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Integrated Testing and Field Certification of Revenue Metering Sites For PQsynergy 2011 Ming T. Cheng Director of Asian Operations 10737 Lexington Drive Knoxville, TN USA 37932 Phone:1.865. 218.5837 [email protected] www.powermetrix.com Taking from Bill Howe’s presentation yesterday Smart Grid can…….. • Precise measurement and verification Otherwise, it will be garbage in and Garbage out……. Poor PQ -> Metering Error -> Lost revenue…. Why do we test a site? • Verify accuracy to protect OUR revenue stream. • Verify accuracy to ensure we fairly bill the customer. • Assure site is wired safely and to codes. Integrated Site Test Philosophy Site Analysis Meter Testing CT Testing Site Testing is an Investment. One with a very good return! What are the costs? (The Investment) Testing Equipment Vehicles (Vans, Trucks) Fuel Metermens’ Pay Time Site Testing is an Investment! What is the Return for the Investment? Increased Revenue! $ $ $ 3 Year Study from a US Municipal with 35,000 Transformer Rated Installations Total Problems Found after 10% of Sites Tested: 96 Percentage of Sites found to have a Problem: 96 ÷ 3,500 ≈ 2.7% Annualized Revenue Recovery: $ 2,248,354 Annualized Revenue Recovery per Problem: ≈ $ 23,420 Annualized Revenue Recovery per Test: ≈ $ 642 Wiring Error 8% 6% 12% Wiring Error CT Problem Problems Encountered 12% 14% 12% 8% 8% 6% 6% 14% 8% 12% 12% 14% 22% 14% 14% 22% 12% 8% 6% 8% 22% 14% 22% 22% 12% 8% 6% 6% 38% 6% CT Problem Administrative Wiring Error Error Administrative Administrative Error Faulty Meter CT Problem Wiring Wiring Error Error 38% Error Faulty Meter PT Problem PT Problem Administrative CT Problem 38%CT Problem Error PT Problem Theft ofMeter Service Faulty Faulty Meter Administrative Wiring Error Administrative 38%Error Error Theft of Service PT Problem Faulty Meter CT CT Faulty Problem Meter 38% Theft ofError Service PT Problem Administrative Wiring Error Wiring PT Problem Error CT Problem Theft ofFaulty Service Theft ofMeter Service Theft of Service 38% Administrative PT Problem 14% Error Any guesses??? Most problems result in revenue loss. 22% Faulty Meter 38% Theft of Service PT Problem What are we testing for: • Wiring problems • Transformer Issues CT PT • Meter problems Consider a Typical Metering Installation Wiring problems show up in many ways. Often as PT or CT issues. Bad Wiring on Voltage Circuit • Can reduce available current to meter so it doesn’t have VA to operate properly • Current drawn by meter reduces voltage seen at meter R1 I Vm UTILITY CONNEC TION Vu Rm R2 V m Vu I * ( R1 R 2) METER Bad Wiring on Voltage Circuit • For 50 ft of #14 wire to the meter, normally we would have: Vu = 120V, I = 0.2A, R1+R2 = 0.036Ω => 0.0075V =>0.006% Error • Consider a bad connection with resistance 4.0 Ω, then Vu = 120V, I = 0.2A, R1+R2 = 4.036Ω => 0.843V =>0.7% Error • A significant error V m Vu I * ( R1 R 2) Bad Wiring on Voltage Circuit Wiring errors can drastically reduce metered power. A simple phase reversal reduces measured power by 33%. Faulty Wiring on the Current Circuit • A faulty connection can easily add a few tenths of an Ohm burden • Improper wiring • Missing commons • Multiple Grounds • Almost all wiring errors result in reduced billing. Wiring on the Current Circuit • Even a little extra resistance in a CT circuit can cause large errors • Using too small a gauge wire can result in over burden 50 ft of #14 wire is 0.14Ω this is more burden than is allowable for a 0.1B class CT. 50 ft of #12 wire is 0.09Ω this is almost the total burden allowable for a 0.1B class CT. • Without any bad connections or other problems using too small a wire size can insure you get the worst performance from your CTs. Errors with Instrument Transformers • Many CTs are only rated at B0.1 and B0.2 • • • • • #16 wire is 4.5 mΩ/ft #14 wire is 2.8 mΩ/ft #12 wire is 1.8 mΩ/ft #10 wire is 1.1 mΩ/ft #8 wire is 0.7 mΩ/ft • 50ft of #12 wire is 0.09 Ω. That is 90% of the allowed burden for a B0.1 CT. CT – Accuracy – Burden - Load 0.3B1.8 CT 0.6 Percentage Accuracy 0.5 1.8 0.4 0.3 Ohm s 0.9 Ohm s 0.2 0.2 Ohms 0.1 0.05 Ohms 1 2 5 10 100 Percent Rated Load 400 Saturation Meter Performance under Real World Conditions • The fact that a meter is accurate in the lab does not mean it is accurate in the field Harmonics Rapidly changing loads Power factor variations • Can all affect accuracy Meter Performance under Real World Conditions • Large “errors” can occur in the calculation of VA and VARS when PF≠1 There is no “official” definition in the presence harmonics. Different meters may implement different definitions Variations can be as large as 15-30 percent between two meters each of which is “working properly” Field Testing Philosophy Site Analysis Meter Testing Step 1 Step 2 CT Testing Step 3 Integrated Site Test Philosophy CT Burden Testing Site Analysis Meter Testing PHASE 0.0 Ω 0.1 Ω 0.25 Ω 0.5 Ω 1.0 Ω 2.0 Ω 4.0 Ω A 2.358 2.360 2.353 2.361 2.349 2.358 NA B 2.227 2.181 2.167 2.179 2.156 2.172 NA C 2.556 2.545 2.562 2.533 2.556 2.530 NA Secondary Amps CT Testing CT Testing Integrated Site Test Philosophy CT ERROR PLOT Site Analysis Meter Testing Amplitude AND Phase Angle Error CT Testing CT Testing Instrument Transformers Control Metered Values … What If They Do Not Produce The Expected Outputs Traditionally Only The Meter Is Tested … But the meter measures only what reaches its terminals Errors with Instrument Transformers • CTs installations can be fully verified in the field Questionable! Good We can verify that the ratio is correct and constant as burden changes. Wiring And Junctions Connect The Meter … What If There Are Wiring Errors Or Poor Connections Poor Junctions Will Over-Burden The CTs And Reduce Revenue Integrated Site Test Philosophy Site Analysis Site Analysis Meter Testing True 3 Phase Vector Diagram Power Quantities CT Testing True 3 Phase Voltage and Current Waveforms Integrated Site Test Philosophy Site Analysis Site Analysis True 3 Phase Voltage and Current Harmonic Analysis Meter Testing CT Testing Integrated SiteSite Test Philosophy Analysis Meter Testing Meter Testing Customer Load Test Real - World Conditions Voltage and Current Harmonics CT Testing Current and Phase Angle Balance Load Box Test Ideal Current and Voltage Waveforms ANSI Full Load, Power Factor & Light Load CT – Accuracy – Burden - Load 0.3B1.8 CT 0.6 Percentage Accuracy 0.5 1.8 0.4 Ohm s 0.3 Site Analysis Meter Testing 0.2 0.9 Ohm s 0.2 Ohms 0.1 0.05 Ohms 1 2 5 10 100 Percent Rated Load CT Testing CT Testing 400 Saturation Errors with Instrument Transformers • CTs require a lot of care to insure accurate measurements. Burden – Over burden reduces CT accuracy. Wiring – Faulty or improper wiring reduces accuracy by increasing burden. Shunt – Failure to remove the safety shunt will not keep the CT from operating but it will reduce the readings by 50-80% Errors with Instrument Transformers CT was OK Meter Registration Error Nameplate=100:5 CT Degraded Wiring B, C Shorted No Ground Installed CT Ratio Error Wiring Error Integrated Site Test Philosophy Site Analysis Site Analysis $ Meter Testing Meter Testing CT CT Testing Questions?