POWER QUALITY. The Silent Gremlin in your Electrical system. Prat Nagu, E.I.T. CTC Engineering, Inc. Ann Arbor, MI

Transcription

1 POWER QUALITY The Silent Gremlin in yur Electrical system Prat Nagu, E.I.T. CTC Engineering, Inc. Ann Arbr, MI

2 Why shuld we care? Cmputer Lckuts (20%) Light flickering (22%) Electrnic card failures (18%) Pwer factr crrectin system failures (17%) Failures in high lad switching (16%) Neutral cnductr verheating (12%) Unexpected breaker peratin (11%) Pwer meters inaccurate readings (6%) And f curse excess lsses and dwntime CTC Engineering, Inc. 2/13/2019 2

3 Typical PQ Issues CTC Engineering, Inc. 2/13/2019 3

4 Electrical Lads 1970s - Pwer Electrnics Resistive Heaters Linear Lads Incandescent Lamps Cnstant speed mtrs Electrnic Ballast Nn-Linear Lads Battery Chargers VFDs CTC Engineering, Inc. 2/13/2019 4

5 Wavefrm Distrtin Electrnic Ballast Battery Chargers PLCs SMPS VFDs Arc Furnace Any ac/dc cnvertr CTC Engineering, Inc. 2/13/2019 5

6 Surces f PQ prblems Utility Lightning Pwer Factr Crrectin Faults Switching End User Individual Lads Lighting lads Elevatrs Clers Office equipment and Cmputers Switch Mde Pwer Supply (SMPS) UPS VFD Battery Chargers Large Mtrs during start up Arcing Equipment Welding Steel manufacturing Medical Equipment MRI, X-Ray, etc. Imprper Electrical System Design Wiring CTC Engineering, Inc. 2/13/2019 6

7 Causes and Slutins PQ Prblems Majr Surces Slutins Frequency Interruptins Vltage variatins The Utility The Utility Lad changing Synchrnus lads Fast PF crrectin Vltage flicker Lad change (welding) Fast PF crrectin Vltage dip Mtr and heavy lad start up Mtr Starters VFD Fast PF crrectin Over vltage Over PF cmpensatin Fast PF crrectin Transients Start up r Switching Cntrlled switches Unbalance Unbalanced lads, phase shift Balance the lads Harmnics Nn linear lads Resnance Active passive filters Detuned capacitrs Imprved VFD peratin CTC Engineering, Inc. 2/13/2019 7

8 Harmnics CTC Engineering, Inc. 2/13/2019 8

9 Harmnics Furier Analysis CTC Engineering, Inc. 2/13/2019 9

10 THD r TDD? IHD n = I n I 1 100% THD I = I 2 2 +I 2 3 +I I2 n 100% I 1 TDD I = I 2 2 +I 2 3 +I I2 n 100% I L Similarly THD V and TDD V CTC Engineering, Inc. 2/13/

11 Chicken r the egg? Lads distrt current wavefrms In turn causes vltage distrtin CFL Vltage Distrtin System Impedance Amunt f distrted current VFD Current Distrtin CTC Engineering, Inc. 2/13/

12 If yu cannt measure it, yu cannt manage it CTC Engineering, Inc. 2/13/

13 Case Study Steel Plants G Industry A Industry B Traf Rating 5 MVA 5 MVA Demand 3.5 MVA 4.9 MVA %THDv %THDi Pwer Factr CTC Engineering, Inc. 2/13/

14 Case Study Steel Plants Timestamp Phase A Phase B Phase C %THDv with Industry-A lads OFF 15: : : %THDv with Industry-A lads ON 15: : : : : : : : : : : CTC Engineering, Inc. 2/13/

15 Expected Harmnics in VFDs What rder f harmnics t expect frm yur VFD? H = np ± 1 E.g.: 6 pulse VFD: 5, 7, 11, 13, 17, 19 Generally magnitude decreases as rder increases Expected harmnics: SMPS 3, 5, 7, 9, 11, 13 Flurescent lights 3, 5, 7, 9, 11, 13 Arcing devices 2, 3, 4, 5, 7 Transfrmer energizatin 2, 3, 4 CTC Engineering, Inc. 2/13/

16 Triplen Harmnics Adds up as neutral return current CTC Engineering, Inc. 2/13/

17 Triplen Harmnics Neutral Cnductr CTC Engineering, Inc. 2/13/

18 Ecnmic impact Oversizing f equipment Lsses inefficiencies PF penalties Incnsistent meter reading Cst assciated with dwntime due t Equipment failure Frequent repairs/ maintenance Cst fr adding harmnic filters CTC Engineering, Inc. 2/13/

19 Thank yu! 4343 Cncurse drive Ann Arbr, MI (906) CTC Engineering, Inc. 2/13/