The Natural Ester Experience

Natural Esters leaks

Clean up is done by ice blasting and it

also draws bugs

DGA Analysis

• It look as if that when the transformer reaches

above 55° C the oil starts to produces ethane

• There is usually higher than expected

Hydrogen

• The water content will be higher than

expected. Water can have up to 200 ppm to

400ppm and still be consider normal

(saturates around 1000 ppm)

DGA continued

• DP number can not be counted on as with

mineral oil the equation is for mineral oil this

has been field verified with forensic

teardowns

• Oxidization stability

DGA Example New Transformer designed

for Natural Ester

240 MVA top rated

GAS Date Date Date Date

09/08/2011 05/19/2011 03/02/2011 12/15/2010

Temp C 56 29 52 3

Hydrogen 51 44 55 <5

Methane <1 2 <1 <1

Ethane 144 124 138 <1

Ethylene <1 <1 1 <1

Acetylene <1 <1 <1 <1

Carbon

Monoxide

64 75 39 25

Carbon Dioxide 613 405 243 42

Oxygen 2192 3458 3425 3318

Nitrogen 97781 88923 86167 21971

Water 19 37 11 62

Retro filled unit

GAS Date Date Date Date

07/21/201 05/20/2010 06/23/2009 11/09/2007

Temp C 33 24 53 32

Hydrogen 5 5 <5 <5

Methane 5 6 2 6

Ethane 400 374 430 270

Ethylene 33 17 19 10

Acetylene <1 <1 <1 <1

Carbon

Monoxide

68 34 46 32

Carbon Dioxide 2171 1911 2220 1212

Oxygen 3671 5865 12794 4388

Nitrogen 78147 77776 121018 7361078

Water 78 66 151 49

Retro filled unit earlier

GAS Date Date- NEF Date - mineral Date - mineral

11/06/2002 11/04/2001 03/27/2001 06/04/199

Temp C 8 32 4 30

Hydrogen <5 <5 5 <5

Methane 3 2 5 11

Ethane 3 12 6 11

Ethylene 2 4 5 15

Acetylene <1 <1 <1 <1

Carbon

Monoxide

<25 61 <25 <25

Carbon Dioxide 1081 792 1076 6637

Oxygen 2044 7267 2192 1383

Nitrogen 88116 82970 99169 82129

Water 33 35 16 12

Testing

• Power factor: expect higher than expected results 2 to 3 times higher than mineral oil results after the natural ester has thermo cycled into the insulation can take up to a year

• Power factor testing in cold will give you false results due the fact that water freezes. Winding resistance to ground is much lower than expected in retro-filled units, and it will take some time for it to show up in new units (M ohms to K ohms)

• SFRA results are similar to mineral oil results but do not compare a retro filled unit to the old mineral oil

Power Factor Results 2006 before

Retro-fill with NEF

Equiv 10kV % Pwr Factor

# Insul. KV mA Watts Meas PF Corr PF

1 CH + CHL 10.01 36.658 1.945

2 CH 10.007 14.461 0.547 0.38 0.37

3 CHL (UST) 10.005 23.184 1.377 0.59 0.58

4 CHL 23.197 1.398 0.6 0.59

5 CL + CHL 2.501 49.449 3.028

6 CL 2.5 26.259 1.655 0.63 0.62

7 CHL (UST) 2.5 23.188 1.377 0.59 0.58

8 CHL 23.19 1.373 0.59 0.58

PF Results after Retro-fill 2010, after

NEF™ has thermo-cycled

Equiv 10kV % Pwr Factor

# Insul. KV mA Watts Meas PF Corr PF

1 CH + CHL 10.11 37.494 3.813 1.02 1

2 CH 10.1 14.58 1.14 0.78 0.76

3 CHL (UST) 10.006 22.902 2.662 1.16 1.14

4 CHL 22.914 2.673 1.17 1.15

5 CL + CHL 2.5 49.023 6.083 1.24 1.22

6 CL 2.501 26.117 3.511 1.34 1.31

7 CHL (UST) 2.5 22.904 2.58 1.13 1.11

8 CHL 22.906 2.573 1.12 1.1

Power Factor Results 2001 before

Retro-fill with NEF

Equiv 10kV % Pwr Factor

# Insul. KV mA Watts Meas PF Corr PF

1 CH + CHL 10.0 64.43 2.026

2 CH 10.0 13.29 0.684 0.49 0.49

3 CHL (UST) 10.0 51.11 1.394 0.27 0.27

4 CHL 51.14 1.378 0.27 0.27

5 CL + CHL 2.0 14.59 0.506

6 CL 2.0 14.23 0.505 0.35 0.35

7 CHL (UST) 2.0 0.358 0.005 0.14 0.14

8 CHL 0.36 0.001 0.03 0.03

PF Results after Retro-fill 2007, after

NEF™ has thermo-cycled

Equiv 10kV % Pwr Factor

# Insul. KV mA Watts Meas PF Corr PF

1 CH + CHL 10.004 79.834 3.567

2 CH 10.002 15.479 0.906 0.59 0.57

3 CHL (UST) 10.002 64.344 2.654 0.41 0.39

4 CHL 64.355 2.661 0.41 0.41

5 CL + CHL 2.0 13.218 1.385 0.96

6 CL 2.0 12.743 1.384 1.09 1.08

7 CHL (UST) 2.0 0.477 0.012 0.25 0.24

8 CHL 0.475 0.001 0.02 0.02

Fire Point/Operational Differences

• Flash point greater than 300 ° C

• Need to be aware of other requirements

pertaining to quantity of oil for fire protection

NFPA still requires fire protection after 10,000

gallons

• The retro-filled transformer will run hotter

versus a newly designed transformer for NEF

unit about 10 ° to 15 ° C

Fire Wall had to be added

Fire wall

Storage and Handling

• Try to minimize mixing mineral oil with NEF

• Retro-filled benefits disappeared at a 7% mixture with mineral oil - fire point

• Keep it in a sealed air tight container and if it is in a white tote don’t leave it the sun, it will start to oxide

• The EPA has not recognized the differences between mineral oil and NEF for containment or spills

NEF in Cold weather

Thanks and Questions?