering of ‘scopes difficult…width, timing, peak value ?Modern power quality analyzers purpose built for the jobEnvelope triggerAccurate real time stamping is essential+X%240V- X%
565) Dips and SwellsRecording of upstream and downstream sags can indicate loads causing problemsUpstream SagDownstream Sag
576) UnbalanceThe phase diagram gives a quick indication of phase relationships and balanceIn this example voltage unbalance is very small, but current unbalance is nearly 19%.
587) Flicker Measurements A reading greater than 1 means that most people will perceive flicker in an incandescent bulbMeasurementPst (1 min): Short-term flicker over 1 minutePst: Short-term flicker over 10 minutesPlt: Long-term flicker over 2 hours
59Three Phase Inrush Measurement Inrush Current MeasurementMomentary peak of current during switch on.Current clamps can capture peak readingAnalyzers can give time measurementScreen Shot of a PQA showing start-up current generated by a cooling systemThree Phase Inrush Measurement
609) TemperatureMany power quality problems initially result in an increase in temperature of components, connectors, cables and machineryInfra red non contact measurement is the ideal way to locate this type of problem
61Why infrared non-contact measurement? 1) Measurement from distanceDangerous to contact (Electrical)Difficult to reachMoving objects2) Measurement without contactVery hot objectsWhere contact would damage, contaminate or change temperature (Food & Chemical)
63SubstationsBoth qualitative and quantitative inspections are Required to determine a fault
64Electrical connections The connections on this evaporator pumpread over 50 degrees hotter on phase 3
65Electrical connections The temperature readouts show that connection on the centre phase of this main lighting disconnect are hot, suggesting an unbalanced load
66Electrical connections A PVC cable should not exceed 70 C in Europe, meaning 40 C for max ambient temperature and 30 C for overheating above ambient.Note. In the USA made application notes the value mention for overheating is 40 C, not 30 C