Craig Patterson, Project Engineer, Meurer & Associates

1. RESOLVING TRANSFORMER NOISE AND ELECTRICAL HARMONICS PROBLEMS ASSOCIATED WITH DEEP WELL PUMPING SYSTEMS Craig Patterson, Project Engineer, Meurer & Associates Paul D. Goldfain, Associate Principal, Meurer & Associates Robert Anderson, Electrical Engineer, The RMH Group David Kaunisto, District Manager, East Cherry Creek Valley Water & Sanitation District

2. East Cherry Creek Valley Water & Sanitation District

3. East Cherry Creek Valley Water & Sanitation District • Approximately 50,000 population • 10-15 MGD yearly range • Water Supply • Arapahoe aquifer (1,500’ - 1,800’ deep) • Laramie-Fox Hills aquifer (1,800’ – 2,300’ deep)

4. Deep Well Installation Diagram 480 Volts 480 Volts 2300 Volts UTILITY TRANSFORMER (XFMR) VARIABLE FREQUENCY DRIVE (VFD) STEP-UP TRANSFORMER SUBMERSIBLE WELL PUMP AND MOTOR

5. Deep Well Installation Diagram 480Volts 480Volts 2300Volts VFD 1-YEAR PUMPING WATER LEVEL (PWL) 10-YEAR PUMPING WATER LEVEL (PWL)

6. Variable Speed Pumps Head 3000 2000 0 70 Hz 60 Hz 50 Hz 10 Year PWL 1 Year PWL 0 200 400 600 Gallons Per Minute

7. Discussion of Problem – Power Factor • Power Factor is the percentage difference between apparent and actual power. • The Electric utility requires at least 95%. • P.S. SA-8 was 84%.

8. Discussion of Problem – Power Factor • The current lags the voltage because of motor load. Voltage Current

9. Discussion of Problem – Transformer Noise • Complaints from neighbors about transformer noise.

10. Transformers Utility Step-up

11. Physical Muffling of Transformer Noise by Fence

12. Goal Equipment combination that will: • Provide adequate power factor • Reduce noise to acceptable level • Provide operating flexibility to meet varying demands.

13. Electrical Analysis • RMH Group analyzed the power systems at several pump stations. • They determined that problem was caused by voltage and current harmonics generated in the VFDs.

14. Variable-Frequency Drive Accusine Active Filter VFDs

15. Variable Frequency Drive 6-step VFD voltage source output

16. Electrical Harmonics Graph of harmonics

17. Electrical Harmonics Graph of harmonics

18. Harmonic Current Distortion Well SL-10 VFD operating without Accusine

19. Transformer Vibration Core Base connected to box

20. How Noisy Is It? decibels (dB) Whisper 30 Light Traffic 40-50 Vacuum Cleaner 70 Garbage Disposal 80 Circular Saw 100 Rock Concert 110-130 Threshold of Pain 108-130 Jet Takeoff 140

21. Decibels vs. Audible Noise Audible Noise Decibels (dB)

22. Equipment Tested • 12-step or Pulse-Width Modulated VFD • More frequent pulsing reduces distortion. • Southwest Electric “Quiet” Transformers • Larger core, rubber supports, sound proofing • MTE load filter (for PWM drive) • Converts VFD output to sinusoidal wave • Accusine “Active” filter • Senses current, then gates just the right amount of power through the filter to correct distortion.

23. Transformer Vibration

24. Harmonic Current Distortion Well SL-10 VFD operating without Accusine

25. Harmonic Current Distortion Well SL-10 VFD operating with Accusine

26. Accusine Installation Diagram 480 Volts 480 Volts 480 Volts 2300 Volts UTILITY TRANSFORMER (XFMR) ACCUSINE ACTIVE FILTER 6-STEP VFD STEP-UP TRANSFORMER SUBMERSIBLE WELL PUMP AND MOTOR

27. MTE Load Filter Installation Diagram 480 Volts 480 Volts 2300 Volts 480 Volts UTILITY TRANSFORMER (XFMR) PWM (VFD) MTE LOAD FILTER STEP-UP TRANSFORMER SUBMERSIBLE WELL PUMP AND MOTOR

28. Equipment Tests – P.S. SA-8/SL-8 6-Pulse VFD Utility Transformer 72 dB Step-up Transformer 68 dB SWE “Quiet” Step-up Transformer 60 dB 12-Pulse VFD with Phase-Shift Transformer Utility Transformer 68 dB SWE “Quiet” Step-up Transformer 60 dB TAPS Phasor Step-up Transformer 63 dB

29. Equipment Tests – P.S. SA-8/SL-8 Before: Utility Transformer 72 dB Step-up Transformer 68 dB Utility Power Factor 84% After adding Accusine Active Filter and Quiet Xfmrs: Utility Transformer 66 dB SWE Quiet Step-up Transformer 60 dB Utility Power Factor 97%

30. Equipment Tests – P.S. A-19/L-19 Well A-19 equipped with Toshiba PWM 12-pulse VFD Well L-19 equipped with Toshiba PWM 6-pulse VFD A-19 Step-up Transformer 81 dB L-19 Step-up Transformer 82 dB Utility Transformer 69 dB Installed MTE Output (Load) Filters A-19 Step-up Transformer 64 dB L-19 Step-up Transformer 69 dB Utility Transformer 62 dB, Power Factor 99%

31. Equipment Tests – P.S. SA-1/SL-1 Both wells equipped with Centrilift 6-step VFDs and SWE Quiet transformers. Without Accusine operating: SA-1 Step-up Transformer 57 dB SL-1 Step-up Transformer 50 dB Utility Transformer 66 dB, Power Factor 25% With Accusine operating: SA-1 Step-up Transformer 55 dB SL-1 Step-up Transformer <50 dB Utility Transformer 59 dB, Power Factor 95%

32. $ Equipment Costs $ • 6-pulse drive $18,000 - $22,000 • 12-pulse drive $22,000 – $24,000 • “Regular” Step-Up Xfmr SWE “Quiet” Xfmr 130 KVA $7,600 130 KVA $13,000 260 KVA $11,300 260 KVA $17,600 • PCS300 Accusine Active Filter $36,900 • MTE Load Filter $4,500 • Transportation and Installation – Add 20 - 30%

33. Results • Installation of “Quiet” transformers generally reduced transformer noise by 1/2. • Installation of Accusine “Active Filter” corrected power factor to better than 95%, and reduced utility transformer noise. • Installation of MTE load filter on PWM drives reduced transformer noise by almost 1/2.

34. Questions? Craig Patterson, Project Engineer, Meurer & Associates Paul D. Goldfain, Associate Principal, Meurer & Associates Robert Anderson, Electrical Engineer, The RMH Group David Kaunisto, District Manager, East Cherry Creek Valley Water & Sanitation District

35. PWM Wave

36. PWM Output Wave Forms