1 RESOLVING TRANSFORMER NOISE AND ELECTRICAL HARMONICS PROBLEMS ASSOCIATED WITH DEEP WELL PUMPING SYSTEMS Craig Patterson, Project Engineer, Meurer & Associates.

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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 GroupDavid Kaunisto, District Manager, East Cherry Creek

Valley Water & Sanitation District

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East Cherry Creek Valley Water & Sanitation District

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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)

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Deep Well Installation Diagram

480 Volts 480 Volts 2300 Volts

SUBMERSIBLE WELL PUMP AND MOTOR

UTILITYTRANSFORMER

(XFMR)

VARIABLE FREQUENCY

DRIVE(VFD)

STEP-UP TRANSFORMER

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Deep Well Installation Diagram

480 Volts 480 Volts 2300 Volts

1-YEAR

10-YEAR

PUMPING WATER LEVEL (PWL)

PUMPING WATER LEVEL (PWL)

VFD

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Variable Speed Pumps

70 Hz

60 Hz

50 Hz

Head

3000

2000

0 Gallons Per Minute

0 200 400 600

10 Year PWL

1 Year PWL

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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%.

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Discussion of Problem – Power Factor The current lags the voltage

because of motor load.

Vol

tage

Cur

rent

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Discussion of Problem – Transformer Noise

Complaints from neighbors about transformer noise.

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Transformers

Step-up

Utility

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Physical Muffling of Transformer Noise by Fence

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Goal

Equipment combination that will:

Provide adequate power factorReduce noise to acceptable levelProvide operating flexibility to meet varying demands.

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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.

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Variable-Frequency Drive

VFDs

AccusineActive Filter

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Variable Frequency Drive

6-step VFD voltage source output

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Electrical Harmonics

Graph of harmonics

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Electrical Harmonics

Graph of harmonics

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Harmonic Current Distortion

Well SL-10 VFD operating without Accusine

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Transformer Vibration

Core

Base connected to box

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How Noisy Is It?

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

Decibels vs. Audible Noise

Au

dib

le

Nois

e

Decibels (dB)

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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.

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Transformer Vibration

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Harmonic Current Distortion

Well SL-10 VFD operating without Accusine

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Harmonic Current Distortion

Well SL-10 VFD operating with Accusine

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Accusine Installation Diagram

480 Volts 480 Volts 2300 Volts

SUBMERSIBLE WELL PUMP AND MOTOR

UTILITYTRANSFORMER

(XFMR)

6-STEPVFD

STEP-UP TRANSFORMER

ACCUSINEACTIVEFILTER

480 Volts

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MTE Load Filter Installation Diagram

480 Volts 480 Volts 2300 Volts

SUBMERSIBLE WELL PUMP AND MOTOR

UTILITYTRANSFORMER

(XFMR)

PWM(VFD)

STEP-UP TRANSFORMER

MTE LOAD

FILTER

480 Volts

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Equipment Tests – P.S. SA-8/SL-8

6-Pulse VFDUtility Transformer 72 dBStep-up Transformer 68 dB

SWE “Quiet” Step-up Transformer 60 dB

12-Pulse VFD with Phase-Shift Transformer

Utility Transformer 68 dBSWE “Quiet” Step-up Transformer 60 dB

TAPS Phasor Step-up Transformer 63 dB

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Equipment Tests – P.S. SA-8/SL-8

Before: Utility Transformer 72 dB

After adding Accusine Active Filter and Quiet Xfmrs:

Step-up Transformer 68 dB

Utility Power Factor 84%

Utility Transformer 66 dB

SWE Quiet Step-up Transformer 60 dB

Utility Power Factor 97%

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Equipment Tests – P.S. A-19/L-19

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%

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

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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 dBSL-1 Step-up Transformer 50 dBUtility Transformer 66 dB, Power Factor 25%

With Accusine operating:SA-1 Step-up Transformer 55 dBSL-1 Step-up Transformer <50 dBUtility Transformer 59 dB, Power Factor 95%

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$ 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 $13,000260 KVA $11,300 260 KVA $17,600

PCS300 Accusine Active Filter $36,900 MTE Load Filter $4,500 Transportation and Installation – Add 20 - 30%

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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.

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Questions?

Craig Patterson, Project Engineer, Meurer & AssociatesPaul D. Goldfain, Associate Principal, Meurer & Associates

Robert Anderson, Electrical Engineer, The RMH GroupDavid Kaunisto, District Manager, East Cherry Creek

Valley Water & Sanitation District

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PWM Wave

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PWM Output Wave Forms