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UST Power Quality Basics

Jun 22, 2015



The cost of electrical events – surges, sags and brownouts – to industry. Power quality terms defined. Power conditioner/voltage regulation solutions compared.

  • 1. Utility Systems Technologies, Inc. Quality Power. Better Business.Power Quality Basics 2009, Utility Systems Technologies, Inc All rights reservedSpecifications subject to change without noticeSure-Volt, Sag Fighter and Mini- EVR are trademarks of UST power conditioners

2. Power QualityWho cares? $100+ billion in losses per year Just in the U.S. Financial impact Scrap, equipment damage, etc. Operational impact Downtime, critical shipments, etc.Power Quality = Financial Problem 3. Power QualityTrends Electric grid degradation Sensitive loads Energy costs Environmental regulations Financial sensitivityA Perfect Storm 4. Power QualityWhat does Quality mean? Absence of malfunctions or failures Depends on point of view Utility has one view Customer may have another viewQuality = Proper Equipment Operation & Longevity 5. Power QualityPower = Current, Time & Voltage Amps are governed by the load Time cannot be changed Only voltage is controllablePower Quality = Voltage Quality 6. UndervoltageVoltage 90% of nominal or lessSource: Utility or facility Duration: > 1 minute Incidence: Medium - high Symptoms: Malfunction or premature equipment failure Protection: Voltage regulationUndervoltage can result from low distribution voltage, high voltage drop, heavy loads, etc. Symptoms include premature failure and overheating of motors. May also increase sensitivity to voltage sags.Causes Equipment Shut Down or Malfunction 7. OvervoltageVoltage >110% above nominalSource: Utility Duration: > 1 minute Incidence : Medium - high Symptom: Malfunction or premature equipment failure Protection: Voltage regulationOvervoltage usually results from high distribution voltage. Often a problem nights, evening and weekends. Premature failure of electronics and printed circuit boards is a common symptom.Causes Premature Circuit Board Failure 8. Distribution Voltage RegulationBrownout intentional reduction in grid voltage Major Cause of Under/Overvoltage 9. Daily Voltage FluctuationsUtility Has Limited Control of Deviations 10. Voltage SagVery short, deep voltage dropSource: Utility or large load start Duration: 0.5 cycles 60 seconds Incidence : Avg. 40 60 events/year in U.S. Symptom: Shut down or malfunction Protection: Sag protectionVoltage sags are particularly problematic for industry where the malfunction of a device may result in huge financial losses. Weather and utility equipment problems are major cause of sags.Cause Frequent Shut Down of Sensitive Loads 11. Voltage SagsAffect large areas Events usually start on the transmission or distribution system Weather events Cap bank switching Affect huge areas 75% of sags affect 1 phaseOften Seem Like Very Brief Interruptions 12. SwellVery short, high voltage riseSource: Utility or facility Duration: 0.5 cycles 60 seconds Incidence : Very low Symptom: Malfunction Protection: Voltage isolationSwells are not a common problem. Most often caused by energizing a capacitor bank or the sudden shut down of very large loads.Most Often Causes Control Problems 13. InterruptionVoltage 1 hour Incidence : ~2 per year in U.S. Symptom: Equipment shutdown Protection: Energy storage or self-generationEnd users in North America experience real interruptions only a few times per year. Voltage sags occur much more frequently and may be mistaken for interruptions.Causes Little Equipment Damage 14. NoiseDistortion of voltage waveformSource: Power Electronics Duration: Steady state Incidence : Low Symptom: Malfunction Protection: Filters or transformersNoise seldom reaches the level of being a major power quality problem. Removing or correcting the source of the noise or applying an appropriate filter are the most common remedies.Causes Malfunctions or Overheating 15. HarmonicsDeformed voltage waveformSource: Power Electronics Duration: Steady state Incidence : Low - medium Symptom: Overheating or malfunction Protection: FiltersHarmonics seldom reach the level of being a major power quality problem. High levels of harmonics can be treated by modifying or isolating the source or applying active or passive harmonic filters.Causes Significant Overheating 16. TransientVery high voltage pulseSource: Typically lightning Duration: 1 minute101 110%Medium/$$-$$$HarmonicsConstant0 20%Low/$-$$NoiseConstant0 1%Low/$-$$NotchingConstantProblem Transient*Interruption*UnbalanceFluctuatingVery Low/$ 0 15% Phase-PhaseMost Problematic *Medium/$-$$ 21. Identifying PQ ProblemsDocument symptoms & conditionsIdentify potential PQ problem & sourceConfirm PQ problem & sourceProblem Identification Is Key 22. Document SymptomsRecord suspected PQ events Malfunction or damage Time & date Any power info available Weather conditions Operating situation Loads starting/stopping Recent changes Other anomaliesFirst Step in Solving PQ Problems 23. Identify ProblemsA process of elimination Measure RMS voltages over time At service entrance At machine level Check unbalance Then, check for sag or transients Then, check for noise or harmonics Etc.Electrical Forensic Investigation 24. Power Quality MonitoringInvaluable Protection Easily identify problem & trends Permits proactive protection Support for insurance claims Protect major investments Relatively inexpensive ($2 5K) At least one unit at service entranceAn Important Maintenance Tool 25. Confirm SourceCompare records & measurements Records should confirm measurements Identify source of problem External, internal or both Identify PQ problem type May be multiple problemsSolution Depends on Source & Problem 26. Under/Overvoltage Solutions Typical products DevicekVA SizeAdvantagesDisadvantagesServo-mechanical voltage regulator5 2,000Low priceSlow response High MaintenanceElectronic tap switching voltage regulator5 2,000Very fast response Solid stateHigher price0.5 - 25Very fast response Solid stateVery poor efficiency Single phase onlyFerroresonant transformerThree phase regulators are often used to correct voltage unbalanceVoltage Regulators 27. Voltage Sag Solutions Typical products DevicekVA SizeAdvantagesDisadvantagesUPS5 2,000Line isolation Many choicesPoor efficiency High costFlywheel20 150No batteriesSmall sizes Mechanical device10 2,000Lowest cost Very high efficiencySag protection onlyActive voltage conditionerSwells often require a custom solutionVery Different Technology Choices 28. Interruption Solutions Typical products DevicekVA SizeAdvantagesDisadvantagesUPS double conversion5 2,000Voltage regulation Line isolationPoor efficiency High O&M costUPS line interactive20 50Voltage regulation Lower costMostly smaller sizesUPS - standby0.3 5Lowest cost Very high efficiencyNo regulationLots of Products Lots of Confusion 29. Noise & Harmonics Solutions Typical products Filters, transformers and other devices Passive devices designed for a specific problem Active devices respond to changing problems Typically designed for the specific applicationSolutions May Require Customization 30. Transient Solutions Typical products TVSS Transient Voltage Surge Suppressor Large variation in protection levels & price Usually applied at service entrance May be included in other devicesInexpensive Protection from Catastrophe 31. Comparing Typical Solutions Effectiveness for Power Quality Problems Power Conditioner TypeUndervoltage OvervoltageVoltage SagsInterruptionsTypical Efficiency (%)Mechanical Voltage RegulatorFair - GoodNoneNone97 - 99Electronic Voltage RegulatorSuperiorPoor - FairNone95 - 99Ferroresonant TransformerGood - SuperiorPoor - FairNone60 - 90Active Voltage ConditioningNone - PoorSuperiorNone - Poor94 - 99Double Conversion UPS w/o BatteriesFair - GoodNone - PoorNone85 - 94Double Conversion UPS with BatteriesFair - GoodGood - SuperiorGood - Superior85 - 94FairGoodGood94 97Standby UPSNone - PoorPoor - FairGood97 98Flywheel UPSNone - PoorSuperiorPoor - Fair96 98Line Interactive UPSNo Device Solves Every Problem 32. Power ConditionersWhat is a power conditioner? No standard definition Traditionally a voltage regulating device with other capability Could be almost anything Check the specsA Very Confusing Term 33. Evaluating PQ SolutionsWhat is the best solution? Define $ cost of PQ problems Define cost of solution Calculate solution effectiveness Calculate paybackSimple Cost-Benefit Analysis 34. Cost of PQ ProblemsDefine $ cost per PQ event Scrap, disposal & cleanup Lost productivity & overtime Lost energy or extra energy Maintenance & service costs Extra QA or mandatory reportingEasy to Under-Estimate PQ Costs 35. Cost of PQ SolutionsOwning cost of PQ solutions First cost + installation Operation & maintenance Energy cost Service & maintenance labor Regular replacement parts Batteries, capacitors, etc.O&M Can Be a Major Cost 36. PQ Solution EffectivenessHow many events are avoided? Compare performance to problems Will solution correct all events Availability & reliability Is solution on-line 24/7/365 Estimate service or recharge time Adjust effectiveness for unavailabilityConsider Time Off-line Solution Requires 37. Solution PaybackCalculate value of solutions Problem Cost - Solution Cost --------------------$ SavingsSolution First Cost $ Savings --------------------Investment PaybackPayback May Be In Months or # of Events 38. Sag Protection ExampleA food/beverage plant 5 deep voltage sag events/year Shut down only bottling line Rest of plant rides through sags But, bottling line shutdown stops plant Costs $20,000 per sag event Bottling line needs 500 kVAA Typical Problem 39. Sag Protection ExampleCompare UPS and sag mitigator each 500 kVA, 480V, 3 phase UPSSag Mitigator$210K$130K$7KN/AAnnualized wear parts (batteries)*$18KN/AAnnual energy losses**$50K$4KTotal annual operation & maintenance c

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